sql condition for multi table

Question

Good day everyone,

I want to ask a question about SQL I have 2 tables :

tuser (
  id_user,
  username,
  password,
  name,
  level
)
tstatus(
  id_status,
  id_user,
  status)

*tuser has 5 rows tstatus has 2 rows

i'm doing this query

SELECT * 
FROM tuser,tstatus 
WHERE tuser.id_user = tstatus.id_user 
  AND tuser.level = 'teacher' 
  AND tuser.name LIKE '%" . $queryString . "%' 
ORDER BY tuser.name 
LIMIT 5

The results from mysql_fetch_array only returns 2 rows of user data.

This is because the tstatus table has only 2 rows and could not match any id_user to join to in the tuser table, the problem here is to dynamically fill the tstatus fields can fill or null it..

Can somebody help me fix the query without modifying the table structure?

thanks

Answer 1

As best as I can understand you, I believe you're looking for something like this:

SELECT
    *
FROM
    tuser
LEFT JOIN
    tstatus USING (id_user)
WHERE
    tuser.level = 'teacher'
AND
    tuser.name LIKE '%" . $queryString . "%'
ORDER BY
    tuser.name
LIMIT 5

This will select all the users with a level of 'teacher' and a name that contains the query string -- even those which don't have a corresponding status (the value of any tstatus field will be NULL .

Answer 2

您可以进行左连接，以便所有tuser都在其中：

SELECT * FROM tuser left join tstatus on tuser.id_user = tstatus.id_user WHERE tuser.level = 'teacher' and tuser.name LIKE '%" . $queryString . "%' ORDER BY tuser.name LIMIT 5

Answer 3

use a left join instead.

SELECT tu.*, ts.status FROM tuser tu
LEFT JOIN tstatus ts ON tu.id_user = ts.id_user
WHERE tu.level ='teacher'

You may add other where statements as needed

Answer 4

use a left join. the USING keyword will remove the duplicate user_id field.

SELECT * 
FROM tuser tu
LEFT JOIN tstatus ts USING (user_id)
WHERE tu.level ='teacher'
AND tuser.name LIKE '%" . $queryString . "%' 
ORDER BY tuser.name 
LIMIT 5