SQL CONCAT String + Column in WHERE clause

Question

I got a numeric value in Foo.A and it has its equivalent in Bar but with a string prefix ("Z"). I'm trying to append the "Z" to the Bar.A col value. I also tried with CONCAT but without any success. This following codes returns "Unknown column Z".

UPDATE Foo, Bar
SET Foo.B = Bar.B
WHERE Foo.A = Z + Bar.A

For example 14 (Foo.A) = Z14 (Bar.A).

Answer 1

If your syntax works, then it is likely you are using MySQL. In any case, the problem is that you need quotes around string constants. So try this:

UPDATE Foo join
       Bar
       on Foo.A = concat('Z', Bar.A)
    SET Foo.B = Bar.B;

You should always use single quotes for string and date constants, regardless of the database. That is the ANSI standard and it reduced the possibility of error.

Answer 2

You are missing the single quotes around Z i.e. your code should be:

UPDATE Foo, Bar
SET Foo.B = Bar.B
WHERE Foo.A = CONCAT('Z', Bar.A);