Question

I have a table with fields id, text, and title. There may be multiple rows with the same title (title is not unique). Additionally, id is the primary key.

I need only to know if there are at least one row with title=”A” that contains the string “aaa” in text, and additionally at least one row with title=”B” that contains the string “bbb” in text.

This is what I tried:

mysql> SELECT (SELECT text FROM table WHERE title = 'A') as aText, (SELECT text FROM table WHERE title = 'B') as bText;

I had planned on parsing the values of aText and bText for the strings “aaa” and “bbb” respectfully with PHP. However, I have two issues:

1) Major issue: Due to title not being unique, the subqueries may return multiple rows. MySQL breaks on that happening with this error:

ERROR 1242 (21000): Subquery returns more than 1 row

2) Minor issue: The reason that I am parsing in PHP is to avoid using MySQL’s LIKE operator. Would I be better off doing the parsing of the string right there in MySQL as such:

mysql> SELECT (SELECT text FROM table WHERE title = 'A' AND text LIKE '%aaa%') as aText, (SELECT text FROM table WHERE title = 'B' AND text LIKE '%bbb%') as bText;

Answer 1

It is probably not good form to answer one’s own question, but for the sake of the fine archives at the expense of my karma:

The query that I employed is:

SELECT count(*) FROM (
    SELECT DISTINCT title FROM (
        SELECT title, text FROM table WHERE title IN ('A', 'B')
    )
    AS filtered
    WHERE (title='A' AND text LIKE '%aaa%')
       OR (title='B' AND text LIKE '%bbb%')
)
AS allResults;

The innermost query gets everything with a good title, the next query gets distinct titles for the real results. This setup ensures that the LIKE clause will not run on the entire table. I then wrap all that in a count, and if if equals 2 then I know that each condition was met.

Thank you everyone who contributed, I gained quite some insight from your answers!