October 15, 2024 at 3:36 pm
I've got some code that is supposed to generate a unique key by prefixing an integer with a single character. It's been working fine, but now the integer input is longer than I want for the final column and the result isn't what I expected at all. Both the columns in the result below yield "*". I would have expected CAST to fail and TRY_CAST to return NULL. Can anyone explain what's going on please?
SELECT CAST(10000137 AS VARCHAR(7)), TRY_CAST(10000137 AS VARCHAR(7))
October 15, 2024 at 4:20 pm
That is SQL's method for handling insufficient space on a CAST.
The only safe method would be to use 11 chars. 10 max digits plus the prefix char (assuming you don't allow negative numbers).
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October 16, 2024 at 6:18 am
That is SQL's method for handling insufficient space on a CAST.
I can see why CAST might do that (although I'd expect it to cause an error instead), but why doesn't TRY_CAST give a NULL? That's what the documentation says it will do if the target datatype cannot accept the value.
October 16, 2024 at 8:24 pm
ScottPletcher wrote:That is SQL's method for handling insufficient space on a CAST.
I can see why CAST might do that (although I'd expect it to cause an error instead), but why doesn't TRY_CAST give a NULL? That's what the documentation says it will do if the target datatype cannot accept the value.
Because the target datatype *can* accept the value - it is considered 'Too short to display'. Instead of showing an error - or truncating the data, SQL Server returns the *.
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