Re: [sqlite] Error in documentation for FOREIGN KEY ?

[Simon Slavin]

On 14 Mar 2010, at 11:13pm, Kees Nuyt wrote:

> Well, it is consistent, when you take 
> http://www.sqlite.org/syntaxdiagrams.html#table-constraint
> into account.
> 
> CREATE TABLE is the only statement where references
> constraints can be defined. Have a look at
> http://www.sqlite.org/lang_createtable.html
> 
> A column definition can contain a foreign-key-clause, which
> is simply a REFERENCES column-constraint.

Got it.  Thanks to Kees and Jay.

Simon.
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Re: [sqlite] Error in documentation for FOREIGN KEY ?

[Kees Nuyt]

On Sun, 14 Mar 2010 22:04:18 +, Simon Slavin
 wrote:

> I was trying to work out if I could add a FOREIGN KEY to a table after
> it is originally created, using the ALTER TABLE command. I think there's an 
> error on
>
>http://www.sqlite.org/syntaxdiagrams.html
>
> I cannot find anything on that page that includes the actual words 'FOREIGN 
> KEY'.  The section
>
>http://www.sqlite.org/syntaxdiagrams.html#foreign-key-clause
>
> starts with the word 'REFERENCES'.  I traced up and down the hierarchy 
> but I couldn't find 'FOREIGN KEY'.  This is not consistent with the
> description of creating FK constraints as described in
>
>http://www.sqlite.org/foreignkeys.html

Well, it is consistent, when you take 
http://www.sqlite.org/syntaxdiagrams.html#table-constraint
into account.

CREATE TABLE is the only statement where references
constraints can be defined. Have a look at
http://www.sqlite.org/lang_createtable.html

A column definition can contain a foreign-key-clause, which
is simply a REFERENCES column-constraint.

In a table-constraint (defined after all column definitions)
a REFERENCES constraint is introduced by the FOREIGN KEY
keyword.

The difference between the two is that a table constraint
can (but doesn't have to) use composite keys, consisting of
more than one column.

>Simon.
-- 
  (  Kees Nuyt
  )
c[_]
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Re: [sqlite] Error in documentation for FOREIGN KEY ?

[Jay A. Kreibich]

On Sun, Mar 14, 2010 at 10:04:18PM +, Simon Slavin scratched on the wall:

> http://www.sqlite.org/syntaxdiagrams.html
> 
>  I cannot find anything on that page that includes the actual
> words 'FOREIGN KEY'.

  http://www.sqlite.org/syntaxdiagrams.html#table-constraint

  For a column constraint, the FK phrase starts with "REFERENCES...".

  For a table constraint, the FK phrase starts with "FOREIGN KEY...
  REFERENCES...".

> The section
> 
> http://www.sqlite.org/syntaxdiagrams.html#foreign-key-clause
> 
> starts with the word 'REFERENCES'.  I traced up and down the hierarchy
> but I couldn't find 'FOREIGN KEY'.

  If you follow both "Used by" links, and find the reference to the
  child foreign-key-clause, it is pretty obvious.

   -j

-- 
Jay A. Kreibich < J A Y  @  K R E I B I.C H >

"Our opponent is an alien starship packed with atomic bombs.  We have
 a protractor."   "I'll go home and see if I can scrounge up a ruler
 and a piece of string."  --from Anathem by Neal Stephenson
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