如何在同一个表中的两个不同列中查找并显示相似词的数量（MySql，PHP）

Question

我有表名relation_country，其中有三列 id、country_a 和 country_b 数据如下...

id   country_a   country_b
1    USA         France
2    Australia   USA
3    France      Australia
4    India       Rassia
5    Rassia      USA
6    France      Rassia
7    USA         India

在这里，我看到 USA 和 Rassia 建立了良好的关系。现在我想知道其中有多少人拥有相似的国家/地区。

say, Rassia has France & India
and USA has also France and India.

我可以查询显示，美国有（法国、澳大利亚、印度） 和 Rassia 有（法国和印度） 但我不能证明，这两个国家与（印度和法国）有相似的关系。

请帮忙。

Answer 1

是的，我为类似于 Rassia 的美国捐款

$USA1 = mysql_query("SELECT * FROM relation_country WHERE country_a= 'USA'");
$USA_numrows1 = mysql_num_rows($USA1);

if($USA_numrows1!=0){
    while($row1 = mysql_fetch_assoc($USA1)){
        $country_b =$row1['country_b'];
        echo $country_b."<br/>";            
    }
}

$USA2 = mysql_query("SELECT * FROM relation_country WHERE country_b= 'USA'"); $USA_numrows2 = mysql_num_rows($USA2);

if($USA_numrows2!=0){
    while($row2 = mysql_fetch_assoc($USA2)){
        $country_a =$row2['country_a'];
        echo $country_a."<br/>";            
    }
}

$russia1 = mysql_query("SELECT * FROM relation_country WHERE country_a= 'russia'"); $russia_numrows1 = mysql_num_rows($russia1);

if($russia_numrows1!=0){
    while($row3 = mysql_fetch_assoc($russia1)){
        $country_b1 =$row3['country_b'];
        echo $country_b1."<br/>";           
    }
}

$russia2 = mysql_query("SELECT * FROM relation_country WHERE country_b= 'russia'"); $russia_numrows2 = mysql_num_rows($russia2);

if($russia_numrows2!=0){
    while($row4 = mysql_fetch_assoc($russia2)){
        $country_a1 =$row4['country_a'];
        echo $country_a1."<br/>";           
    }
}   

Answer 2

抱歉花了这么长时间我不得不将数据放在本地并测试它。

这是您需要的代码：

 (SELECT DISTINCT `country_a` FROM `relation_country` WHERE(`country_b` ='USA' AND (`country_a` IN (SELECT `country_a` FROM `relation_country` WHERE `country_b`= 'Russia') OR `country_a` IN (SELECT `country_b`  FROM `relation_country` WHERE `country_a`='Russia')))) UNION (SELECT DISTINCT `country_b` FROM `relation_country` WHERE(`country_a` ='USA' AND (`country_b` IN (SELECT `country_a` FROM `relation_country` WHERE `country_b`= 'Russia') OR `country_b` IN (SELECT `country_b`  FROM `relation_country` WHERE `country_a`='Russia'))))

采用格式化形式：

 (
 SELECT DISTINCT `country_a`
 FROM `relation_country`
 WHERE (
    `country_b` = 'USA'
    AND (
      `country_a`
      IN (

        SELECT `country_a`
        FROM `relation_country`
        WHERE `country_b` = 'Russia'
      )
      OR `country_a`
      IN (

        SELECT `country_b`
        FROM `relation_country`
        WHERE `country_a` = 'Russia'
       )
     )
   )
 )
 UNION (

 SELECT DISTINCT `country_b`
 FROM `relation_country`
 WHERE (
   `country_a` = 'USA'
   AND (
     `country_b`
     IN (

      SELECT `country_a`
      FROM `relation_country`
      WHERE `country_b` = 'Russia'
     )
    OR `country_b`
    IN (

     SELECT `country_b`
     FROM `relation_country`
     WHERE `country_a` = 'Russia'
    )
   )
  )
 )

注意将 UNION 用于 DISTINCT 值。

Answer 3

如果我理解正确的话，这里是 sql 结果。只是为了使 sql 更易于理解，请创建以下视图。

"create view xcountry as select country_a,country_b from relationship_country union select country_b,country_a from relation_country;"

然后这个选择

"select country_b from xcountry where country_a = 'USA' and country_b in (select country_b from xcountry where country_a = 'Rassia');"

结果是两行；法国和印度。希望这会有所帮助。