在mysql的存储过程中执行:insert into table1select*from table2where ...的结果有时候是空的这时插入table1,就会出现Column 'ID' cannot be null的错误请问有什么更加安全做法,如果查询的结果是空就不执行插入,MySQL有提供相关的支持么?
题目链接:点击打开链接题目大意:略。解题思路:略。AC 代码SELECT query_name,ROUND(AVG(rating/position),2)quality,ROUND(COUNT(IF(rating,1,null))/COUNT(*)*100,2)poor_query_percentage FROM Queries GROUP BY query_name