Question

如果m.message_type_id IN（）为空，则会给我一个错误，上面写着

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') ) UNION ( ' at line 16

        SELECT m.id,m.log,message,images,videos,uo.user_id as to_id,owner_id,
        IF(m.owner_id = 45,'sent','received') as type
        FROM messages as m 
        LEFT JOIN events as e ON m.message_type_id = e.id
        LEFT JOIN user_organization as uo ON uo.id = e.org_id
        WHERE m.message_type_id IN ()
        AND m.type = 'event_invite_request_msg'

如果WHERE m.message_type_id IN（61）它给了我正确的答案。

解决方案是什么？

Answer 1

IN Clause希望你发送至少一个值，为什么你认为即使使用空参数也应该有效？

expr NOT IN（value，...）

<强> Syntax

在更广泛的层面上，几乎所有的比较都是这种情况，如果存在无效的值来比较，为什么你会期望比较不会导致错误

这对你有用吗？

SELECT myField FROM myTable WHERE MyField2 =

不，它不会

Answer 2

您必须为此使用条件

if(count($friendsArray[])){
        $qry = "SELECT m.id,m.log,message,images,videos,uo.user_id as to_id,owner_id,
        IF(m.owner_id = 45,'sent','received') as type
        FROM messages as m 
        LEFT JOIN events as e ON m.message_type_id = e.id
        LEFT JOIN user_organization as uo ON uo.id = e.org_id
        WHERE m.message_type_id IN ($ids)
        AND m.type = 'event_invite_request_msg'";
}else{
        $qry = "SELECT m.id,m.log,message,images,videos,uo.user_id as to_id,owner_id,
        IF(m.owner_id = 45,'sent','received') as type
        FROM messages as m 
        LEFT JOIN events as e ON m.message_type_id = e.id
        LEFT JOIN user_organization as uo ON uo.id = e.org_id
        WHERE m.type = 'event_invite_request_msg'";
}

如果NOT IN内的值为空，则mysql会抛出错误

2 个答案: