插入条件查询

Question

我正在尝试创建一个SQL查询，其中我需要检查来自2个表的列的总和，然后在满足条件时将新行插入另一个表中。我知道我可以使用带有显式锁定的存储过程，但想知道是否可以在单个SQL查询中执行此操作。我写了以下内容，但它在MySQL工作台中提供了语法错误

INSERT INTO table1 (`col1`, `col2`) 
VALUES ('abc', 'xyz') WHERE 
(
((select 
COUNT(*) from table2 t2 where t2.id = 1)
+ (select sum(t3.counter) from table3 t3 
WHERE t3.id = 1)) < (select t4.total_allowed 
FROM table4 t4 where t4.id = 1)
);

Answer 1

这可以做到，因为你可以insert the results of a select query。

INSERT INTO table1 (`col1`, `col2`) 
SELECT 'abc', 'xyz'
FROM DUAL WHERE 
(
((select 
COUNT(*) from table2 t2 where t2.id = 1)
+ (select sum(t3.counter) from table3 t3 
WHERE t3.id = 1)) < (select t4.total_allowed 
FROM table4 t4 where t4.id = 1)
);

Answer 2

MySQL INSERT语法不支持WHERE子句。