MySQL select query with multiple conditions

Question

I have written a MySQL query but it doesn\'t seem to be working, because the result is empty. Is there any mistake in my code?

$result = mysql_query(
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Answer 1

Lets suppose there is a table with following describe command for table (hello)- name char(100), id integer, count integer, city char(100).

we have following basic commands for MySQL -

select * from hello;
select name, city from hello;
etc 

select name from hello where id = 8;
select id from hello where name = 'GAURAV';

now lets see multiple where condition -

select name from hello where id = 3 or id = 4 or id = 8 or id = 22;

select name from hello where id =3 and count = 3 city = 'Delhi';

This is how we can use multiple where commands in MySQL.

Answer 2

I would use this query:

SELECT
  user_id
FROM
  wp_usermeta 
WHERE 
  (meta_key = 'first_name' AND meta_value = '$us_name') OR 
  (meta_key = 'yearofpassing' AND meta_value = '$us_yearselect') OR 
  (meta_key = 'u_city' AND meta_value = '$us_reg') OR
  (meta_key = 'us_course' AND meta_value = '$us_course')
GROUP BY
  user_id
HAVING
  COUNT(DISTINCT meta_key)=4

this will select all user_id that meets all four conditions.

Answer 3

You have conditions that are mutually exclusive - if meta_key is 'first_name', it can't also be 'yearofpassing'. Most likely you need your AND's to be OR's:

$result = mysql_query("SELECT user_id FROM wp_usermeta 
WHERE (meta_key = 'first_name' AND meta_value = '$us_name') 
OR (meta_key = 'yearofpassing' AND meta_value = '$us_yearselect') 
OR (meta_key = 'u_city' AND meta_value = '$us_reg') 
OR (meta_key = 'us_course' AND meta_value = '$us_course')")

Answer 4

@fthiella 's solution is very elegant.

If in future you want show more than user_id you could use joins, and there in one line could be all data you need.

If you want to use AND conditions, and the conditions are in multiple lines in your table, you can use JOINS example:

SELECT `w_name`.`user_id` 
     FROM `wp_usermeta` as `w_name`
     JOIN `wp_usermeta` as `w_year` ON `w_name`.`user_id`=`w_year`.`user_id` 
          AND `w_name`.`meta_key` = 'first_name' 
          AND `w_year`.`meta_key` = 'yearofpassing' 
     JOIN `wp_usermeta` as `w_city` ON `w_name`.`user_id`=`w_city`.user_id 
          AND `w_city`.`meta_key` = 'u_city'
     JOIN `wp_usermeta` as `w_course` ON `w_name`.`user_id`=`w_course`.`user_id` 
          AND `w_course`.`meta_key` = 'us_course'
     WHERE 
         `w_name`.`meta_value` = '$us_name' AND         
         `w_year`.meta_value   = '$us_yearselect' AND 
         `w_city`.`meta_value` = '$us_reg' AND 
         `w_course`.`meta_value` = '$us_course'

Other thing: Recommend to use prepared statements, because mysql_* functions is not SQL injection save, and will be deprecated. If you want to change your code the less as possible, you can use mysqli_ functions: http://php.net/manual/en/book.mysqli.php

Recommendation:

Use indexes in this table. user_id highly recommend to be and index, and recommend to be the meta_key AND meta_value too, for faster run of query.

The explain:

If you use AND you 'connect' the conditions for one line. So if you want AND condition for multiple lines, first you must create one line from multiple lines, like this.

Tests: Table Data:

          PRIMARY                 INDEX
      int       varchar(255)    varchar(255)
       /                \           |
  +---------+---------------+-----------+
  | user_id | meta_key      | meta_value|
  +---------+---------------+-----------+
  | 1       | first_name    | Kovge     |
  +---------+---------------+-----------+
  | 1       | yearofpassing | 2012      |
  +---------+---------------+-----------+
  | 1       | u_city        | GaPa      |
  +---------+---------------+-----------+
  | 1       | us_course     | PHP       |
  +---------+---------------+-----------+

The result of Query with $us_name='Kovge' $us_yearselect='2012' $us_reg='GaPa', $us_course='PHP':

 +---------+
 | user_id |
 +---------+
 | 1       |
 +---------+

So it should works.

Answer 5

also you can use "AND" instead of "OR" if you want both attributes to be applied.

select * from tickets where (assigned_to='1') and (status='open') order by created_at desc;