MySQL JOIN將PHP變量傳遞給兩個表

Question

我在PHP中有以下MySQL查詢，該查詢傳遞變量以完成查詢：

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

我有以下MySQL JOIN，它提供來自兩個表的數據：

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

我需要將這兩個查詢與一個JOIN合並為一個，並仍然傳遞$ uid變量來完成查詢。

我已經嘗試了以下方法，但沒有效果：

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

您的查詢將返回之間的交叉產品mobile_tech和gbl_emplisting行為$uid 。 如果只需要一行，如在第一個查詢中一樣，則類似地使用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

請嘗試這個並說出結果

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 inner join gbl_qemplisting
        on mobile_tech.uid=gbl_qemplisting.EmpNo 
where mobile_tech.uid=$uid AND date(timestamp)='$currentday'