mysql更改日期格式 [英] mysql change date format

问题描述

我有一个日期字段(tinytext)，其中保存着日期信息，格式为"dd-mm-yy"，例如07-01-90.使用mysql查询，我想将其更改为yyyy-mm-dd日期格式.我尝试了下面的代码，但没有任何反应.

I have a date field (tinytext) holding date information in format of "dd-mm-yy" e.g 07-01-90. Using a mysql query I want to change it to yyyy-mm-dd date format. I tried the code below but nothing happens.

mysql_query("UPDATE Table SET date=STR_TO_DATE('date','%Y,%m,%d')");

推荐答案

您正在使用正确的函数STR_TO_DATE(str,format)来实现目标，但您犯了两个错误:

You're using the correct function STR_TO_DATE(str,format) to achieve the goal, but you're making two mistakes:

1. 查询中的 format 参数与字符串表达式格式不匹配.当您将%Y,%m,%d(逗号分隔)传递给 format 参数时，您说它是dd-mm-yy格式.该查询将返回日期时间值错误"错误.您应该使用%d-%m-%Y.
2. 您不能通过设置要传递的值的其他类型来即时更改列的数据类型.您必须先更新值，然后更改列的数据类型.

1. In your query the format argument does not match the string expression format. You said it's in dd-mm-yy format while you passed %Y,%m,%d (comma separated) to the format argument. The query will return a "incorrect datetime value" error. You should use %d-%m-%Y.
2. You can't change data type of a column on the fly, by setting different type of the value being passed. You have to first update the values and then change data type for column.

所以，总结一下:

mysql_query("UPDATE `Table` SET `date` = STR_TO_DATE(`date`, '%d-%m-%Y')");
mysql_query("ALTER TABLE `Table` CHANGE COLUMN `date` `date` DATE");

另外，请考虑切换到建议的 PDO 扩展名，代替原来的已弃用 mysql扩展名.

Additionally, consider switching to the recommended PDO extension in place of old and slowly deprecated mysql extension.

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