Are you trying to UPDATE or INSERT? The query you have written works with UPDATE. For INSERT: Since "roll_no" is a primary key, your INSERT statement should include "roll_no" in the inserting fields. Let us know if that doesn't answer your question -- Satish Vellanki
On Tue, Jul 8, 2008 at 5:21 AM, Aditya <[EMAIL PROTECTED]> wrote: > Hi, > I am new to postgresql. I have a small problem. I have two tables 1) > students and 2) classes with the following structure - > > Students - > 1) roll_no > 2) name > 3) class > > and Classes - > 1) roll_no > 2) class > > with roll_no being primary key in both the tables. Now I want to > insert the data from the class field in 'classes' into the class field > of 'students'. I tried the following > __________________________________________________________ > > INSERT INTO students (class) > SELECT class FROM classes WHERE students.roll_no = classes.roll_no; > __________________________________________________________ > > I get the following error - > > __________________________________________________________ > ERROR: invalid reference to FROM-clause entry for table "students" > LINE 3: WHERE students.roll_no = classes.roll_no > ^ > HINT: There is an entry for table "students", but it cannot be > referenced from this part of the query. > __________________________________________________________ > > Any suggestions? > > Thanking you, > Aditya Pratap V. > >
