Question

目前我有三个不同的表和三个不同的查询，它们彼此非常相似，具有几乎相同的连接。我试图在一个查询中将所有三个查询组合在一起，但到目前为止还没有多少成功。如果有人有更好的解决方案或指示方向，我将非常高兴。感谢。

0.0013       
SELECT `ilan_genel`.`id`, `ilan_genel`.`durum`, `ilan_genel`.`kategori`, `ilan_genel`.`tip`, `ilan_genel`.`ozellik`, `ilan_genel`.`m2`, `ilan_genel`.`fiyat`, `ilan_genel`.`baslik`, `ilan_genel`.`ilce`, `ilan_genel`.`mahalle`, `ilan_genel`.`parabirimi`, `kgsim_ilceler`.`isim` as ilce, (
 SELECT ilanresimler.resimlink
 FROM ilanresimler
 WHERE ilanresimler.ilanid = ilan_genel.id LIMIT 1
 ) AS resim
FROM (`ilan_genel`)
LEFT JOIN `kgsim_ilceler` ON `kgsim_ilceler`.`id` = `ilan_genel`.`ilce`
ORDER BY `id` desc
LIMIT 30 
0.0006       
SELECT `video`.`id`, `video`.`url`, `ilan_genel`.`ilce`, `ilan_genel`.`tip`, `ilan_genel`.`m2`, `ilan_genel`.`ozellik`, `ilan_genel`.`fiyat`, `ilan_genel`.`parabirimi`, `ilan_genel`.`kullanici`, `ilanresimler`.`resimlink` as resim, `uyeler`.`isim` as isim, `uyeler`.`soyisim` as soyisim, `kgsim_ilceler`.`isim` as ilce
FROM (`video`)
LEFT JOIN `ilan_genel` ON `ilan_genel`.`id` = `video`.`id`
LEFT JOIN `kgsim_ilceler` ON `kgsim_ilceler`.`id` = `ilan_genel`.`ilce`
LEFT JOIN `ilanresimler` ON `ilanresimler`.`id` = `ilan_genel`.`resim`
LEFT JOIN `uyeler` ON `uyeler`.`id` = `ilan_genel`.`kullanici`
ORDER BY `siralama` desc
LIMIT 30 
0.0005       
SELECT `sanaltur`.`id`, `ilan_genel`.`ilce`, `ilan_genel`.`tip`, `ilan_genel`.`m2`, `ilan_genel`.`ozellik`, `ilan_genel`.`fiyat`, `ilan_genel`.`parabirimi`, `ilan_genel`.`kullanici`, `ilanresimler`.`resimlink` as resim, `uyeler`.`isim` as isim, `uyeler`.`soyisim` as soyisim, `kgsim_ilceler`.`isim` as ilce
FROM (`sanaltur`)
LEFT JOIN `ilan_genel` ON `ilan_genel`.`id` = `sanaltur`.`id`
LEFT JOIN `kgsim_ilceler` ON `kgsim_ilceler`.`id` = `ilan_genel`.`ilce`
LEFT JOIN `ilanresimler` ON `ilanresimler`.`id` = `ilan_genel`.`resim`
LEFT JOIN `uyeler` ON `uyeler`.`id` = `ilan_genel`.`kullanici`
ORDER BY `siralama` desc
LIMIT 30

Answer 1

这些实际上是三个非常不同的查询。我认为你不能有效地将它们结合起来。而且，它们对我来说似乎很快。

但是，如果您想尝试优化每个查询，可以使用EXPLAIN SELECT查看每个查询是否使用适当的索引。

例如：

EXPLAIN SELECT * 
FROM A 
WHERE foo NOT IN (1,4,5,6);

可能产量：

+----+-------------+-------+------+---------------
| id | select_type | table | type | possible_keys 
+----+-------------+-------+------+---------------
|  1 | SIMPLE      | A     | ALL  | NULL          
+----+-------------+-------+------+---------------

+------+---------+------+------+-------------+
| key  | key_len | ref  | rows | Extra       |
+------+---------+------+------+-------------+
| NULL | NULL    | NULL |    2 | Using where |
+------+---------+------+------+-------------+

在这种情况下，查询没有possible_keys，因此使用no（或NULL）key来执行查询。这是您感兴趣的key列。

此处提供更多信息：

有没有更好的方法来做这些mysql查询？

1 个答案: