SqlParser.Net is a free, comprehensive and high-performance SQL parsing engine library that can help you parse and process SQL simply, quickly and efficiently. SqlParser.Net是一个免费,功能全面且高性能的sql解析引擎类库,它可以帮助你简单快速高效的解析和处理sql。
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Jan 1, 2026
$ dotnet add package SqlParser.Nethi 大家好,我是三合,在过往的岁月中,我曾经想过要写以下这些工具
但是无一例外,都失败了,因为要实现以上这些需求,都需要一个核心的类库,即sql解析引擎,遗憾的是,我没有找到合适的,这是我当初寻找的轨迹
JsonConvert.SerializeObject(statements.First(), Formatting.Indented)
// Elided for readability
{
"Query": {
"Body": {
"Select": {
"Projection": [
{
"Expression": {
"Ident": {
"Value": "a",
"QuoteStyle": null
}
}
}
...
额,怎么说呢,这语法树也太丑了点吧,同时非常难以理解,跟我想象中的完全不一样啊,于是也只能pass。
接下来我又发现了另外一些基于antlr来解析sql的类库,比如SQLParser,因为代码是antlr自动生成的,比较难以进行手动优化,所以还是pass。
最后我还发现了另外一个gsp的sqlparser,但它是收费的,而且巨贵无比,也pass。
找了一圈下来,我发现符合我要求的类库并不存在,所以我上面的那些想法,也一度搁浅了,但每一次的搁浅,都会使我内心的不甘加重一分,终于有一天,我下定决心,自己动手,丰衣足食,所以最近花了大概3个月时间,从头开始写了一个sql解析引擎,包括词法解析器到语法分析器,不依赖任何第三方组件,纯c#代码,在通过了156个各种各样场景的单元测试以及各种真实的业务环境验证后,今天它SqlParser.Net1.0.0正式发布了,本项目基于MIT协议开源,有以下优点,
SqlParser.Net是一个免费,功能全面且高性能的sql解析引擎类库,它可以帮助你简单快速高效的解析和处理sql。
接下来,我将介绍SqlParser.Net的用法
你可以运行以下命令在你的项目中安装 SqlParser.Net 。
PM> Install-Package SqlParser.Net
netstandard2.0
让我们一起看一个最简单的select语句是如何解析的
var sql = "select * from test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
}
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test"
}
}
}
};以上面为例子,抽象语法树的所有叶子节点均为sqlExpression的子类,且各种sqlExpression节点可以互相嵌套,组成一颗复杂无比的树,其他sql解析引擎还分为statement和expression,我认为过于复杂,所以全部统一为sqlExpression,顶级的sqlExpression总共分为4种,
这4种顶级语句中,我认为最复杂的是查询语句,因为查询组合非常多,要兼容各种各样的情况,其他3种反而非常简单。现阶段,sqlExpression的子类一共有38种,我将在下面的演示中,结合例子给大家讲解一下。
如上例子,SqlSelectExpression代表一个查询语句,SqlSelectQueryExpression则是真正具体的查询语句,他包括了
其中Columns是一个列表,他的每一个子项都是一个SqlSelectItemExpression,他的body代表一个逻辑子句,逻辑子句的值,可以为以下这些
包括order by,partition by,group by,between,in,case when后面跟着的都是逻辑子句,这个稍后会演示,在这个例子中,因为是要查询所有列,所以仅有一个SqlSelectItemExpression,他的body是SqlAllColumnExpression(代表所有列),From代表要查询的数据源,在这里仅单表查询,所以From的值为SqlTableExpression(代表单表),表名是一个SqlIdentifierExpression,即标识符表达式,表示这是一个标识符,在SQL中,标识符(Identifier)是用于命名数据库对象的名称。这些对象可以包括表、列、索引、视图、模式、数据库等。标识符使得我们能够引用和操作这些对象,在这里,标识符的值为test,表示表名为test。
var sql = "select id AS bid,t.NAME testName from test t";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "id",
},
Alias = new SqlIdentifierExpression()
{
Value = "bid",
},
},
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "NAME",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
Alias = new SqlIdentifierExpression()
{
Value = "testName",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
};
在上面这个例子中,我们指定了要查询2个字段,分别是id和t.NAME,此时Columns列表里有2个值, 第一个SqlSelectItemExpression包含了
第二个SqlSelectItemExpression的body里是一个SqlPropertyExpression,代表这是一个属性表达式,SqlPropertyExpression它包含了
合起来则代表t表的name字段,而第二个SqlSelectItemExpression也有列别名,即testName,这个查询也是单表查询,但SqlTableExpression他多了一个Alias别名字段,即表示,表别名为t。
var sql = "select 1+2 from test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlBinaryExpression()
{
Left = new SqlNumberExpression()
{
Value = 1M,
},
Operator = SqlBinaryOperator.Add,
Right = new SqlNumberExpression()
{
Value = 2M,
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
};在这个例子中,要查询的字段的值为一个二元表达式SqlBinaryExpression,他包含了
这个例子证明了,SqlSelectItemExpression代表一个逻辑子句,而不仅仅是某个字段。
var sql = "select ''' ''',3,true FROM test";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlStringExpression()
{
Value = "' '"
},
},
new SqlSelectItemExpression()
{
Body = new SqlNumberExpression()
{
Value = 3M,
},
},
new SqlSelectItemExpression()
{
Body = new SqlBoolExpression()
{
Value = true
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
};
在这个例子中,要查询的3个字段为字符串,数字和布尔值,字符串表达式即SqlStringExpression,body里即字符串的值' ',数字表达式即SqlNumberExpression,值为3,布尔表达式即SqlBoolExpression,值为true;
var sql = "select LOWER(name) FROM test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlFunctionCallExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "LOWER",
},
Arguments = new List<SqlExpression>()
{
new SqlIdentifierExpression()
{
Value = "name",
},
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
};
在这个例子中,要查询的表达式是一个函数调用,函数调用表达式即SqlFunctionCallExpression,它包含了
var sql = "SELECT t.*, ROW_NUMBER() OVER ( PARTITION BY t.ID ORDER BY t.NAME,t.ID) as rnum FROM TEST t";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "*",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
new SqlSelectItemExpression()
{
Body = new SqlFunctionCallExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "ROW_NUMBER",
},
Over = new SqlOverExpression()
{
PartitionBy = new SqlPartitionByExpression()
{
Items = new List<SqlExpression>()
{
new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "ID",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
},
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "NAME",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
new SqlOrderByItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "ID",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
},
},
},
},
Alias = new SqlIdentifierExpression()
{
Value = "rnum",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
};
在这个例子中,SqlFunctionCallExpression它除了常规字段外,还包含了Over子句,具体有以下这些
var sql = "select name,PERCENTILE_CONT(0.5) within group(order by \"number\") from TEST5 group by name";
var sqlAst = DbUtils.Parse(sql, DbType.Pgsql);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "name",
},
},
new SqlSelectItemExpression()
{
Body = new SqlFunctionCallExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "PERCENTILE_CONT",
},
WithinGroup = new SqlWithinGroupExpression()
{
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "number",
LeftQualifiers = "\"",
RightQualifiers = "\"",
},
},
},
},
},
Arguments = new List<SqlExpression>()
{
new SqlNumberExpression()
{
Value = 0.5M,
},
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST5",
},
},
GroupBy = new SqlGroupByExpression()
{
Items = new List<SqlExpression>()
{
new SqlIdentifierExpression()
{
Value = "name",
},
},
},
},
};
在这个例子中,SqlFunctionCallExpression它除了常规字段外,还包含了within group子句,具体有以下这些
var sql = "select c.*, (select a.name as province_name from portal_area a where a.id = c.province_id) as province_name, (select a.name as city_name from portal_area a where a.id = c.city_id) as city_name, (CASE WHEN c.area_id IS NULL THEN NULL ELSE (select a.name as area_name from portal_area a where a.id = c.area_id) END )as area_name from portal.portal_company c";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "*",
},
Table = new SqlIdentifierExpression()
{
Value = "c",
},
},
},
new SqlSelectItemExpression()
{
Body = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "a",
},
},
Alias = new SqlIdentifierExpression()
{
Value = "province_name",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "portal_area",
},
Alias = new SqlIdentifierExpression()
{
Value = "a",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "a",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "province_id",
},
Table = new SqlIdentifierExpression()
{
Value = "c",
},
},
},
},
},
Alias = new SqlIdentifierExpression()
{
Value = "province_name",
},
},
new SqlSelectItemExpression()
{
Body = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "a",
},
},
Alias = new SqlIdentifierExpression()
{
Value = "city_name",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "portal_area",
},
Alias = new SqlIdentifierExpression()
{
Value = "a",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "a",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "city_id",
},
Table = new SqlIdentifierExpression()
{
Value = "c",
},
},
},
},
},
Alias = new SqlIdentifierExpression()
{
Value = "city_name",
},
},
new SqlSelectItemExpression()
{
Body = new SqlCaseExpression()
{
Items = new List<SqlCaseItemExpression>()
{
new SqlCaseItemExpression()
{
Condition = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "area_id",
