[英]Join between two tables duplicating some results
我在我的 PHP 中通过这个查询连接了两个表:
SELECT a.id,b.address
FROM mytable a
LEFT JOIN mysecondtable b
ON a.`id`=b.`id`
WHERE a.`Name` LIKE '?'
在表 b 中,我有 2 行具有相同的用户“id”,但带有我想要的查询:对于一个 id 两个地址,结果相同
目前我有 2 个结果如下:
12 theaddress
12 thesecondaddress
我想
12 theaddress thesecondaddress
可能吗?
如果您最多有两个,则可以使用聚合:
SELECT a.id MIN(b.address) as address1,
NULLIF(MAX(b.address), MIN(b.address)) as address2
FROM mytable a LEFT JOIN
mysecondtable b
ON a.`id`=b.`id`
WHERE a.`Name` LIKE ?
GROUP BY a.id;
如果您有不确定数量的地址,您可以将它们放入带有分隔符的字符串中:
SELECT a.id GROUP_CONCAT(b.address SEPARATOR '|') as addresses
FROM mytable a LEFT JOIN
mysecondtable b
ON a.`id`=b.`id`
WHERE a.`Name` LIKE ?
GROUP BY a.id
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