type checking SQL expressions

Jean Morissette <jean.morissette666@videotron.ca>
20 Mar 2005 11:12:41 -0500

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type checking SQL expressions jean.morissette666@videotron.ca (Jean Morissette) (2005-03-20)
Re: type checking SQL expressions gneuner2@comcast.net (George Neuner) (2005-03-24)
Re: type checking SQL expressions Brian.Inglis@SystematicSW.ab.ca (2005-03-25)
Re: type checking SQL expressions gene@abhost.us (Gene Wirchenko) (2005-03-27)
Re: type checking SQL expressions Brian.Inglis@SystematicSW.ab.ca (Brian Inglis) (2005-03-31)
Re: type checking SQL expressions jean.morissette666@videotron.ca (Jean Morissette) (2005-04-11)
Re: type checking SQL expressions gneuner2@comcast.net (George Neuner) (2005-04-16)
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From: Jean Morissette <jean.morissette666@videotron.ca>
Newsgroups: comp.compilers
Date: 20 Mar 2005 11:12:41 -0500
Organization: Compilers Central
Keywords: SQL, types, question
Posted-Date: 20 Mar 2005 11:12:41 EST

Hi,
I want to build a simple SQL compiler and I would like to know if a
formal specification of the type system used in SQL has been written
somewhere? It seems to me that the type system of SQL is incoherent.
I let an exemple below that explain my affirmation.


Thank
-Jean


If the type of the request "SELECT column1, column2 FROM table1" is
bag(tuple(type_of_column1, type_of_column2)),


the type of column3 in the request "SELECT column1 FROM table2 WHERE column3
IN (SELECT column1 FROM table1)" should be tuple(type_of_column1).


But in this request:
"SELECT column1 FROM table2 WHERE column3 > 9"
the type of column3 is integer instead of tuple(integer)




*Note that I'm not sure because I don't have a formal specification of the
type system.
[Interesting question. I've never seen a type spec beyond the elementary
data types. -John]


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