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259 lines
12 KiB
Markdown
259 lines
12 KiB
Markdown
# 查询数据
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## 测试代码
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```csharp
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IFreeSql fsql = new FreeSql.FreeSqlBuilder()
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.UseConnectionString(FreeSql.DataType.MySql, "Data Source=127.0.0.1;Port=3306;User ID=root;Password=root;Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=10")
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.Build();
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ISelect<Topic> select => fsql.Select<Topic>();
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[Table(Name = "tb_topic")]
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class Topic {
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[Column(IsIdentity = true, IsPrimary = true)]
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public int Id { get; set; }
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public int Clicks { get; set; }
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public int TestTypeInfoGuid { get; set; }
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public TestTypeInfo Type { get; set; }
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public string Title { get; set; }
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public DateTime CreateTime { get; set; }
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}
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class TestTypeInfo {
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public int Guid { get; set; }
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public int ParentId { get; set; }
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public TestTypeParentInfo Parent { get; set; }
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public string Name { get; set; }
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}
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class TestTypeParentInfo {
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public int Id { get; set; }
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public string Name { get; set; }
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public List<TestTypeInfo> Types { get; set; }
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}
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```
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# Where
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### 单表
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```csharp
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var sql = select.Where(a => a.Id == 10).ToSql();
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///SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a.`Title`, a.`CreateTime` FROM `tb_topic` a WHERE (a.`Id` = 10)
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sql = select.Where(a => a.Id == 10 && a.Id > 10 || a.Clicks > 100).ToSql();
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///SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a.`Title`, a.`CreateTime` FROM `tb_topic` a WHERE (a.`Id` = 10 AND a.`Id` > 10 OR a.`Clicks` > 100)
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sql = select.Where(a => new []{1,2,3}.Contains(a.Id)).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a.`Title`, a.`CreateTime` FROM `tb_topic` a WHERE (a.`Id` in (1,2,3))
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```
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> [《Expression 表达式函数文档》](Docs/expression.md)
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### 多表，使用导航属性
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```csharp
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sql = select.Where(a => a.Type.Name == "typeTitle" && a.Type.Guid == a.TestTypeInfoGuid).ToSql();
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///SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a__Type.`Guid`, a__Type.`ParentId`, a__Type.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a, `TestTypeInfo` a__Type WHERE (a__Type.`Name` = 'typeTitle' AND a__Type.`Guid` = a.`TestTypeInfoGuid`)
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sql = select.Where(a => a.Type.Parent.Name == "tparent").ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a__Type.`Guid`, a__Type.`ParentId`, a__Type.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a, `TestTypeInfo` a__Type, `TestTypeParentInfo` a__Type__Parent WHERE (a__Type__Parent.`Name` = 'tparent')
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```
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### 多表，没有导航属性
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```csharp
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sql = select.Where<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid && b.Name == "typeTitle").ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, b.`Guid`, b.`ParentId`, b.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a, `TestTypeInfo` b WHERE (b.`Guid` = a.`TestTypeInfoGuid` AND b.`Name` = 'typeTitle')
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sql = select.Where<TestTypeInfo, TestTypeParentInfo>((a, b, c) => c.Name == "tparent").ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a.`Title`, a.`CreateTime` FROM `tb_topic` a, `TestTypeParentInfo` c WHERE (c.`Name` = 'tparent')
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```
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### 多表，任意查
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```csharp
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sql = select.From<TestTypeInfo, TestTypeParentInfo>((s, b, c) => s
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.Where(a => a.Id == 10 && c.Name == "xxx")
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.Where(a => b.ParentId == 20)).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, b.`Guid`, b.`ParentId`, b.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a, `TestTypeParentInfo` c, `TestTypeInfo` b WHERE (a.`Id` = 10 AND c.`Name` = 'xxx') AND (b.`ParentId` = 20)
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```
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### 子表 Exists 查询
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```csharp
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var sql2222 = select.Where(a => select.Where(b => b.Id == a.Id).Any()).ToList();
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// SELECT a.`Id`, a.`TypeGuid`, a.`Title`, a.`CreateTime`
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// FROM `xxx` a
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// WHERE (exists(SELECT 1
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// FROM `xxx` b
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// WHERE (b.`Id` = a.`Id`)))
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//两级相同的子表查询
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sql2222 = select.Where(a =>
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select.Where(b => b.Id == a.Id && select.Where(c => c.Id == b.Id).Where(d => d.Id == a.Id).Where(e => e.Id == b.Id)
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.Offset(a.Id)
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.Any()