},
Table = new SqlIdentifierExpression()
{
Value = "c",
},
},
Operator = SqlBinaryOperator.Is,
Right = new SqlNullExpression()
},
Value = new SqlNullExpression()
},
},
Else = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "a",
},
},
Alias = new SqlIdentifierExpression()
{
Value = "area_name",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "portal_area",
},
Alias = new SqlIdentifierExpression()
{
Value = "a",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "a",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "area_id",
},
Table = new SqlIdentifierExpression()
{
Value = "c",
},
},
},
},
},
},
Alias = new SqlIdentifierExpression()
{
Value = "area_name",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "portal_company",
},
Schema = new SqlIdentifierExpression()
{
Value = "portal",
},
Alias = new SqlIdentifierExpression()
{
Value = "c",
},
},
},
};
在这个例子中,要查询的列值为一个SqlSelectExpression表达式,即要查询的列是一个子查询
var sql = "SELECT * FROM test WHERE ID =1";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "ID",
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlNumberExpression()
{
Value = 1M,
},
},
},
};
在这个例子中,where字段的值是一个二元表达式SqlBinaryExpression,他包含了
二元表达式的两边可以非常灵活,可以是各种其他表达式,同时也可以自我嵌套另一个二元表达式,组成一个非常复杂的二元表达式
var sql = "SELECT * FROM test WHERE ID BETWEEN 1 AND 2";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
Where = new SqlBetweenAndExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "ID",
},
Begin = new SqlNumberExpression()
{
Value = 1M,
},
End = new SqlNumberExpression()
{
Value = 2M,
},
},
},
};
between子句包含了
var sql = "select * from test rd where rd.name is null";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
Alias = new SqlIdentifierExpression()
{
Value = "rd",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "rd",
},
},
Operator = SqlBinaryOperator.Is,
Right = new SqlNullExpression()
},
},
};
is null/is not null子句主要体现在二元表达式里,Operator字段为Is/IsNot,right字段为SqlNullExpression,即null表达式,代表值为null
var sql = "select * from TEST t where EXISTS(select * from TEST2 t2)";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
Where = new SqlExistsExpression()
{
Body = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST2",
},
Alias = new SqlIdentifierExpression()
{
Value = "t2",
},
},
},
},
},
},
};
exists/not exists子句,主要体现为SqlExistsExpression表达式,
var sql = "SELECT * from TEST t WHERE name LIKE '%a%'";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "name",
},
Operator = SqlBinaryOperator.Like,
Right = new SqlStringExpression()
{
Value = "%a%"
},
},
},
};
like子句,主要体现在二元表达式里,Operator字段为Like/NotLike,本例子中right字段为字符串表达式,即SqlStringExpression表达式,值为%a%。
var sql = "select * from customer c where c.Age >all(select o.Quantity from orderdetail o)";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "customer",
},
Alias = new SqlIdentifierExpression()
{
Value = "c",
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "Age",
},
Table = new SqlIdentifierExpression()
{
Value = "c",
},
},
Operator = SqlBinaryOperator.GreaterThen,
Right = new SqlAllExpression()
{
Body = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "Quantity",
},
Table = new SqlIdentifierExpression()
{
Value = "o",
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "orderdetail",
},
Alias = new SqlIdentifierExpression()
{
Value = "o",
},
},
},
},
},
},
},
};
all/any子句,主要体现在SqlAllExpression/SqlAnyExpression表达式,它的body里是另一个SqlSelectExpression表达式
var sql = "SELECT * from TEST t WHERE t.NAME IN ('a','b','c')";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
Where = new SqlInExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "NAME",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
TargetList = new List<SqlExpression>()
{
new SqlStringExpression()
{
Value = "a"
},
new SqlStringExpression()
{
Value = "b"
},
new SqlStringExpression()
{
Value = "c"
},
},
},
},
};
in/not in子句,主要体现在SqlInExpression表达式,它包含了
