I want to create a column of data type having only ‘mm-dd’ values. Is it possible and if yes how should I do it?
Note: Instead of “2022-06-07“, I want “07-06“
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Answer
There is no date type that can store that format – in fact none of the date types store a date and/or time in any of the formats you typically recognize.
For your specific requirement, that looks like a char(5) for the data type, but how you constrain it so that it will only accept valid date values, I have no idea. You’d think this would work:
CHECK (TRY_CONVERT(date, string_column + '-2022', 105) IS NOT NULL)
But what about leap years? February 29th is sometimes valid, but you’ve thrown away the only information that can make you sure. What a bunch of mess to store your favorite string and trust that people aren’t putting garbage in there.
Honestly I would store the date as a date, then you can just have a computed column (or a column in a view, or just do this at query time:
d_slash_m_column AS CONVERT(char(5), date_column, 105)
Why not just in your query (or only in a view) say:
[output] = CONVERT(char(5), data_in_the_right_type, 105)
?
I’d personally stay away from FORMAT(), for reasons I’ve described here: