Question

我是一个大多数时候都在使用ORM的SQL新手。我在以下查询中遇到别名问题：

command.CommandText = @"
    INSERT INTO permissions (userid, remoteid)
        SELECT userid as uid, :remoteid as rid
        FROM users
        WHERE companyid = :companyid
            AND NOT EXISTS (
                SELECT 1
                FROM permissions
                WHERE userid = uid
                AND remoteid = rid
            )";

command.Parameters.AddWithValue("companyid", companyId);
command.Parameters.AddWithValue("remoteid", resourceId);

执行查询时，出现以下错误：

ERROR: 42703: column "uid" does not exist

我做错了什么？别名是否应该像这样使用，是否可以在INSERT语句中使用？

Answer 1

怎么样：

command.CommandText = @"
    INSERT INTO permissions (userid, remoteid)
        SELECT userid, :remoteid as rid
        FROM users uid
        WHERE companyid = :companyid
            AND NOT EXISTS (
                SELECT 1
                FROM permissions
                WHERE userid = uid.userid
                AND remoteid = rid
            )";

command.Parameters.AddWithValue("companyid", companyId);
command.Parameters.AddWithValue("remoteid", resourceId);

在insert语句中使用别名

1 个答案: