mysql - MySql 在三个表中的任何一个中查找匹配项？

Question

我试图在三个表中的任何一个表中查找 IP 地址的匹配项，但我的查询告诉我我正在查看的列不明确？

SELECT COUNT(*) 
FROM `zz_tview`,`zz_tview1`,`zz_tview3` 
WHERE `ipaddress` ="192.168.01.01"

因此，我收到此消息“where 子句中的列 'ipaddress' 不明确”，我将如何首先构造它以使其工作，其次使查询不会太重，因为表有数千行？

Answer 1

听起来你想要这个，但这会产生一个笛卡尔结果，这很可能不是你想要的结果：

SELECT COUNT(*) 
FROM `zz_tview`,`zz_tview1`,`zz_tview3` 
WHERE `zz_tview`.`ipaddress` ="192.168.01.01"
  OR `zz_tview1`.`ipaddress` ="192.168.01.01"
  OR `zz_tview3`.`ipaddress` ="192.168.01.01"

您应该真正将其构造为JOIN：

SELECT COUNT(*) 
FROM `zz_tview` v
INNER JOIN `zz_tview1` v1
    ON v.id = v1.id  --- use the column that would join these values
INNER JOIN `zz_tview3` v3
    ON v.id = v3.id  --- use the column that would join these values
WHERE v.`ipaddress` ="192.168.01.01"
      OR v1.`ipaddress` ="192.168.01.01"
      OR v3.`ipaddress` ="192.168.01.01"

如果您JOIN无法使用表格，那么您可以使用类似于以下内容的内容：

select sum(total)
from
(
    SELECT count(*) as `total`
    FROM `zz_tview` v
    where v.`ipaddress` ="192.168.01.01"
    union all
    SELECT count(*) as `total`
    FROM `zz_tview1` v1
    where v1.`ipaddress` ="192.168.01.01"
    union all
    SELECT count(*) as `total`
    FROM `zz_tview3` v3
    where v3.`ipaddress` ="192.168.01.01"
) src