REPLACE behavior
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Interesting question.
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nice and easy.
thanks.
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+1
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Thanks Auke. I liked the question. Do you have more?
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Interesting, Thanks for the question.
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Even though this is a simple one to remember, when strings are taken from a table ample are the chances that this behavior would be forgotten.
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@Anoo
This is exactly what happened to me and how I found out about this behaviour.
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@auke - And together we learn by sharing our mistakes. Thank you for sharing the question.
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auke.teeninga (3/6/2014)
In many programming languages the third argument wouldn't even be evalutated if the second argument didn't appear in the first argument.All these will just return 'ABC':
SELECT REPLACE('ABC', 'Z', 1)
SELECT REPLACE('ABC', 'Z', CURRENT_TIMESTAMP)
SELECT REPLACE('ABC', 'Z', '#$@%')
This one will return 'ABC' half of the time and NULL the other half.
SELECT REPLACE('ABC', 'Z', CASE WHEN RAND() < 0.5 THEN 'A' END)
I thought of making the problem more complex, but I figured that would result in more people just running the query instead of answering first!
So, although the actual QotD is straightforward, one has to be careful to guard against having anything in the REPLACE statement that evaluates to NULL.
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ronmoses (3/6/2014)
Richard Warr (3/6/2014)
It's anything but logical behaviour and you can only get the question correct if you know that caveat on the REPLACE function (or if you just run the code).Developer A: "We have a bug in this function. Want me to fix it?"
Developer B: "Nah, just document it as normal behavior."
Developer A: "Done."
+1
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