SQL Server 2008 R2 存储过程中带有子 IF 语句的 WHILE 条件？

Question

我在 SQL Server 2008 R2 的存储过程中得到了以下代码。

..
@currentAccID     char(21), 
@currentUserID    char(21),
@UserID1    char(21),
@UserID2    char(21),
@UserID3    char(21),
@Case     smallint, 

...
SELECT @UserID1 = UserID1, @UserID2 = UserID2, @UserID3 = UserID3 FROM OLD_Users WHERE oldAccID = @currentAccID

WHILE (@userid1 = @userid or @userid2 = @userid or @userid3 = @userid)
BEGIN
    IF (@Case = 10 OR @Case = 20) 
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_NormalUser'
    END
    ELSE IF (@Case = 12 OR @Case = 22)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_MediumUser'
    END
    ELSE IF (@Case = 13 OR @Case = 23)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_HighUser'
    END
    ELSE IF (@Case = 14 OR @Case = 24)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_UltraUser'
    END
END

WHILE (@userid1 != @userid or @userid2 != @userid or @userid3 != @userid)
BEGIN
    IF (@Case = 10 OR @Case = 20) 
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'NormalUser'
    END
    ELSE IF (@Case = 12 OR @Case = 22)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'MediumUser'
    END
    ELSE IF (@Case = 13 OR @Case = 23)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'HighUser'
    END
    ELSE IF (@Case = 14 OR @Case = 24)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'UltraUser'
    END
END

...
INSERT INTO NewUser (UserID,Case,Equipment ......) VALUES (@UserID,@Case,@Equipment .......)

以上代码是否正确？此外，还有第三种可能性，其中 @currentAccID 与 OLD_Users table 中的 oldAccID 与 SELECT 查询完全不匹配，但它应该没问题因为第二个 WHILE 语句将被执行，对吗？性能不应该有问题吗？我很确定使用 WHILE 语句等可以做得更好，但我不擅长 SQL 存储过程。预先感谢您花时间帮助我！

Answer 1

那么你不应该使用 while 循环。它可以通过简单的 if-else 语句来实现。请使用以下代码执行相同的操作：

..
@currentAccID     char(21), 
@currentUserID    char(21),
@UserID1    char(21),
@UserID2    char(21),
@UserID3    char(21),
@Case     smallint, 

...
-- this condition checks whether @userid is present in any of the columns UseID1 or UserID2 or UserID3
IF EXISTS(SELECT NULL FROM OLD_Users WHERE oldAccID = @currentAccID AND (UserID1 = @userid OR UserID2 = @userid OR UserID3 = @userid))
BEGIN
    SET  @OldORNew = 1
    IF (@Case = 10 OR @Case = 20) 
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_NormalUser'
    END
    ELSE IF (@Case = 12 OR @Case = 22)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_MediumUser'
    END
    ELSE IF (@Case = 13 OR @Case = 23)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_HighUser'
    END
    ELSE IF (@Case = 14 OR @Case = 24)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'OLD_UltraUser'
    END
END
ELSE
BEGIN
    SET  @OldORNew = 0
    IF (@Case = 10 OR @Case = 20) 
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'NormalUser'
    END
    ELSE IF (@Case = 12 OR @Case = 22)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'MediumUser'
    END
    ELSE IF (@Case = 13 OR @Case = 23)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'HighUser'
    END
    ELSE IF (@Case = 14 OR @Case = 24)
    BEGIN
        SELECT TOP 1 @Equipment = Equipment FROM Users WHERE UserID = 'UltraUser'
    END
END

...
INSERT INTO NewUser (UserID,Case,Equipment ......) VALUES (@UserID,@Case,@Equipment .......)

SQL Server 2008 R2 存储过程中带有子 IF 语句的 WHILE 条件？

WHILE condition with sub IF statements in SQL Server 2008 R2 stored procedure?

sql-server

stored-procedures

sql-server-2008-r2