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Nested Types

  • November 14, 2015 at 11:23 pm

    #74798

    Comments posted to this topic are about the item Nested Types

  • November 14, 2015 at 11:24 pm

    #1839840

    Good question, learned somthin new 2day, keep up these kind of questions, thanx 🙂

    Thanks & Best Regards,
    Hany Helmy
    SQL Server Database Consultant

  • November 16, 2015 at 12:53 am

    #1839876

    good question. Thanks for sharing.

  • November 16, 2015 at 5:28 am

    #1839917

    I've never had to use user-defined types in the database before, so I learned something new. I think I knew this because of the reading I did from last week's question on custom types. Thanks, Steve.

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  • November 16, 2015 at 9:16 am

    #1839999

    Simple and nice - thanks, Steve!

  • November 16, 2015 at 11:23 pm

    This was removed by the editor as SPAM

  • November 16, 2015 at 11:41 pm

    #1840202

    Good question, dismissed the correct answer after thinking about he batch option ;-), thanks Steve

    ...

  • November 17, 2015 at 4:54 am

    #1840269

    Nice one, thanks.

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  • November 17, 2015 at 5:02 am

    #1840273

    Nice simple question.

    But although it is nice and simple and it's easy to see which option is intended to be correct, pedantically speaking perhaps none of them is correct - the three wrong answers simply because they are wrong and the "right" answer because "email" (according to the CREATE TYPE BOL page) is not a UDT (UDTs are based on CLR assemblies, not on base types), it's a type alias, so the reason the second create type statement fails has nothing to do with UDTs - the reason it fails is that nothing but the 28 base types (sysname is not a base type, it's a type alias) can be used as the base for a type alias . Of course user-created type aliases appear in sys.types flagged is-user-defined, so there seems to be some confusion even within Microsoft as to whether type aliases (other that MS-defined ones like systype) are UDTs or not.

    edit: 10 minutes after posting it suddenly clicked that type aliases are sometimes called "User Defined DataTypes" and the CLR-based types are always "User Defined Types" - maybe the MS terminology for this stuff is even more confused that I thought.

    Tom

  • November 23, 2015 at 2:16 pm

    #1841864

    Thanks for the question.

  • November 24, 2015 at 7:39 am

    #1842054

    I ran this and got the below error.

    The base type "email" is not a valid base type for the alias data type.

    Never had a reason personally to create types, but have been in existing DBs where they exist. Good to know if I ever need to use them.

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