Question

我正在寻找一个想要更新我的表列的想法：当计数前5行然后列='class'而下一行将是'Exam'然后再次在这6行之后它会相同的5和下一个1直到最后。

Sample data:
2016-01-18  Class
2016-01-19  Class
2016-01-20  Class
2016-01-21  Class
2016-01-23  Class
2016-01-24  Exam
2016-01-25  Class
2016-01-26  Class
2016-01-27  Class
2016-01-28  Class
2016-01-30  Class
2016-01-31  Exam
2016-02-01  Class
2016-02-02  Class
2016-02-03  Class
2016-02-04  Class
2016-02-06  Class
2016-02-07  Exam

Answer 1

您可以使用此代码：

UPDATE test t
INNER JOIN (SELECT sdate, @row :=@row +1 AS row,mod(@row,6) AS num
        FROM test, (SELECT @row := 0) r) AS tt
    ON t.sdate = tt.sdate
  SET t.name =
        CASE num 
            WHEN 0 THEN 'Exam'
            ELSE 'Class'
        END;

如果还有其他字段day_off，我们需要仅针对day_off =''的字段进行此更新：

UPDATE test2 t
INNER JOIN (SELECT sdate, @row :=@row +1 AS row,mod(@row,6) AS num
        FROM test2, (SELECT @row := 0) r 
  WHERE day_Off = '') AS tt
    ON t.sdate = tt.sdate
  SET t.name =
        CASE num 
            WHEN 0 THEN 'Exam'
            ELSE 'Class'
        END;

如何按行计数顺序更新表字段

1 个答案: