如何过早地获得游标中的最后一次迭代？

Question

如何提前获取游标中的最后一次迭代以将其与值进行比较并在满足条件时中断。

OPEN lcr_trans   
    FETCH NEXT FROM lcr_trans INTO @trans_time , @machine_id , @trans_camp_code;
    WHILE @@FETCH_STATUS = 0   
    BEGIN
    IF(cast(@shift_start_time as time)<>'00:00:00.0000000'  AND (cast(@shift_end_time as time)<>'00:00:00.0000000' )  )
    BEGIN

      SELECT  TOP 1 @CompareWeekend= transtime_out from overtime where emp_num = @emp_num and trans_date = @previous_date;

      IF(@CompareWeekend  = @trans_time)
        BEGIN
            BREAK;
        END
    END
    -- The Cursor --
    --   ----     --
        FETCH NEXT FROM lcr_trans INTO @trans_time , @machine_id , @trans_camp_code;
    END 
    close lcr_trans;
    DEALLOCATE lcr_trans; 

我希望迭代中的最后一个 @trans_time 与我的变量 .@CompareWeekend 进行比较

Answer 1

试试这个：

declare @last_trans_time datetime, @last_machine_i varchar(max), @last_trans_camp_code varchar(max);
    OPEN lcr_trans   
        FETCH LAST FROM lcr_trans INTO @last_trans_time , @last_machine_i , @last_trans_camp_code;

        FETCH NEXT FROM lcr_trans INTO @trans_time , @machine_id , @trans_camp_code;
        WHILE @@FETCH_STATUS = 0   
        BEGIN
           IF(cast(@shift_start_time as time)<>'00:00:00.0000000'  AND (cast(@shift_end_time as time)<>'00:00:00.0000000' )  )
           BEGIN

             SELECT  TOP 1 @CompareWeekend= transtime_out from overtime where emp_num = @emp_num and trans_date = @previous_date;

             IF(@CompareWeekend  = @trans_time)
             BEGIN
               BREAK;
             END
           END
           FETCH NEXT FROM lcr_trans INTO @trans_time , @machine_id , @trans_camp_code;
        END 
   CLOSE lcr_trans;
   DEALLOCATE lcr_trans; 

您可以在此处阅读有关游标的更多信息： https://msdn.microsoft.com/en-us/library/ms180152.aspx

Answer 2

您可以使用LAST 关键字（source）获取游标中的最后一行：

FETCH LAST FROM lcr_trans INTO @trans_time , @machine_i , @trans_camp_code;