条款左边加入MySQL

Question

大家好，我可以问一下我在哪里可以将where子句放在查询

的左连接中

SELECT en.`transid`, en.`transdate`, 
                CONCAT(userlist.lname, ', ', userlist.fname, ' ', userlist.mname) AS sender_name, 
                CONCAT(userlist1.lname, ', ', userlist1.`fname`, ' ', userlist1.`mname`) AS receiver_name,
                en.`document_num`, doctype.`document_type`, vendor.`vendor_name`, acknowledge.`status`
                FROM `tbl_encode_transmittal` en 
                LEFT JOIN `tbl_acknowledgetransmittal` acknowledge ON en.`transid` = acknowledge.`transid`
                LEFT JOIN tbl_userlist userlist ON userlist.userid = en.sender_id
                LEFT JOIN tbl_userlist userlist1 ON userlist1.userid = en.`receiver_id`
                LEFT JOIN `tbl_doctype` doctype ON doctype.`doc_id` = en.`doctype_id`
                LEFT JOIN tbl_vendor vendor ON vendor.`vendor_id` =  en.vendor_id

这是我将在查询中包含的Where子句：

WHERE userlist1.userid = 'admin'

Answer 1

你可以像其他人说的那样把它放在最后，或像这样的“AND”：

SELECT en.`transid`, en.`transdate`, 
                CONCAT(userlist.lname, ', ', userlist.fname, ' ', userlist.mname) AS sender_name, 
                CONCAT(userlist1.lname, ', ', userlist1.`fname`, ' ', userlist1.`mname`) AS receiver_name,
                en.`document_num`, doctype.`document_type`, vendor.`vendor_name`, acknowledge.`status`
                FROM `tbl_encode_transmittal` en 
                LEFT JOIN `tbl_acknowledgetransmittal` acknowledge ON en.`transid` = acknowledge.`transid`
                LEFT JOIN tbl_userlist userlist ON userlist.userid = en.sender_id
                LEFT JOIN tbl_userlist userlist1 ON userlist1.userid = en.`receiver_id` AND userlist1.userid = 'admin'
                LEFT JOIN `tbl_doctype` doctype ON doctype.`doc_id` = en.`doctype_id`
                LEFT JOIN tbl_vendor vendor ON vendor.`vendor_id` =  en.vendor_id

Answer 2

使用什么连接类型无关紧要，where子句遵循from子句和连接条件：

FROM `tbl_encode_transmittal` en 
                LEFT JOIN `tbl_acknowledgetransmittal` acknowledge ON en.`transid` = acknowledge.`transid`
                LEFT JOIN tbl_userlist userlist ON userlist.userid = en.sender_id
                LEFT JOIN tbl_userlist userlist1 ON userlist1.userid = en.`receiver_id`
                LEFT JOIN `tbl_doctype` doctype ON doctype.`doc_id` = en.`doctype_id`
                LEFT JOIN tbl_vendor 4vendor ON vendor.`vendor_id` =  en.vendor_id
WHERE userlist1.userid = 'admin'

Answer 3

您将它们放在FROM和JOIN条款之后，就像正常一样。

SELECT *
FROM table1 t1
JOIN table t2 ON t1.id = t2.fk
WHERE t1.whatever = "whatever"