如何避免 MySQL 中 where 子句中的語句重復？

Question

有沒有辦法在WHERE子句中使用別名代替單個結果查詢來避免以下查詢中的語句重復？

SELECT * 
FROM (
    SELECT *
    FROM SomeTable T 
    WHERE created <= (CASE WHEN 
        (SELECT created 
        FROM SomeTable 
        WHERE sales > 0 
        ORDER BY created DESC 
        LIMIT 1)
    IS NULL THEN NOW() ELSE 
    (SELECT created 
        FROM SomeTable 
        WHERE sales > 0 
        ORDER BY created DESC 
        LIMIT 1)
    END)
    ORDER BY created DESC LIMIT 10
) as inverseOrder
ORDER BY created ASC;

是否可以修改該查詢以避免語句重復。 即類似的東西？

SELECT * 
FROM (
    SELECT *
    FROM SomeTable T 
    WHERE created <= someAliasssssssss
    IS NULL THEN NOW() ELSE someAliasssssssss
    ORDER BY created DESC LIMIT 10
) as inverseOrder
ORDER BY created ASC;

Answer 1

您可以使用COALESCE() ：

SELECT * 
FROM (
    SELECT *
    FROM SomeTable T 
    WHERE created <= COALESCE(
        (SELECT created 
        FROM SomeTable 
        WHERE sales > 0 
        ORDER BY created DESC 
        LIMIT 1), NOW())
    ORDER BY created DESC LIMIT 10
) as inverseOrder
ORDER BY created ASC;