I’ve had to do this a couple of times and I just realized I haven’t written about it anywhere.
If you need to SELECT a field from a row that returns different content based on the content of the field, you’d think, based on previous programming experience, that your code would look something like this.
SELECT IIF(field=2,"content true","content false") FROM DB
But you’d be wrong.
No, the people who created SQL thought a syntax with a little richer flexibility would do the trick. Why limit ourselves to two states when multiple states will do?
SELECT CASE field WHEN 2 THEN "content true"
ELSE "content false" END FROM DB
In fact you can have multiple WHEN conditions in your code
SELECT CASE field WHEN 1 THEN 'One' WHEN 2 THEN 'Two' WHEN 3 THEN 'Three' END FROM DB
You can also use multiple fields
SELECT CASE WHEN field1 = 1 THEN 'field one' WHEN field2 = 2 THEN 'field two' ELSE 'Something else' END FROM DB
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