当然了,in也有另一种子查询的类型,即
var sql = "select * from TEST5 WHERE NAME IN (SELECT NAME FROM TEST3)";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST5",
},
},
Where = new SqlInExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "NAME",
},
SubQuery = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "NAME",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST3",
},
},
},
},
},
},
};在这里的SqlInExpression表达式中,它包含了
var sql = "SELECT CASE WHEN t.name='1' THEN 'a' WHEN t.name='2' THEN 'b' ELSE 'c' END AS v from TEST t";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlCaseExpression()
{
Items = new List<SqlCaseItemExpression>()
{
new SqlCaseItemExpression()
{
Condition = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "1"
},
},
Value = new SqlStringExpression()
{
Value = "a"
},
},
new SqlCaseItemExpression()
{
Condition = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "2"
},
},
Value = new SqlStringExpression()
{
Value = "b"
},
},
},
Else = new SqlStringExpression()
{
Value = "c"
},
},
Alias = new SqlIdentifierExpression()
{
Value = "v",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
};
case when子句,主要体现在SqlCaseExpression表达式里,他包含了
case when还有另外一种句式,如下:
var sql = "select case t.name when 'a' then 1 else 2 end from test t ";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlCaseExpression()
{
Items = new List<SqlCaseItemExpression>()
{
new SqlCaseItemExpression()
{
Condition = new SqlStringExpression()
{
Value = "a"
},
Value = new SqlNumberExpression()
{
Value = 1M,
},
},
},
Else = new SqlNumberExpression()
{
Value = 2M,
},
Value = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
};
在这种SqlCaseExpression表达式里,他包含了
var sql = "select * from TEST t WHERE not t.NAME ='abc'";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
Where = new SqlNotExpression()
{
Body = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "NAME",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "abc"
},
},
},
},
};
not子句,主要体现在SqlNotExpression表达式里,它只有一个body字段,即代表否定的部分
var sql = "select * from TEST t WHERE not t.NAME =:name";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
Where = new SqlNotExpression()
{
Body = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "NAME",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlVariableExpression()
{
Name = "name",
Prefix = ":",
},
},
},
},
};
变量子句,主要体现在SqlVariableExpression表达式里,它包括以下部分:
在sql中,From关键字后面有多种形式来指定数据源。主要有以下几种
select * from test这个解析结果上面已经演示了。
var sql = "select * from (select * from test) t";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlSelectExpression()
{
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
},
},
};
在这个例子中,数据源From的值为一个SqlSelectExpression,即SqlSelectExpression中可以嵌套SqlSelectExpression,同时我们注意到内部的SqlSelectExpression有一个表别名的字段Alias,标识符的值为t,表示表别名为t;
var sql = "select t1.id from test t1 left join test2 t2 on t1.id=t2.id right join test3 t3 on t2.id=t3.id";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "t1",
},
},
},
},
From = new SqlJoinTableExpression()
{
Left = new SqlJoinTableExpression()
{
Left = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
Alias = new SqlIdentifierExpression()
{
Value = "t1",
},
},
JoinType = SqlJoinType.LeftJoin,
Right = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test2",
},
Alias = new SqlIdentifierExpression()
{
Value = "t2",
},
},
Conditions = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "t1",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "t2",
},
},
},
},
JoinType = SqlJoinType.RightJoin,
Right = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test3",
},
Alias = new SqlIdentifierExpression()
{
Value = "t3",
},
},
Conditions = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "t2",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "id",
},
Table = new SqlIdentifierExpression()
{
Value = "t3",
},
},
},
},
},
};
在上面这个例子中,我们演示了连表查询是如何解析的,From字段的值为一个SqlJoinTableExpression,即连表查询表达式,他包含了
在这个例子中,总共3张表联查,SqlJoinTableExpression中得left字段又是一个SqlJoinTableExpression,即SqlJoinTableExpression中可以嵌套SqlJoinTableExpression,无限套娃。
var sql = "with c1 as (select name from test t) , c2(name) AS (SELECT name FROM TEST2 t3 ) select *from c1 JOIN c2 ON c1.name=c2.name";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
WithSubQuerys = new List<SqlWithSubQueryExpression>()
{
new SqlWithSubQueryExpression()
{
Alias = new SqlIdentifierExpression()
{
Value = "c1",
},
FromSelect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "name",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
},
},
new SqlWithSubQueryExpression()
{
Alias = new SqlIdentifierExpression()
{
Value = "c2",
},
FromSelect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "name",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST2",
},
Alias = new SqlIdentifierExpression()
{
Value = "t3",
},
},
},
},
Columns = new List<SqlIdentifierExpression>()
{
new SqlIdentifierExpression()
{
Value = "name",
},
},
},
},
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlJoinTableExpression()
{
Left = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "c1",
},
},
JoinType = SqlJoinType.InnerJoin,
Right = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "c2",
},
},
Conditions = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "c1",
},
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "c2",
},
},
},
},
},
};
公用表表达式(CTE),主要体现在SqlSelectQueryExpression的WithSubQuerys字段,他是一个SqlWithSubQueryExpression表达式列表,即公用表列表,它里面的每一个元素都是SqlWithSubQueryExpression表达式,此表达式,包含了
特定数据库支持从返回结果集的函数中查询,比如oracle中添加一个自定义函数splitstr,他的作用是将一个字符串根据;号进行分割,返回多行数据
var sql = "SELECT * FROM TABLE(splitstr('a;b',';'))";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlReferenceTableExpression()
{
FunctionCall = new SqlFunctionCallExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TABLE",
},
Arguments = new List<SqlExpression>()
{
new SqlFunctionCallExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "splitstr",
},
Arguments = new List<SqlExpression>()
{
new SqlStringExpression()
{
Value = "a;b"
},
new SqlStringExpression()
{
Value = ";"
},
},
},
},
},
}
},
};
函数返回的结果集主要体现在SqlReferenceTableExpression表达式,他的内部包含了一个FunctionCall字段,值为SqlFunctionCallExpression表达式,代表从函数调用的结果集中进行查询。
var sql = "select fa.FlowId from FlowActivity fa order by fa.FlowId desc,fa.Id asc";
var sqlAst = DbUtils.Parse(sql, DbType.SqlServer);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "FlowId"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "FlowActivity"
},
Alias = new SqlIdentifierExpression()
{
Value = "fa"
},
},
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
Body =
new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "FlowId"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
OrderByType = SqlOrderByType.Desc
},
new SqlOrderByItemExpression()
{
Body =
new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "Id"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
OrderByType = SqlOrderByType.Asc
},
},
},
},
};
OrderBy排序子句,值为SqlOrderByExpression表达式,表达式的内容也非常简单,只有一个Items,即一个排序子项表达式的列表,列表里的值为SqlOrderByItemExpression,即排序子项表达式,排序子项表达式里又包含了以下内容
select * from TEST5 t order by t.NAME desc nulls FIRST,t.AGE ASC NULLS last 那么我们的NullsType字段,他的值有SqlOrderByNullsType.First和SqlOrderByNullsType.Last,与之对应。
var sql = "select fa.FlowId from FlowActivity fa group by fa.FlowId,fa.Id HAVING count(fa.Id)>1";
var sqlAst = DbUtils.Parse(sql, DbType.SqlServer);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "FlowId"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "FlowActivity"
},
Alias = new SqlIdentifierExpression()
{
Value = "fa"
},
},
GroupBy = new SqlGroupByExpression()
{
Items = new List<SqlExpression>()
{
new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "FlowId"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "Id"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
},
Having = new SqlBinaryExpression()
