mike <mike(at)redtux1(dot)uklinux(dot)net> writes:
> CREATE TABLE public."Invoice_Header"
^^^^^^^^^^^^^^^^
> I am trying to make Inv_ID a primary key as follows
> alter table Invoice_Header ADD CONSTRAINT PK_inv PRIMARY KEY (Inv_ID)
^^^^^^^^^^^^^^
> which runs without error, but nothing changes
I think you have tables named "Invoice_Header" and "invoice_header",
and the latter table is what's getting affected by your ALTER. If you
are going to use mixed-case names then you have to be consistent about
double-quoting them all the time.
regards, tom lane