使用'if'，'else'选择所需的列并进行比较

Question

我试图选择这样：

SELECT *, (SELECT IF(type=1, price_1, price_2)) as price_column WHERE price_column > 10

但是得到了这个错误：

Unknown column 'price_column' in where clause

任何提示？

Answer 1

这样做不简单吗？

SELECT *, IF ( id = 1, field1,field2) AS new_field
FROM table_a
having new_field > 10;

Answer 2

您可以使用

SELECT * 
FROM (
     SELECT *, (SELECT IF(type=1, price_1, price_2)) as price_column
     ) AS Tab1
WHERE price_column > 10

Answer 3

首先你从表中遗漏了，你可以使用它：

SELECT *, (SELECT IF(type=1, price_1, price_2)) as price_column 
from table_name WHERE (SELECT IF(type=1, price_1, price_2)) > 10