c# linq ef 多表查询写法

在C#中使用LINQ和Entity Framework进行多表查询的写法可以有多种方式，以下是一些常见的示例：

1. 基本查询：

var query = from t1 in dbContext.Table1
            join t2 in dbContext.Table2 on t1.Id equals t2.Table1Id
            select new { t1, t2 };

2. 过滤条件查询：

var query = from t1 in dbContext.Table1
            join t2 in dbContext.Table2 on t1.Id equals t2.Table1Id
            where t1.Name == "someName" && t2.IsActive
            select new { t1, t2 };

3. 多个连接查询：

var query = from t1 in dbContext.Table1
            join t2 in dbContext.Table2 on t1.Id equals t2.Table1Id
            join t3 in dbContext.Table3 on new { t1.Id, t2.Id } equals new { t3.Table1Id, t3.Table2Id }
            select new { t1, t2, t3 };

4. 左连接查询：

var query = from t1 in dbContext.Table1
            join t2 in dbContext.Table2 on t1.Id equals t2.Table1Id into joinedTable
            from subTable in joinedTable.DefaultIfEmpty()
            select new { t1, subTable };

以上只是一些常见的多表查询写法示例，实际应用中可以根据具体需求进行灵活组合和扩展。