I’m aware that many of my readers of this site likely already know how to write sql to generate sql, or sql generators, but it’s not really much of a data blog if I don’t mention it. It’s also important to mention the time value this trick represents, with a few minutes of time, you can generate thousands of lines of code that would otherwise take hours to write. Let’s chat about one of the first things I learned about SQL which, no doubt, blew my mind:
Generate SQL with SQL.
Or to put another way, generating SQL statements via a single SQL command. Really cool stuff if you haven’t seen this before, keep reading!
Let’s say you wanted to find the number of badges for each type of badge in a table of badges. This is quite easy with a simple query, but let’s see how we can do it by writing SQL with SQL:
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SELECT 'SELECT CAST(''' + BADGES.NAME + '''AS VARCHAR(50)), COUNT(1) FROM BADGES WHERE BADGES.NAME = ''' + BADGES.NAME + ''' UNION ALL' FROM BADGES GROUP BY BADGES.NAME; |
