sql - 具有多个结果集的 TSQL 查询

Question

我有 3 个表，其中 ID 可能在表 1、表 2、表 3 或表 1 和表 3 中。

我需要做的是将 ID 作为参数传递给存储过程，然后检查 3 个表并返回一个结果集，其中 ID 在 3 个表中的 1 个中找到。

在表1和表3中都找到ID的情况下，我需要返回表3的结果集。

所有表不包含相同数量的列。我似乎无法正确构建它。

到目前为止，这是我的存储过程:

ALTER PROCEDURE [dbo].[Login]

@userId varchar(20)

AS
BEGIN
SET NOCOUNT ON;

-- Customer Service User
IF EXISTS
               (
                   SELECT cs.id,
                                 first_name,
                                 last_name,
                                 logins.[email_address],
                                 logins.[password],
                                 phone,
                                 shift,
                                 manager,
                                 location
                   FROM customer_service cs
                   INNER JOIN logins ON cs.id = logins.[id]
                   WHERE cs.id = logins.[id]
                )

-- Marketing User
IF EXISTS
               (
                   SELECT mktg.id,
                                 first_name,
                                 last_name,
                                 logins.[email_address],
                                 logins.[password],
                                 phone,
                                 manager,
                                 location
                   FROM marketing mktg
                   INNER JOIN logins ON mktg.id = logins.[id]
                   WHERE mktg.id = logins.[id]
                )

-- Remote User
IF EXISTS
               (
                   SELECT ru.id,
                                 first_name,
                                 last_name,
                                 logins.[email_address],
                                 logins.[password],                                    
                                 manager,
                                 location
                   FROM remote ru
                   INNER JOIN logins ON ru.id = logins.[id]
                   WHERE ru.id = logins.[id]
                )

Answer 1

无论数据来自哪个表，您都希望存储过程返回相同的列，所以我会 union选择语句一起使用 NULL对于不在给定表中的列名。由于您只想在第三个表中不存在 id 时返回第一个表中的记录，因此我将其添加到第一个选择的 where 中。条款:

ALTER PROCEDURE [dbo].[Login]

@userId varchar(20)
AS BEGIN SET NOCOUNT ON;

-- Customer Service User
SELECT
    cs.id,
    first_name,
    last_name,
    logins.[email_address],
    logins.[password],
    phone,
    shift,
    manager,
    location
FROM customer_service cs
    INNER JOIN logins ON cs.id = logins.[id]
WHERE cs.id = @userId
    and not exists(select 1
                   from remote
                   where id = @userId)
union all
-- Marketing User
SELECT
    mktg.id,
    first_name,
    last_name,
    logins.[email_address],
    logins.[password],
    phone,
    null as shift,
    manager,
    location
FROM marketing mktg
    INNER JOIN logins ON mktg.id = logins.[id]
WHERE mktg.id = @userId
union all
-- Remote User
SELECT
    ru.id,
    first_name,
    last_name,
    logins.[email_address],
    logins.[password],   
    null as phone,
    null as shift,                                 
    manager,
    location
FROM remote ru
INNER JOIN logins ON ru.id = logins.[id]
WHERE ru.id = @userId

end