在 SQL Server 2008 中执行 while 循环

SQL server 2008有没有实现do while循环的方法?

解决方案

我不确定 MS SQL Server 2008 中的 DO-WHILE,但您可以更改 WHILE 循环逻辑,以便像 DO-WHILE 循环一样使用.

示例取自此处:http://blog.sqlauthority.com/2007/10/24/sql-server-simple-example-of-while-loop-with-continue-and-break-keywords/

<块引用>

  1. WHILE 循环示例

    DECLARE @intFlag INT设置@intFlag = 1同时 (@intFlag <=5)开始打印@intFlagSET @intFlag = @intFlag + 1结尾走

    结果集:

    12345

  2. 带有 BREAK 关键字的 WHILE 循环示例

    DECLARE @intFlag INT设置@intFlag = 1同时 (@intFlag <=5)开始打印@intFlagSET @intFlag = @intFlag + 1如果@intFlag = 4休息;结尾走

    结果集:

    123

  3. 带有 CONTINUE 和 BREAK 关键字的 WHILE 循环示例

    DECLARE @intFlag INT设置@intFlag = 1同时 (@intFlag <=5)开始打印@intFlagSET @intFlag = @intFlag + 1继续;IF @intFlag = 4 -- 这将永远不会执行休息;结尾走

    结果集:

    12345

但是尽量在数据库级别避免循环.参考.

Is there any method for implement do while loop in SQL server 2008?

解决方案

I am not sure about DO-WHILE IN MS SQL Server 2008 but you can change your WHILE loop logic, so as to USE like DO-WHILE loop.

Examples are taken from here: http://blog.sqlauthority.com/2007/10/24/sql-server-simple-example-of-while-loop-with-continue-and-break-keywords/

  1. Example of WHILE Loop

    DECLARE @intFlag INT
    SET @intFlag = 1
    WHILE (@intFlag <=5)
    BEGIN
        PRINT @intFlag
        SET @intFlag = @intFlag + 1
    END
    GO
    

    ResultSet:

    1
    2
    3
    4
    5
    

  2. Example of WHILE Loop with BREAK keyword

    DECLARE @intFlag INT
    SET @intFlag = 1
    WHILE (@intFlag <=5)
    BEGIN
        PRINT @intFlag
        SET @intFlag = @intFlag + 1
        IF @intFlag = 4
            BREAK;
    END
    GO
    

    ResultSet:

    1
    2
    3
    

  3. Example of WHILE Loop with CONTINUE and BREAK keywords

    DECLARE @intFlag INT
    SET @intFlag = 1
    WHILE (@intFlag <=5)
    BEGIN
        PRINT @intFlag
        SET @intFlag = @intFlag + 1
        CONTINUE;
        IF @intFlag = 4 -- This will never executed
            BREAK;
    END
    GO
    

    ResultSet:

    1
    2
    3
    4
    5
    

But try to avoid loops at database level. Reference.

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