Thank you for the fast and clear answers! Cheers Jan
D. Richard Hipp schrieb: > On Apr 13, 2009, at 2:19 PM, jan wrote: > >> Hi, >> >> is there a way to query the check constraints added to a column >> definition? >> > > No. > > Actually, SQLite does not support CHECK constraints assigned to > individual columns. Sure, you can include the CHECK constraint on an > individual column when you create the table, but what SQLite does > internally is coalesce all of the column CHECK constraints into one > big whole-table CHECK constraint. In other words, if you type this: > > CREATE TABLE t1( > a INTEGER CHECK( a<10 ), > b VARCHAR(10) CHECK( length(b)>5 > ); > > SQLite will actually implemented it as: > > CREATE TABLE t1( > a INTEGER, > b TEXT, > CHECK( a<10 AND length(b)>5 ) > ); > > To put it another way, all CHECK constraints on a table are gathered > together into a single boolean expression that is evaluated after > every INSERT or UPDATE and fails the operation if that single > expression is false. SQLite does not keep track of where the > individual terms in the CHECK constraint originally came from. > > D. Richard Hipp > d...@hwaci.com > > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