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).Any()
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).ToList();
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// SELECT a.`Id`, a.`TypeGuid`, a.`Title`, a.`CreateTime`
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// FROM `xxx` a
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// WHERE (exists(SELECT 1
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// FROM `xxx` b
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// WHERE (b.`Id` = a.`Id` AND exists(SELECT 1
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// FROM `xxx` c
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// WHERE (c.`Id` = b.`Id`) AND (c.`Id` = a.`Id`) AND (c.`Id` = b.`Id`)
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// limit 0,1))
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// limit 0,1))
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```
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### 原生SQL
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```csharp
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sql = select.Where("a.clicks > 100 && a.id = ?id", new { id = 10 }).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a.`Title`, a.`CreateTime` FROM `tb_topic` a WHERE (a.clicks > 100 && a.id = ?id)
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```
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> 以上条件查询，支持 WhereIf
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# 联表
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### 使用导航属性联表
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```csharp
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sql = select.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a__Type.`Guid`, a__Type.`ParentId`, a__Type.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a LEFT JOIN `TestTypeInfo` a__Type ON a__Type.`Guid` = a.`TestTypeInfoGuid`
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sql = select
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.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid)
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.LeftJoin(a => a.Type.Parent.Id == a.Type.ParentId).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a__Type.`Guid`, a__Type.`ParentId`, a__Type.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a LEFT JOIN `TestTypeInfo` a__Type ON a__Type.`Guid` = a.`TestTypeInfoGuid` LEFT JOIN `TestTypeParentInfo` a__Type__Parent ON a__Type__Parent.`Id` = a__Type.`ParentId`
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```
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### 没有导航属性联表
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```csharp
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sql = select.LeftJoin<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, b.`Guid`, b.`ParentId`, b.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a LEFT JOIN `TestTypeInfo` b ON b.`Guid` = a.`TestTypeInfoGuid`
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sql = select
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.LeftJoin<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid)
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.LeftJoin<TestTypeParentInfo>((a, c) => c.Id == a.Type.ParentId).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, b.`Guid`, b.`ParentId`, b.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a LEFT JOIN `TestTypeInfo` b ON b.`Guid` = a.`TestTypeInfoGuid` LEFT JOIN `TestTypeParentInfo` c ON c.`Id` = b.`ParentId`
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```
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### 联表任意查
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```csharp
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sql = select.From<TestTypeInfo, TestTypeParentInfo>((s, b, c) => s
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.LeftJoin(a => a.TestTypeInfoGuid == b.Guid)
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.LeftJoin(a => b.ParentId == c.Id)).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, b.`Guid`, b.`ParentId`, b.`Name`, a.`Title`, a.`CreateTime` FROM `tb_topic` a LEFT JOIN `TestTypeInfo` b ON a.`TestTypeInfoGuid` = b.`Guid` LEFT JOIN `TestTypeParentInfo` c ON b.`ParentId` = c.`Id`
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```
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### 原生SQL联表
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```csharp
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sql = select.LeftJoin("TestTypeInfo b on b.Guid = a.TestTypeInfoGuid and b.Name = ?bname", new { bname = "xxx" }).ToSql();
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//SELECT a.`Id`, a.`Clicks`, a.`TestTypeInfoGuid`, a.`Title`, a.`CreateTime` FROM `tb_topic` a LEFT JOIN TestTypeInfo b on b.Guid = a.TestTypeInfoGuid and b.Name = ?bname
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```
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# 查询数据
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### 返回 List
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```csharp
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List<Topic> t1 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList();
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```
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### 返回 List + 导航属性的数据
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```csharp
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List<Topic> t2 = select.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid).ToList();
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//此时会返回普通字段 + 导航对象 Type 的数据
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```
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### 指定字段返回
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```csharp
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//返回一个字段
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List<int> t3 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList(a => a.Id);
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//返回匿名类
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List<匿名类> t4 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList(a => new { a.Id, a.Title });
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//返回元组
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List<(int, string)> t5 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList<(int, string)>("id, title");
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//返回SQL字段
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List<匿名类> t4 = select.Where(a => a.Id > 0).Skip(100).Limit(200)
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.ToList(a => new {
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a.Id,
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a.Title,
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cstitle = "substr(a.title, 0, 2)", //将 substr(a.title, 0, 2) 作为查询字段
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csnow = Convert.ToDateTime("now()"), //将 now() 作为查询字段
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//奇思妙想：怎么查询开窗函数的结果
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});
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```
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### 执行SQL返回数据
