联表逻辑查询

• 联表查询数据
• 联表由多个别名表联接而成
• 在多表逻辑查询基础上增加了JoinOn
• 需要逻辑联表关联配合使用
• WHERE查询部分与多表逻辑查询类似

1. 接口

• IJoinTable
• IMultiView
• IDataQuery

2. 基类

MultiTableBase

3. 类

JoinTableQuery

4. 示例

4.1 自定义别名表

CommentAliasTable c = new("c");
PostAliasTable p = new("p");
var joinOn = JoinOnQuery.Create(c, p)
    .And(c.PostId.Equal(p.Id));
JoinTableQuery query = joinOn.Root
    .And(c.Pick.EqualValue(true))
    .And(p.Author.EqualValue("张三"));

SELECT * FROM [Comments] AS c INNER JOIN [Posts] AS p ON c.[PostId]=p.[Id] WHERE c.[Pick]=1 AND p.[Author]='张三'

4.2 默认表名字段名

var joinOn = JoinOnQuery.Create("Comments", "Posts")
    .Apply((t1, t2, logic) => logic.And(t1.Field("PostId").Equal(t2.Field("Id"))));
JoinTableQuery query = joinOn.Root
    .Apply("t1", static (c, q) => q.And(c.Field("Pick").EqualValue(true)))
    .Apply("t2", static (p, q) => q.And(p.Field("Author").EqualValue("张三")));

SELECT * FROM [Comments] AS t1 INNER JOIN [Posts] AS t2 ON t1.[PostId]=t2.[Id] WHERE t1.[Pick]=1 AND t2.[Author]='张三'

4.3 使用表名生成别名表

var c = SimpleTable.Use("Comments")
    .As("c");
var p = SimpleTable.Use("Posts")
    .As("p");
var joinOn = JoinOnQuery.Create(c, p)
    .And(c.Field("PostId").Equal(p.Field("Id")));
JoinTableQuery query = joinOn.Root
    .And(c.Field("Pick").EqualValue(true))
    .And(p.Field("Author").EqualValue("张三"));

SELECT * FROM [Comments] AS c INNER JOIN [Posts] AS p ON c.[PostId]=p.[Id] WHERE c.[Pick]=1 AND p.[Author]='张三'

5. 其他相关功能

• 参看逻辑查询简介