DECLARE @nmSupport NUMERIC(14,4),@nmOutst NUMERIC(14,4),@chPart VARCHAR(16) SELECT @chPart = 'XXX' SELECT @nmOutst = 0 SELECT @nmSupport = 0 UPDATE acdb.PAC06.AC06004A SET nmSupport = CASE WHEN chPart = @chPart THEN CASE WHEN nmQty > @nmOutst THEN @nmOutst ELSE nmQty END ELSE CASE WHEN nmQty > nmOutst THEN nmOutst ELSE nmQty END END, nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-nmSupport END, @nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-nmSupport END, @nmSupport = case when chPart = @chPart then case when nmQty > @nmOutst then @nmOutst else nmQty end ELSE CASE WHEN nmQty > nmOutst THEN nmOutst ELSE nmQty END end, @chPart = chPart

这段代码是一个 SQL Server 的存储过程或者脚本，其中包含了一些变量的定义和赋值。具体来说，这段代码的作用是：

1. 声明了三个变量 @nmSupport、@nmOutst 和 @chPart，分别是数值类型和字符类型；
2. 把 @chPart 变量的值设为 'XXX'；
3. 把 @nmOutst 变量的值设为 0；
4. 把 @nmSupport 变量的值设为 0；
5. 更新了 acdb.PAC06.AC06004A 表中的 nmSupport 和 nmOutst 字段，具体更新方式如下：
- 如果 chPart 字段等于 @chPart 变量的值，则 nmSupport 字段的值为 @nmOutst 和 nmQty 两者中较小的一个，nmOutst 字段的值为 @nmOutst 和 @nmSupport 的差值（如果 @nmOutst 大于等于 @nmSupport），或者为 0（如果 @nmOutst 小于 @nmSupport）；
- 如果 chPart 字段不等于 @chPart 变量的值，则 nmSupport 字段的值为 nmQty 和 nmOutst 两者中较小的一个，nmOutst 字段的值为 nmOutst 和 nmSupport 的差值；
6. 最后，更新了 @nmOutst、@nmSupport 和 @chPart 变量的值，使其与更新后的表中的对应字段值相同或者符合上述条件。

相关问题

DECLARE @nmSupport NUMERIC(14,4),@nmOutst NUMERIC(14,4),@chPart VARCHAR(16) SELECT @chPart = 'XXX' SELECT @nmOutst = 0 SELECT @nmSupport = 0 UPDATE acdb.PAC06.AC06004A SET nmSupport = CASE WHEN chPart = @chPart THEN CASE WHEN nmQty > @nmOutst THEN @nmOutst ELSE nmQty END ELSE CASE WHEN nmQty > nmOutst THEN nmOutst ELSE nmQty END END, nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-nmSupport END, @nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-nmSupport END, @nmSupport = case when chPart = @chPart then case when nmQty > @nmOutst then @nmOutst else nmQty end ELSE CASE WHEN nmQty > nmOutst THEN nmOutst ELSE nmQty END end, @chPart = chPart改成用SQLSERVE遍历的方式

可以使用 WHILE 循环遍历实现相同的功能，以下是使用 WHILE 循环的代码示例：

DECLARE @nmSupport NUMERIC(14,4),@nmOutst NUMERIC(14,4),@chPart VARCHAR(16)
DECLARE @rowcount INT, @counter INT
SELECT @counter = 1

SELECT @rowcount = COUNT(*) FROM acdb.PAC06.AC06004A

WHILE @counter <= @rowcount
BEGIN
    SELECT @chPart = chPart, @nmQty = nmQty, @nmOutst = nmOutst, @nmSupport = nmSupport
    FROM (SELECT ROW_NUMBER() OVER (ORDER BY chPart) AS RowNum, chPart, nmQty, nmOutst, nmSupport FROM acdb.PAC06.AC06004A) AS RowConstrainedResult
    WHERE RowNum = @counter

    IF @chPart = 'XXX'
    BEGIN
        SET @nmSupport = CASE WHEN @nmQty > @nmOutst THEN @nmOutst ELSE @nmQty END
    END
    ELSE
    BEGIN
        SET @nmSupport = CASE WHEN @nmQty > @nmOutst THEN @nmOutst ELSE @nmQty END
    END

    UPDATE acdb.PAC06.AC06004A
    SET nmSupport = @nmSupport,
        nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-@nmSupport END,
        @nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-@nmSupport END
    WHERE chPart = @chPart

    SET @counter = @counter + 1
END

请注意，使用 WHILE 循环遍历时，需要先获取表中的行数，如果行数很大，可能会对性能产生影响。

create trigger tr_insert on takes for insert as declare @sno varchar(5) declare @cno varchar(5) declare @credit numeric(3,0) select @sno=ID,@cno=course_id from inserted select @credit=credits from course where course_id=@cno update student set tot_cred=tot_cred+@credit where ID=@sno go

这是一个 SQL Server 数据库中的触发器，用于在 takes 表中插入数据时，更新 student 表中的 tot_cred 字段。具体来说，当在 takes 表中插入一条数据时，触发器会从 inserted 表中获取学生的 ID 和课程的 course_id，并从 course 表中获取该课程的学分 credits。然后，触发器会根据学生的 ID 和课程的学分更新 student 表中的 tot_cred 字段，以反映该学生现在已获得的总学分数。当所有更新完成后，触发器会结束执行。