Question

I have the following table for storing user data:

e.g.

TABLE: users
COLUMNS:
...
maritalStatus (INT)   - FK
gender        (CHAR)
occupation    (INT)   - FK
...

Now I want to compare two users in this table to see how many columns match for any two given users (say user X & user Y)

I am doing it via mySQL Stored Procedures by getting each value separately and then comparing them

e.g.

    SELECT maritalStatus from users where userID = X INTO myVar1;
    SELECT maritalStatus from users where userID = Y INTO myVar2;

    IF myVar1 = myVar2 THEN

    ...

    END IF;

Is there a shorter way using an SQL query where I can compare two rows in a table and see
which columns are different? I dont need to know how much different they actually are, just
need to know if they contain the same value. Also I will only be comparing selected columns,
not every column in the user table.

Answer 1

This will select the number of columns that are not the same for user x and user y:

SELECT ( u1.martialStatus <> u2.martialStatus )
     + ( u1.gender        <> u2.gender        )
     + ( u1.occupation    <> u2.occupation    )
FROM
  users u1,
  users u2
WHERE u1.id = x
  AND u2.id = y