FreeSql （十七）聯表查詢

時間 2019-11-05

標籤 freesql 十七查詢简体版

原文原文鏈接

FreeSql在查詢數據下足了功能，鏈式查詢語法、多表查詢、表達式函數支持得很是到位。html

IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .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")
    .Build();

[Table(Name = "tb_topic")]
class Topic {
    [Column(IsIdentity = true, IsPrimary = true)]
    public int Id { get; set; }
    public int Clicks { get; set; }
    public int TestTypeInfoGuid { get; set; }
    public TestTypeInfo Type { get; set; }
    public string Title { get; set; }
    public DateTime CreateTime { get; set; }
}
class TestTypeInfo {
    public int Guid { get; set; }
    public int ParentId { get; set; }
    public TestTypeParentInfo Parent { get; set; }
    public string Name { get; set; }
    public List<Topic> Topics { get; set; }
}
class TestTypeParentInfo {
    public int Id { get; set; }
    public string Name { get; set; }
}

ISelect<Topic> select => fsql.Select<Topic>();

利用導航屬性聯表

sql = select.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid).ToSql();
//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`

sql = select
    .LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid)
    .LeftJoin(a => a.Type.Parent.Id == a.Type.ParentId).ToSql();
//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`

沒有導航屬性聯表

sql = select.LeftJoin<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid).ToSql();
//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`

sql = select
    .LeftJoin<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid)
    .LeftJoin<TestTypeParentInfo>((a, c) => c.Id == a.Type.ParentId).ToSql();
//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`

聯表任意查

sql = select.From<TestTypeInfo, TestTypeParentInfo>((s, b, c) => s
    .LeftJoin(a => a.TestTypeInfoGuid == b.Guid)
    .LeftJoin(a => b.ParentId == c.Id)).ToSql();
//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`

或者：sql

sql = fsql.Select<Topic, TestTypeInfo, TestTypeParentInfo>()
    .LeftJoin((a, b, c) => a.TestTypeInfoGuid == b.Guid)
    .LeftJoin((a, b, c) => b.ParentId == c.Id).ToSql();
//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`

原生SQL聯表

sql = select.LeftJoin("TestTypeInfo b on b.Guid = a.TestTypeInfoGuid and b.Name = ?bname", new { bname = "xxx" }).ToSql();
//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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