{
Left = new SqlFunctionCallExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "count"
},
Arguments = new List<SqlExpression>()
{
new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "Id"
},
Table = new SqlIdentifierExpression()
{
Value = "fa"
},
},
},
},
Operator = SqlBinaryOperator.GreaterThen,
Right = new SqlNumberExpression()
{
Value = 1M
},
},
},
},
};
GroupBy分组语句,值为SqlGroupByExpression表达式,他的内容如下
var sql = "select * from test t limit 1,5";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
Limit = new SqlLimitExpression()
{
Offset = new SqlNumberExpression()
{
Value = 1M,
},
RowCount = new SqlNumberExpression()
{
Value = 5M,
},
},
},
};
Limit分页子句,值为SqlLimitExpression表达式,他的内容如下
var sql = "SELECT * FROM TEST3 t ORDER BY t.NAME DESC FETCH FIRST 2 rows ONLY";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
}
},
From = new SqlTableExpression()
{
Alias = new SqlIdentifierExpression()
{
Value = "t"
},
Name = new SqlIdentifierExpression()
{
Value = "TEST3"
}
},
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
OrderByType = SqlOrderByType.Desc,
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression() { Value = "NAME" },
Table = new SqlIdentifierExpression()
{
Value = "t"
}
}
}
}
},
Limit = new SqlLimitExpression()
{
RowCount = new SqlNumberExpression()
{
Value = 2
}
}
}
};
var sql = "select * from test5 t order by t.name limit 1 offset 10;";
var sqlAst = DbUtils.Parse(sql, DbType.Pgsql);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test5",
},
Alias = new SqlIdentifierExpression()
{
Value = "t",
},
},
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "name",
},
Table = new SqlIdentifierExpression()
{
Value = "t",
},
},
},
},
},
Limit = new SqlLimitExpression()
{
Offset = new SqlNumberExpression()
{
Value = 10M,
},
RowCount = new SqlNumberExpression()
{
Value = 1M,
},
},
},
};
var sql = "select * from test t order by t.name OFFSET 5 ROWS FETCH NEXT 10 ROWS ONLY";
var sqlAst = DbUtils.Parse(sql, DbType.SqlServer);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
}
},
From = new SqlTableExpression()
{
Alias = new SqlIdentifierExpression()
{
Value = "t"
},
Name = new SqlIdentifierExpression()
{
Value = "test"
}
},
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
Body = new SqlPropertyExpression()
{
Name = new SqlIdentifierExpression() { Value = "name" },
Table = new SqlIdentifierExpression()
{
Value = "t"
}
}
}
}
},
Limit = new SqlLimitExpression()
{
Offset = new SqlNumberExpression()
{
Value = 5
},
RowCount = new SqlNumberExpression()
{
Value = 10
}
}
}
};
var sql = "SELECT EMPLOYEEID , MANAGERID , LEVEL FROM EMPLOYEE e START WITH MANAGERID IS NULL CONNECT BY NOCYCLE PRIOR EMPLOYEEID = MANAGERID ORDER SIBLINGS BY EMPLOYEEID ";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "EMPLOYEEID",
},
},
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "MANAGERID",
},
},
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "LEVEL",
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "EMPLOYEE",
},
Alias = new SqlIdentifierExpression()
{
Value = "e",
},
},
ConnectBy = new SqlConnectByExpression()
{
StartWith = new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "MANAGERID",
},
Operator = SqlBinaryOperator.Is,
Right = new SqlNullExpression()
},
Body = new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "EMPLOYEEID",
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlIdentifierExpression()
{
Value = "MANAGERID",
},
},
IsNocycle = true,
IsPrior = true,
OrderBy = new SqlOrderByExpression()
{
Items = new List<SqlOrderByItemExpression>()
{
new SqlOrderByItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "EMPLOYEEID",
},
},
},
IsSiblings = true,
},
},
},
};
ConnectBy层次查询子句,值为SqlConnectByExpression表达式,他的内容如下
var sql = "SELECT name into test14 from TEST as t ";
var sqlAst = DbUtils.Parse(sql, DbType.SqlServer);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "name"
},
},
},
