Обсуждение: viewing/altering the "ON DELETE CASCADE" constraint
Hello All- I'm sure this is a FAQ, but I cannot find anything in the docs that directly addresses this. How can I determine if a column 1) has a foreign key constraint, and 2) if that fkey constraint includes "ON DELETE CASCADE"? I've tried the various "\d"-type commands in psql to no avail. Finally, assuming you have a column that *has* a fkey constraint, but not the additional "ON DELETE CASCADE" portion, how would you go about adding "ON DELETE CASCADE" to the column? TIA, -Jon PS: PostgreSQL v7.2.1 PSS: I'm happy to receive a RTFM, if you would be so kind as to also point to where in the FM these things might be... PSSS: Searching the mailing lists on http://archives.postgresql.org/ is returning an error message: could not connect to server: Connection refused Is the server running on host db.postgresql.org and accepting TCP/IP connections on port 5433? -- -**-*-*---*-*---*-*---*-----*-*-----*---*-*---*-----*-----*-*-----*--- Jon Lapham Extracta Moléculas Naturais, Rio de Janeiro, Brasil email: lapham@extracta.com.br web: http://www.extracta.com.br/ ***-*--*----*-------*------------*--------------------*---------------
On Mon, 22 Jul 2002, Jon Lapham wrote: > Hello All- > > I'm sure this is a FAQ, but I cannot find anything in the docs that > directly addresses this. > > How can I determine if a column 1) has a foreign key constraint, and 2) > if that fkey constraint includes "ON DELETE CASCADE"? I've tried the > various "\d"-type commands in psql to no avail. > > Finally, assuming you have a column that *has* a fkey constraint, but > not the additional "ON DELETE CASCADE" portion, how would you go about > adding "ON DELETE CASCADE" to the column? The best place to get info on this is at http://techdocs.postgresql.org/ There are a few things on referential integrity there that I believe describe how to get the info on the constraints. As for changing the constraint, you'll probably need to drop the constraint (dropping the triggers) and then add it with alter table add constraint probably.
Stephan Szabo wrote: > On Mon, 22 Jul 2002, Jon Lapham wrote: >>How can I determine if a column 1) has a foreign key constraint, and 2) >>if that fkey constraint includes "ON DELETE CASCADE"? I've tried the >>various "\d"-type commands in psql to no avail. >> >>Finally, assuming you have a column that *has* a fkey constraint, but >>not the additional "ON DELETE CASCADE" portion, how would you go about >>adding "ON DELETE CASCADE" to the column? > > > The best place to get info on this is at > http://techdocs.postgresql.org/ > Yup, thanks Stephan. I've never seen this site, it looks like there is a lot of good info there. Joel Burton's "Hacking Referential Integrity & Hacking the Referential Integrity Tables" has everything I needed. http://techdocs.postgresql.org/techdocs/hackingreferentialintegrity.php -Jon -- -**-*-*---*-*---*-*---*-----*-*-----*---*-*---*-----*-----*-*-----*--- Jon Lapham Extracta Moléculas Naturais, Rio de Janeiro, Brasil email: lapham@extracta.com.br web: http://www.extracta.com.br/ ***-*--*----*-------*------------*--------------------*---------------