Question

以下SQL语句的对应linq2sql-Statement是什么？

SELECT id, userName
FROM users
WHERE
  (SELECT COUNT(*) FROM logins WHERE logins.userId=users.id) > 0

或写为联接：

SELECT id, userName
FROM users 
LEFT JOIN logins ON logins.id=(SELECT MIN(id) FROM logins WHERE userId=users.id)
WHERE logins.id IS NOT NULL

THX

Answer 1

假设您的上下文中有“user”和“login”DBSet，并且您的上下文的名称是“context”：

var result = from user in context.users
             where (from  login in context.logins
                     where login.userId = user.userId
                     select login).Count() > 0
             select user.Id,userName

Linq2sql for Where-Clause或join中的Aggregate-Function

1 个答案: