Re: Table constraints and INSERT

On 17 maj 2006, at 08.42, Risto Tamme wrote:
> INSERT INTO "PART" ("P_PARTKEY","P_RETAILPRICE") VALUES(999,90109.89);
>
> but it fails: ERROR: new row for relation "PART" violates check
> constraint "PART_check"

The P_PARTKEY column is an integer, which means the expression
P_PARTKEY/10 will yield 99, *not* 99.9.

Try executing

SELECT 90000 + 999/10 + 999/10;

from psql or some GUI-utility; the result is 90108.

> When you check using your head or pocket calculator then this INSERT
> seems to be correct. Is it some floating point mystery?
> Is there some trick?

You must cast the integer column to a float or numeric, try:

SELECT 90000 + 999::numeric/10 + 999::numeric/100;

In your case:

CHECK ("P_RETAILPRICE" = (90000 + "P_PARTKEY"::numeric / 10 +
"P_PARTKEY"::numeric / 100)

Sincerely,

Niklas Johansson
Phone: +46-322-108 18
Mobile: +46-708-55 86 90