Question

说我有3张桌子：

p，r和l

我想选择每个表中有多少行，并将它们定义为表名的变量。

$sevenQ = mysql_query("SELECT count(*) FROM `p` AS p WHERE `added` LIKE '" . $today . "%' union 
SELECT count(*) FROM `r` AS r WHERE `added` LIKE '" . $today . "%' union
SELECT count(*) FROM `l` AS l WHERE `added` LIKE '" . $today . "%'");

$sevenQ['p'] = total amount of rows in p;
$sevenQ['r'] = total amount of rows in r;
$sevenQ['l'] = total amount of rows in l;

如何返回前3个变量进行此类查询？

Answer 1

select count(*) from tablea where ... union select count(*) from tableb where ... union select count(*) from tablec where ...;

您将获得三行，其中包含三个表的行数。（在mysql 5上测试）

关于您的更新：

你的例子无法奏效。 AS 关键字也以错误的方式使用。你应该做点什么：

$res = mysql_query("SELECT \"p\" AS name, count(*) AS cnt FROM `p` WHERE `added` LIKE '" . $today . "%' union 
SELECT \"r\" AS name, count(*) AS cnt FROM `r` WHERE `added` LIKE '" . $today . "%' union
SELECT \"l\" AS name, count(*) AS cnt FROM `l` WHERE `added` LIKE '" . $today . "%'");

while( $row = mysql_fetch_array($res) ){
    $sevenQ[$row['name']] = $row['cnt'];
}

（未经测试的代码）

Answer 2

为什么不使用三个select count(*) from tablename?

Answer 3

你可以尝试（这是未经测试的）：

select "tablea" as name, count(*) as total from tablea where stuff=1
union "tableb", count(*) from tableb where stuff=1
union "tablec", count(*( from tablec where stuff=1

您可能需要进行一些语法更改，这台机器无法访问mysql来解析它以确保。

这应该给你

name  total
tablea  5
tableb 10
tablec  2

Answer 4

如果你想要多个表的行数总和，请尝试这个... 用你的表名替换'table1'，table2，table3 ...... 选择sum（t.total）from（SELECT count（）作为总FROM table1作为联合SELECT计数（）作为总FROM table2作为b联合SELECT计数（* ）作为总数来自table2作为c）和t

mySQL Join，如何从多个表中获取行数？

4 个答案: