What is the method for performing multi-table joins in linq?

To perform a multiple table join query in LINQ, use the “join” keyword to connect multiple tables and associate them based on specified conditions.

Here is an example code demonstrating how to perform a multi-table join query in LINQ.

var query = from t1 in table1
            join t2 in table2 on t1.Id equals t2.Id
            join t3 in table3 on t2.Id equals t3.Id
            select new { T1 = t1, T2 = t2, T3 = t3 };

foreach (var result in query)
{
    // 处理查询结果
    var t1Data = result.T1;
    var t2Data = result.T2;
    var t3Data = result.T3;
}

In the example above, suppose there are three tables: table1, table2, and table3, which are linked by the Id field. The tables are connected using the “join” keyword, with the association conditions specified using the “equals” keyword. Finally, the desired fields or entire tables are selected using the “select” keyword.

It is important to ensure that the fields being connected in a multi-table join query have the same type and name in order to correctly establish the relationship.