Re: [sqlite] ADD UNIQUE CONSTRAINT
Thank you, I was wondering about adding a new constraint to an existing column that is currently holding data. On Sun, Oct 10, 2010 at 10:54 AM, P Kishor <punk.k...@gmail.com> wrote: > On Sun, Oct 10, 2010 at 2:45 AM, Fadhel Al-Hashim <fad...@gmail.com> > wrote: > > Good day, > > > > is it possible to Alter a table and add a unique constraint on one or > more > > columns? > > > > See http://www.sqlite.org/lang_altertable.html > > In particular -- > > "The ADD COLUMN syntax is used to add a new column to an existing > table. The new column is always appended to the end of the list of > existing columns. The column-def rule defines the characteristics of > the new column. The new column may take any of the forms permissible > in a CREATE TABLE statement, with the following restrictions: > > The column may not have a PRIMARY KEY or UNIQUE constraint. > The column may not have a default value of CURRENT_TIME, CURRENT_DATE, > CURRENT_TIMESTAMP, or an expression in parentheses. > If a NOT NULL constraint is specified, then the column must have a > default value other than NULL. > If foreign key constraints are enabled and a column with a REFERENCES > clause is added, the column must have a default value of NULL. > Note also that when adding a CHECK constraint, the CHECK constraint is > not tested against preexisting rows of the table. This can result in a > table that contains data that is in violation of the CHECK constraint. > Future versions of SQLite might change to validate CHECK constraints > as they are added." > > > thanks, > > > > fadhel > > ___ > > sqlite-users mailing list > > sqlite-users@sqlite.org > > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > > > > -- > Puneet Kishor http://www.punkish.org > Carbon Model http://carbonmodel.org > Charter Member, Open Source Geospatial Foundation http://www.osgeo.org > Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor > Nelson Institute, UW-Madison http://www.nelson.wisc.edu > --- > Assertions are politics; backing up assertions with evidence is science > === > ___ > 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
[sqlite] ADD UNIQUE CONSTRAINT
Good day, is it possible to Alter a table and add a unique constraint on one or more columns? thanks, fadhel ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Delete from A what is not in B
yes PRIMARY KEY (x,y,z) On Sat, Oct 2, 2010 at 9:10 PM, Simon Slavin <slav...@bigfraud.org> wrote: > > On 2 Oct 2010, at 1:15pm, Fadhel Al-Hashim wrote: > > > I did not add indices on those columns assuming that being PK is enough? > is > > that right? > > How did you define the primary keys ? Was it PRIMARY KEY (x,y,z) ? > > Simon. > ___ > 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
Re: [sqlite] Delete from A what is not in B
I did not add indices on those columns assuming that being PK is enough? is that right? On Sat, Oct 2, 2010 at 3:08 PM, Drake Wilson <dr...@begriffli.ch> wrote: > Quoth Fadhel Al-Hashim <fad...@gmail.com>, on 2010-10-02 14:51:59 +0300: > > tryingA.x<>B.xANDA.y<>B.y ANDA.z<>B.z would just > > hang. > > Huh? How are you using that expression? > > I'd use DELETE FROM a WHERE NOT EXISTS (SELECT * FROM b WHERE a.key = > b.key) > with a suitable composite equality in the subselect. > > > Is my data too big for SQLIte? is it really hanging or it could be taking > 3 > > days? > > Table A and (particularly) table B both have indices on those columns, > right? > > ---> Drake Wilson > ___ > 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
[sqlite] Delete from A what is not in B
Good day everyone. I have two tables that contain about 5 million records. I am trying to write an SQL command to delete rows from table A with PK (x,y,z) where PK (x,y,z) is not in table B. tried using "NOT IN" but my PK is composite. tryingA.x<>B.xANDA.y<>B.y ANDA.z<>B.z would just hang. Is my data too big for SQLIte? is it really hanging or it could be taking 3 days? thank you, fadhel ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
