Question

我在PHP中有以下MySQL查询，它传递一个变量来完成查询：

SELECT * from mobile_tech WHERE uid=$uid  order by timestamp DESC limit 0,1

我有以下MySQL JOIN，它提供来自两个表的数据：

SELECT mobile_tech.latitude, mobile_tech.longitude, mobile_tech.timestamp, mobile_tech.uid, gbl_qemplisting.EmpNo, gbl_qemplisting.FirstName, gbl_qemplisting.LastName 
FROM mobile_tech, gbl_qemplisting
WHERE mobile_tech.uid=gbl_qemplisting.EmpNo AND date(timestamp)='$currentday' 
group by uid

我需要将这两个查询合并为一个JOIN并仍然传递$ uid变量来完成查询。

我尝试过以下操作但没有用：

SELECT mobile_tech.latitude, mobile_tech.longitude, mobile_tech.timestamp, mobile_tech.uid, gbl_qemplisting.EmpNo, gbl_qemplisting.FirstName, gbl_qemplisting.LastName 
FROM mobile_tech, gbl_qemplisting
WHERE mobile_tech.uid=$uid AND gbl_qemplisting.EmpNo=$uid AND date(timestamp)='$currentday'

Answer 1

您的查询将返回mobile_tech行的gbl_emplisting和$uid行之间的叉积。如果您只想要一行，就像在第一个查询中一样，请同样使用ORDER BY和LIMIT。

SELECT mobile_tech.latitude, mobile_tech.longitude, mobile_tech.timestamp, mobile_tech.uid, gbl_qemplisting.EmpNo, gbl_qemplisting.FirstName, gbl_qemplisting.LastName 
FROM mobile_tech, gbl_qemplisting
WHERE mobile_tech.uid=$uid AND gbl_qemplisting.EmpNo=$uid AND date(timestamp)='$currentday'
ORDER BY mobile_tech.timestamp
LIMIT 1

Answer 2

请尝试使用此功能并说出结果

MySQL JOIN将PHP变量传递给两个表

2 个答案: