Get the values of two fields from a table JOIN

问题

I have a mysql table called districts where all the districts and their id's are stored. I have another table called tbl_units where unit details such as office_address, office_district, factory_address, factory_district are saved.

Now if want to get the names of the districts from their id's by JOIN ing the two tables, how should I write the query ? Because

SELECT u.*, d.district_name
FROM  tbl_unit_details as u,
    tbl_districts as d 
WHERE u.unit_id = '$unit_id' 
    AND u.district_id = d.district_id 
    AND u.factory_district_id = d.district_id 
ORDER BY unit_name

returns only the first , i.e. district name of office.

回答1:

Join the districts table to the units table twice; once for each district type. Use aliases to distinguish each instance of the district table. If you like, you can include the optional AS keyword.

回答2:

try this out maybe it can help

$sql=mysql_query("SELECT u.*,t.* FROM districts as u,tbl_units as t WHERE u.id=t.id");
$row=mysql_fetch_array($sql);
//echo your required result however you want

here u.id represents districs table id and t.id represents tbl_units table id, but in this case your id for tbl_units must be a foreign key.

来源：https://stackoverflow.com/questions/18120256/get-the-values-of-two-fields-from-a-table-join