SQL: search/replace but only the first time a value appears in record

Question

I have html content in the post_content column.

I want to search and replace A with B but only the first time A appears in the record as it may appear more than onc

Answer 1

Alternatively, you could use the functions LOCATE(), INSERT() and CHAR_LENGTH() like this:

INSERT(originalvalue, LOCATE('A', originalvalue), CHAR_LENGTH('A'), 'B')

Full query:

UPDATE wp_posts
SET post_content = INSERT(originalvalue, LOCATE('A', originalvalue), CHAR_LENGTH('A'), 'B');

Answer 2

If you are using an Oracle DB, you should be able to write something like :

UPDATE wp_posts SET post_content = regexp_replace(post_content,'A','B',1,1)

See here for more informations : http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions130.htm

Note : you really should take care of post_content regarding security issue since it seems to be an user input.

Answer 3

To keep the sample of gjreda a bit more simple use this:

UPDATE wp_post
    SET post_content =
            CONCAT(
                REPLACE(LEFT(post_content, 1), 'A', 'B'),
                SUBSTRING(post_content, 2)
            ) 
    WHERE post_content LIKE 'A%';