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```csharp
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class xxx {
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public int Id { get; set; }
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public string Path { get; set; }
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public string Title2 { get; set; }
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}
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List<xxx> t6 = fsql.Ado.Query<xxx>("select * from song");
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List<(int, string ,string)> t7 = fsql.Ado.Query<(int, string, string)>("select * from song");
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List<dynamic> t8 = fsql.Ado.Query<dynamic>("select * from song");
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```
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### 分组聚合
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```csharp
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var groupby = fsql.Select<Topic>()
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.GroupBy(a => new { tt2 = a.Title.Substring(0, 2), mod4 = a.Id % 4 })
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.Having(a => a.Count() > 0 && a.Avg(a.Key.mod4) > 0 && a.Max(a.Key.mod4) > 0)
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.Having(a => a.Count() < 300 || a.Avg(a.Key.mod4) < 100)
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.OrderBy(a => a.Key.tt2)
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.OrderByDescending(a => a.Count())
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.ToList(a => new { a.Key.tt2, cou1 = a.Count(), arg1 = a.Avg(a.Key.mod4) });
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//SELECT substr(a.`Title`, 1, 2) as1, count(1) as2, avg((a.`Id` % 4)) as3
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//FROM `xxx` a
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//GROUP BY substr(a.`Title`, 1, 2), (a.`Id` % 4)
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//HAVING (count(1) > 0 AND avg((a.`Id` % 4)) > 0 AND max((a.`Id` % 4)) > 0) AND (count(1) < 300 OR avg((a.`Id` % 4)) < 100)
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//ORDER BY substr(a.`Title`, 1, 2), count(1) DESC
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```
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# 更多文档整理中。。。
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| 方法 | 返回值 | 参数 | 描述 |
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| ------------- | - | - | - |
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| ToSql | string | | 返回即将执行的SQL语句 |
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| ToList | List<T1> | | 执行SQL查询，返回 T1 实体所有字段的记录，若存在导航属性则一起查询返回，记录不存在时返回 Count 为 0 的列表 |
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| ToList\<T\> | List\<T\> | Lambda | 执行SQL查询，返回指定字段的记录，记录不存在时返回 Count 为 0 的列表 |
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| ToList\<T\> | List\<T\> | string field | 执行SQL查询，返回 field 指定字段的记录，并以元组或基础类型(int,string,long)接收，记录不存在时返回 Count 为 0 的列表 |
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| ToOne | T1 | | 执行SQL查询，返回 T1 实体所有字段的第一条记录，记录不存在时返回 null |
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| Any | bool | | 执行SQL查询，是否有记录 |
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| Sum | T | Lambda | 指定一个列求和 |
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| Min | T | Lambda | 指定一个列求最小值 |
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| Max | T | Lambda | 指定一个列求最大值 |
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| Avg | T | Lambda | 指定一个列求平均值 |
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| 【分页】 |
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| Count | long | | 查询的记录数量 |
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| Count | \<this\> | out long | 查询的记录数量，以参数out形式返回 |
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| Skip | \<this\> | int offset | 查询向后偏移行数 |
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| Offset | \<this\> | int offset | 查询向后偏移行数 |
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| Limit | \<this\> | int limit | 查询多少条数据 |
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| Take | \<this\> | int limit | 查询多少条数据 |
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| Page | \<this\> | int pageIndex, int pageSize | 分页 |
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| 【条件】 |
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| Where | \<this\> | Lambda | 支持多表查询表达式 |
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| WhereIf | \<this\> | bool, Lambda | 支持多表查询表达式 |
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| Where | \<this\> | string, parms | 原生sql语法条件，Where("id = ?id", new { id = 1 }) |
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| WhereIf | \<this\> | bool, string, parms | 原生sql语法条件，WhereIf(true, "id = ?id", new { id = 1 }) |
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| 【分组】 |
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| GroupBy | \<this\> | Lambda | 按选择的列分组，GroupBy(a => a.Name) | GroupBy(a => new{a.Name,a.Time}) |
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| GroupBy | \<this\> | string, parms | 按原生sql语法分组，GroupBy("concat(name, ?cc)", new { cc = 1 }) |
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| Having | \<this\> | string, parms | 按原生sql语法聚合条件过滤，Having("count(name) = ?cc", new { cc = 1 }) |
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| 【排序】 |
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| OrderBy | \<this\> | Lambda | 按列排序，OrderBy(a => a.Time) |
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| OrderByDescending | \<this\> | Lambda | 按列倒向排序，OrderByDescending(a => a.Time) |
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| OrderBy | \<this\> | string, parms | 按原生sql语法排序，OrderBy("count(name) + ?cc", new { cc = 1 }) |
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| 【联表】 |
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| LeftJoin | \<this\> | Lambda | 左联查询，可使用导航属性，或指定关联的实体类型 |
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| InnerJoin | \<this\> | Lambda | 联接查询，可使用导航属性，或指定关联的实体类型 |
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| RightJoin | \<this\> | Lambda | 右联查询，可使用导航属性，或指定关联的实体类型 |
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| LeftJoin | \<this\> | string, parms | 左联查询，使用原生sql语法，LeftJoin("type b on b.id = a.id and b.clicks > ?clicks", new { clicks = 1 }) |
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| InnerJoin | \<this\> | string, parms | 联接查询，使用原生sql语法，InnerJoin("type b on b.id = a.id and b.clicks > ?clicks", new { clicks = 1 }) |
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| RightJoin | \<this\> | string, parms | 右联查询，使用原生sql语法，RightJoin("type b on b.id = a.id and b.clicks > ?clicks", new { clicks = 1 }) |
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| From | \<this\> | Lambda | 多表查询，3个表以上使用非常方便，目前设计最大支持10个表 |
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| 【其他】 |
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| As | \<this\> | string alias = "a" | 指定别名 |
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| Master | \<this\> | | 指定从主库查询（默认查询从库） |
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| Caching | \<this\> | int seconds, string key = null | 缓存查询结果 | |