使用php从下拉列表中获取值，从两个Mysql表中显示数据 [英] display data from two Mysql tables by getting values from drop down list using php

问题描述

我有两个表格国家/地区，其字段为

I have two tables countries, location whose fields are

_countries
    countryid(Primary Key)
    countryname

_location
    locationid(primarykey)
    locationname
    countryid(Foreign key from countries table)

使用JavaScript，AJAX和php完成每件事情，当用户从下拉列表中选择一个国家/地区时，每个国家/地区的位置将被移除，但是mysql查询不会工作
我正在使用下面的查询

Every thing is done using JavaScript,AJAX and php that when a user selects a country from drop down list, locations against each country will be displaced but the mysql query is not working I am Using the Below Query

$sql="SELECT _location.locationname, _countries.countryname FROM _location 
INNER JOIN _countries ON _location.countryid='".$q."'";

//$q is the countryid selected from drop down list i got it through javascript and php

下拉列表从国家表填入
我的问题是当用户从下拉列表中选择一个国家名称时，
将获取位置名称的mysql查询对每个国家的名字和显示这样的数据

The drop down list is populated from the countries table My Question is when a user selects a country name from the drop down list what will be the mysql query that fetch the location name against each country name and display data like this

||Location name||Country Name||
  Islamabad       Pakistan
  Karachi         Pakistan

推荐答案

 $sql = "SELECT l.locationname, c.countryname
FROM
_countries c
LEFT JOIN _location l ON c.countryid = l.countryid
WHERE c.countryid = ".(int)$q;

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