Concatenation with case statement in mysql

Question

I want to generate .sql file with the sql query output . I am doing this with concat statement in sql . I am using case statement in some queries this will be the problem for me.

select concat('insert into x values(',CASE a when B then 'Book' else 'NONE' end , ') on duplicate key update B = values(B)') from author;

select 'insert into x values('+CASE a when B then 'Book' else 'NONE' end +') on duplicate key update B = values(B)' from author;

It also not works because in mysql + used for adding only numbers not for strings .

Is there any way for doing this?.

Answer 1

The problem with the first version is the quotes of things within the string. For instance, you want your string to contain "'Book'"

select concat('insert into x values(',
               (CASE a when 'B' then '''Book''' else '''NONE''' end) ,
              ') on duplicate key update B = values(''B'')'
             )
from author;

I think this quotes al the strings as they should be. I'm guess column A is a character that should be compared to 'B' and not to column B.