Question

这就是我的表格：

id | name | value
-----------------
 1 | user1|  1
 2 | user2|  1
 3 | user3|  3
 4 | user4|  8
 5 | user5|  6
 6 | user7|  4
 7 | user8|  9
 8 | user9|  2

我想要做的是在一个查询中选择所有其他用户，其值是user1的值低于其值加3，高于其值减去3或等于其值。

这样的事情：

$result = mysqli_query($con,"SELECT * FROM users WHERE value<'4' OR value>'-2'") or die("Error: ".mysqli_error($con));

while($row = mysqli_fetch_array($result))
    {
        echo $row['name'].'<br/>';
    }

问题是每次运行查询时，users1的值都会有所不同。

Answer 1

抱歉蹩脚的名字，但这应该有效：

注意：我将您的数据命名为“st”。

SELECT b.user, a.value as "user1val", b.value as "otheruservalue" FROM st as a
      join st as b
      on a.user = "user1" and a.user != b.user
 where
    (b.value > (a.value - 3)) and (b.value < (a.value + 3))

我们通过连接相同的表获得user1的唯一值和其他用户的值。之后我们只是做一些简单的比较来过滤具有合适值的行。

Answer 2

$user1 = mysql_fetch_assoc(mysql_query("SELECT `value` FROM `users` WHERE id='1'"));

$result = mysql_query("SELECT * FROM `users` WHERE value<'".$user1['value']."+3' OR value>'".$user1['value']."-3'");

Answer 3

或嵌套查询：

$result = mysqli_query($con, "select * from `users` where `value` < (select `value` from `users` where `name`='user1')+3 OR `value` > (select `value` from `users` where `name`='user1')-3");

PHP / Mysql：2在一个查询中从同一个表中选择

3 个答案: