mysql - mysql how to change integer values in column from format of 20130401 to 0401

Question

I would like to update the whole column from the format of yearmonthday to just monthday

for example a value in this column is 20130401 and I want to change it to 0401

Answer 1

如果您的列是 varchar 列，则可以使用如下内容：

UPDATE yourtable
SET
  col = DATE_FORMAT(STR_TO_DATE(col, "%Y%m%d"), "%m%d")

或者也许只是：

UPDATE yourtable
SET col = RIGHT(col, 4)

编辑

如果您需要先创建一个新列然后删除旧列，您可以使用这个：

ALTER TABLE yourtable ADD COLUMN col2 VARCHAR(20);

UPDATE yourtable
SET col2 = RIGHT(col, 4);

ALTER TABLE yourtable DROP COLUMN col;

请在此处查看小提琴。