CODEWITHSUNDEEP
mysql
Rahul Sarkar
Rahul Sarkar

Reputation: 89

Check if a particular ID exists in another table or not using MySQL join

I have two SQL tables, and I like to have the result shown below.

table_1

id      userId
---------------
1           u1
2           u2
3           u3
4           u4
5           u5

table_2

userId      flag
-----------------
u1          1
u4          0

Result I need

id      userId      flag
------------------------
1           u1      1
2           u2      Null
3           u3      Null
4           u4      0
5           u5      Null

Upvotes: 1

Views: 6283

Answers (3)

Jens
Jens

Reputation: 69440

use the left outer join:

select table_1.id, table_1.userid, table_2.flag 
from table_1 
  left outer join table_2 on table_1.userid=table_2.userid

Upvotes: 1

nimour pristou
nimour pristou

Reputation: 153

you can use join or Under-expression for join :

select 
t1.id,
t1.userid,
t2.flag  
from table_1  t1
inner join table_2 t2
on t1.userid = t2.userid

under-expression 

select 
t1.id,
t1.userid,
(select flag from table_2 t2 WHERE t1.userid=t2.userid) as flag
from table_1  t1

Upvotes: 0

K.Suthagar
K.Suthagar

Reputation: 2306

You can use this following LEFT JOIN for the purpose, It will give all right table data with matched right table data .

SELECT * FROM table_1 LEFT JOIN table_2 on table_1.userId=table_2.userId

Upvotes: 2

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