MySQL：字符串中的數字、英文字符、漢字提取 mysql將null和空字符串轉爲0

https://blog.csdn.net/oyezhou/article/details/81665643

mysql將null和空字符串轉爲0

方法一：
select IF(ISNULL(columnName) OR columnName=’’,0,columnName) from tableName;

方法二:
select case when ISNULL(columnName) OR columnName=’’ then 0 else columnName end from tableName;