我试图只从表代理中选择数据，该代理在佣金表中与某个承运人有条目。我的 SQL 查询返回所有条目 3 次。我做错了什么。
$allquery = mysql_query("SELECT agency.ID, agency.agencyname, agency.contdate, agency.physcity FROM agency LEFT JOIN commission ON commission.repnum = agency.repid WHERE agency.repid = '$repid' AND commission.repnum = '$repid' AND commission.carrier = 'Carrier' ")or die(mysql_error())
最佳答案
除非您实际指定涉及每个表中的列的连接条件，否则您不会连接两个表。
SELECT agency.ID, agency.agencyname, agency.contdate, agency.physcity
FROM agency LEFT JOIN commission ON commision.repid = agency.repid AND commission.carrier = 'Carrier'
关于MySQL 左连接不工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9146862/