Question

我正在编写一个存储过程来查看两个表PersonTbl，UserTbl。首先在PersonTbl中搜索userID，如果userID在那里，则从UserTbl获取一个电子邮件地址并返回两者。但是，如果ID不存在，则搜索其他两个表（PersonsPendingTbl，UsersPendingTbl）以获取ID和电子邮件。如果再次找不到ID，则返回null / nulls。到目前为止，这是我提出的，但不确定它是否是编写它的最佳方式。如果您有任何改变，请告诉我们;

create PROCEDURE [dbo].[MyNewSP]
@ID VARCHAR(MAX)
AS 
    DECLARE @userID VARCHAR(50)
    DECLARE @Email VARCHAR(100)
    DECLARE @currentlyActive CHAR
    BEGIN

    SELECT
        @userID = userTbl.ID ,
        @Email = personTbl.EMAIL,
        @currentlyActive = 'Y'
    FROM
        personTbl
        INNER JOIN userTbl ON personTbl.person_id = userTbl.person_id
    WHERE
        ( userTbl.ID = @ID )


    IF ( @userID != @ID ) --Check to see if null
        BEGIN
            SELECT @currentlyActive = 'N'

            SELECT
                upt.ID ,
                ppt.EMAIL,
                @currentlyActive
            FROM
                PersonsPendingTbl ppt
                INNER JOIN dbo.UsersPendingTbl upt ON ppt.person_id = upt.person_id
            WHERE
                ( upt.ID = @ID )
        END
    ELSE 
        BEGIN
            SELECT
                @userID ,
                @Email ,
                @currentlyActive
        END

END

Answer 1

我不确定您的待处理表和非待处理表之间的值的唯一性，但这应该足够接近让您前进。

select 
case 
    when p.PersonId is null and pp.personPendingId is null then null 
    else userid
end as userid,
case 
    when p.PersonId is not null  then p.email
    when p.PersonId is null and pp.PersonPendingID is not null then pp.email
    else null
end as email,
case 
    when p.PersonId is not null  then 'Y' 
    when p.PersonId is null and pp.PersonPendingID is not null then 'N' 
    else null
end as CurrentlyActive
from userTbl u 
left join PersonTbl p on u.Person_id = p.PersonId 
left join userPendingTbl up on u.UserId = up.UserPendingId 
left join PersonPendingTbl pp on up.personPendingId = pp.PersonPendingID 
where u.UserId = @ID

Answer 2

结合两个结果，但总是选择第一行。如果用户注册为“活动和非活动”，它将返回“活动”：

Select * 
  from (
    SELECT userTbl.ID AS UID, personTbl.EMAIL as email, 'Y' as active
      FROM personTbl
        JOIN userTbl ON personTbl.person_id = userTbl.person_id
        WHERE (userTbl.ID = @ID)
    union all
    SELECT upt.ID AS UID, ppt.EMAIL as email, 'N' as active
      FROM PersonsPendingTbl ppt
        INNER JOIN dbo.UsersPendingTbl upt ON ppt.person_id = upt.person_id
      WHERE (upt.ID = @ID)) user
  limit 0,1

如果第一个结果为空，则查询不同的表

2 个答案: