records with same value in diff column

[Alicia]

Hi,

 

Can somebody assist me on this :

 

What I need is to check whether UserA and UserB (which has their own unique ID in Column A) has the same transaction ID in column B under the same table.

 

In short, I just want to compare 2 users ID which I already know (column A) and check whether have the same transaction ID in column B.

 

Please advise and thanks.

[Mchl]

SELECT t1.columnB= t2.columnB FROM table AS t1 CROSS JOIN table AS t2 WHERE t1.columnA=? AND t2.columnA= ?

[Alicia]

Hi,

 

but both records are in the same table. So it should not use the t1 and t2 join right?

 

t1 is table 1 and t2 is table 2 right?

[Mchl]

They are just aliases for same table. You can join table to itself.

[Alicia]

I tried this :

 

SELECT * FROM f_users WHERE `user_id`='9' AND `user_id`='1595' but it returns nothing. Did I miss something.

 

Please advise. Thank you

[Mchl]

user_id cannot be 9 AND 1595 at one time.

Did you try my solution?

SELECT t1.columnB = t2.columnB FROM f_users AS t1 CROSS JOIN f_users AS t2 WHERE t1.user_id= 1595 AND t2.user_id= 9

[Alicia]

actually what i should replace with t1 and t2 in your query since it is under the same table?

 

Please advise and thanks

[Mchl]

Nothing. These are just aliases for table f_users, because it is used twice in one query. All you have to do is just replcae 'columnB' with actual column name you want to compare.