Into = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test14"
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST"
},
Alias = new SqlIdentifierExpression()
{
Value = "t"
},
},
},
};
into子句,在本例子中值为SqlTableExpression,即into到某张表里。
var sql = "insert into test11(name,id) values('a1','a2')";
var sqlAst = DbUtils.Parse(sql, DbType.SqlServer);解析结果如下:
var expect = new SqlInsertExpression()
{
Columns = new List<SqlExpression>()
{
new SqlIdentifierExpression()
{
Value = "name"
},
new SqlIdentifierExpression()
{
Value = "id"
},
},
ValuesList = new List<List<SqlExpression>>()
{
new List<SqlExpression>()
{
new SqlStringExpression()
{
Value = "a1"
},
new SqlStringExpression()
{
Value = "a2"
},
},
},
Table = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test11"
},
},
};
如上例子,插入语句表现为一个SqlInsertExpression,他包含了
为什么ValuesList字段是列表里嵌套列表呢?主要是因为可以插入多个值列表,让我们继续往下看
var sql = "insert into test11(name,id) values('a1','a2'),('a3','a4')";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlInsertExpression()
{
Columns = new List<SqlExpression>()
{
new SqlIdentifierExpression()
{
Value = "name"
},
new SqlIdentifierExpression()
{
Value = "id"
},
},
ValuesList = new List<List<SqlExpression>>()
{
new List<SqlExpression>()
{
new SqlStringExpression()
{
Value = "a1"
},
new SqlStringExpression()
{
Value = "a2"
},
},
new List<SqlExpression>()
{
new SqlStringExpression()
{
Value = "a3"
},
new SqlStringExpression()
{
Value = "a4"
},
},
},
Table = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test11"
},
},
};
在本例子中,ValuesList字段中有2个子元素,即2个List列表,代表插入2组数据,值分别为('a1','a2')和('a3','a4')
var sql = "INSERT INTO TEST2(name) SELECT name AS name2 FROM TEST t";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlInsertExpression()
{
Columns = new List<SqlExpression>()
{
new SqlIdentifierExpression()
{
Value = "name"
},
},
Table = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST2"
},
},
FromSelect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlIdentifierExpression()
{
Value = "name"
},
Alias = new SqlIdentifierExpression()
{
Value = "name2"
},
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "TEST"
},
Alias = new SqlIdentifierExpression()
{
Value = "t"
},
},
},
},
};
如上例子,插入语句表现为一个SqlInsertExpression,他包含了
var sql = "update test set name ='4',d='2024-11-22 08:19:47.243' where name ='1'";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlUpdateExpression()
{
Table = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test"
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "name"
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "1"
},
},
Items = new List<SqlExpression>()
{
new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "name"
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "4"
},
},
new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "d"
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "2024-11-22 08:19:47.243"
},
},
},
};如上例子,更新语句表现为一个SqlUpdateExpression,他包含了
var sql = "delete from test where name=4";
var sqlAst = DbUtils.Parse(sql, DbType.MySql);解析结果如下:
var expect = new SqlDeleteExpression()
{
Table = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test"
},
},
Where = new SqlBinaryExpression()
{
Left = new SqlIdentifierExpression()
{
Value = "name"
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlNumberExpression()
{
Value = 4M
},
},
};如上例子,删除语句表现为一个SqlDeleteExpression,他包含了
var sql = @"select *--abc from test lbu WHERE a ='1'--aaaaaa
FROM test";
var sqlAst = DbUtils.Parse(sql, DbType.SqlServer);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
};如上例子,单行注释被正确忽视,解析正确。
var sql = @"/*这
是
顶部*/
select *--abc
FROM test/*这
是
底部*/";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析结果如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
};
如上例子,多行注释被正确忽视,解析正确。
当我们通过
var sql = @"select * from test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析sql获取到抽象语法树以后,我们就要对这颗抽象语法树进行解析,获取我们想要的数据,此时就要用上访问者模式(visitor) .
访问者模式最大的特点就是结构与算法分离,结合本项目理解,就是ast抽象语法树这个结构已经解析出来了,你可以根据自己的需要写算法去任意解析这颗语法树。这是一个1-N的操作,即一个抽象语法树,可以对应N个解析算法,当我们要自定义算法去解析抽象语法树时,我们需要自定义一个Visitor类,并且实现IAstVisitor接口
public class CustomVisitor : IAcceptVisitor
{
}但是实现这个接口要实现接口里的很多个方法,并且有些数据并不是我们关心的,所以我提供了一个实现了IAcceptVisitor接口的抽象类BaseAstVisitor用来简化操作,我们只需要继承这个抽象类,然后重写我们感兴趣的方法即可
public class CustomVisitor : BaseAstVisitor
{
}在本项目中,我提供了2个基本的vistor供大家使用,UnitTestAstVisitor和SqlGenerationAstVisitor,大家可以参考这2个visitor去写自己的算法来解析抽象语法树。接下来,我将介绍这2个visitor的用法。
当我们通过
var sql = @"select * from test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);解析sql获取到抽象语法树之后,sqlAst其实还是一个数据结构,我们可以通过vs监视这个变量来查看内部的结构,但是如果是非常复杂的sql,那这颗树会巨大无比,要靠我们手动去慢慢点开查看得累死,没错!写单元测试的时候,我刚开始都是用手写的结果去对比引擎解析出来的结果,后来我就被累死了,该说不说,这活真不是人干的,所以痛定思痛之后我就写了这个UnitTestAstVisitor来替我生成ast的结构字符串,接下来让我们看看用法
var sql = @"select * from test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);
var unitTestAstVisitor = new UnitTestAstVisitor();
sqlAst.Accept(unitTestAstVisitor);
var result = unitTestAstVisitor.GetResult();其中的result就是解析抽象语法树生成的字符串,如下:
var expect = new SqlSelectExpression()
{
Query = new SqlSelectQueryExpression()
{
Columns = new List<SqlSelectItemExpression>()
{
new SqlSelectItemExpression()
{
Body = new SqlAllColumnExpression()
},
},
From = new SqlTableExpression()
{
Name = new SqlIdentifierExpression()
{
Value = "test",
},
},
},
};然后把这个生成的字符串黏贴到vs里去和引擎生成的结果进行对比,
Assert.True(sqlAst.Equals(expect));至此,我写单元测试的工作量大大减轻,同时对于生成的sqlAst语法树的结构也更加一目了然了。
我们通过解析sql生成了抽象语法树之后,如果我们想要给这颗抽象语法树添加一个where条件,比如添加test.name ='a'
var sql = @"select * from test";
var sqlAst = DbUtils.Parse(sql, DbType.Oracle);
if (sqlAst is SqlSelectExpression sqlSelectExpression && sqlSelectExpression.Query is SqlSelectQueryExpression sqlSelectQueryExpression)
{
sqlSelectQueryExpression.Where = new SqlBinaryExpression()
{
Left = new SqlPropertyExpression()
{
Table = new SqlIdentifierExpression()
{
Value = "test"
},
Name = new SqlIdentifierExpression()
{
Value = "name"
}
},
Operator = SqlBinaryOperator.EqualTo,
Right = new SqlStringExpression()
{
Value = "a"
}
};
}好了,现在我们添加完了,接下来我们肯定是想着把抽象语法树转化为sql语句,此时,就需要用上SqlGenerationAstVisitor了,他就是负责把抽象语法树转化为sql的
var sqlGenerationAstVisitor = new SqlGenerationAstVisitor(DbType.Oracle);
sqlAst.Accept(sqlGenerationAstVisitor);
var newSql = sqlGenerationAstVisitor.GetResult();我们获取到的newSql就是新的sql了,他的值为
select * from test where(test.name = 'a')至此,我们的目的就达到了。
sql之所以能被我们解析出来,主要是因为sql是一种形式语言,自然语言和形式语言的一个重要区别是,自然语言的一个语句,可能有多重含义,而形式语言的一个语句,只能有一个语义;形式语言的语法是人为规定的,有了一定的语法规则,语法解析器就能根据语法规则,解析出一个语句的唯一含义。
本项目基于MIT协议开源,地址为 https://github.com/TripleView/SqlParser.Net
同时感谢以下项目
如果各位靓仔觉得这个项目不错,欢迎一键三连(推荐,star,关注),同时欢迎加入三合的开源交流群,QQ群号:799648362
