[英]MYSQL LEFT JOIN + WHERE clause return rows with NULL result
I have a query in MYSQL 我在MYSQL中有一个查询
SELECT grand.user_id,grand.package_id,MAX(grand.grand_level) AS level,pam.original_title,um.name
FROM grand_score_master AS grand
LEFT JOIN package_master AS pam ON pam.id = grand.package_id
LEFT JOIN user_master AS um ON um.id = grand.user_id
WHERE grand.package_id='d47kndffqc' AND grand.user_id='CBS_00001'
So if the WHERE clause is matched the result is as expected. 因此,如果WHERE子句匹配,则结果符合预期。
But when the WHERE clause is not matched I expect 0 results
but mysql gives me 但是当WHERE子句不匹配时,我期待0 results
但是mysql给了我
How can I have "0 results" in LEFT JOIN / INNER JOIN. 如何在LEFT JOIN / INNER JOIN中获得“0结果”。
I will use this query in PHP for AJAX requests. 我将在PHP中使用此查询来获取AJAX请求。
Try using ISNULL method for sql amd IFNULL for MySQL. 尝试使用ISNULL方法为sql amd IFNULL for MySQL。
Eg ISNULL(grand.user_id,0)
, IFNULL (grand.user_id,0)
例如ISNULL(grand.user_id,0)
, IFNULL (grand.user_id,0)
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.