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[ASP.net教程]Linq和EF 做 单一条件查询 和 复合条件 查询 以及 多表 联合查询 示例

单一条件查询:

var table2Object = (from t1 in db.table1       join t2 in db.table2 on t1.id equals t2.id           select t2).FirstOrDefault();

 

复合条件 查询:

多个主键 联合查询

var table2Object = (from t1 in db.table1       join t2 in db.table2       on new { t1.id, t1.another_id } equals new { t2.id, t2.another_id }       select t2).FirstOrDefault();

多表联合查询:

Join3个Table

var table2Object = (from t1 in db.table1       join t2 in db.table2       on new { t1.id, t1.another_id } equals new { t2.id, t2.another_id }       join t3 in db.table3       on new { t2.id, t2.another_id } equals new { t3.id, t3.another_id }       select t2).FirstOrDefault();