Table constraints versus column constraints

Edward Diener

Delphi Developer

Sun, 06 Mar 2005 00:02:30 GMT

Table constraints versus column constraints

I couldn't get the difference between table constraints and column
constraints from the doc. Anybody care to explain ? It seems as if all
constraints refer to columns so I am confused by the idea of table
constraints.

Edward Diene

Delphi Developer

Sun, 06 Mar 2005 02:43:49 GMT

Re:Table constraints versus column constraints

Quote

"Bill Todd" <b...@notthis.dbginc.com> wrote in message

news:23neou4uhc5b4c9f38hjdmftortopmrric@4ax.com...

Quote

> A column constraint is on that can be declared as part of the
> declaration for the column. A table constraint is declared for the
> table as a whole. You can declare a single field primary key as a
> column constraint but a multi-field primary key must be declared as a
> table constraint.

That makes sense. Evidently table constraints can refer to more than one
column while column constraints can only refer to the column for which the
constraint applies.

Quote

> On Tue, 17 Sep 2002 12:02:30 -0400, "Edward Diener"
> <eddie...@tropicsoft.com> wrote:

> >I couldn't get the difference between table constraints and column
> >constraints from the doc. Anybody care to explain ? It seems as if all
> >constraints refer to columns so I am confused by the idea of table
> >constraints.

Bill Tod

Delphi Developer

Sun, 06 Mar 2005 00:47:43 GMT

Re:Table constraints versus column constraints

A column constraint is on that can be declared as part of the
declaration for the column. A table constraint is declared for the
table as a whole. You can declare a single field primary key as a
column constraint but a multi-field primary key must be declared as a
table constraint.

On Tue, 17 Sep 2002 12:02:30 -0400, "Edward Diener"

Quote

<eddie...@tropicsoft.com> wrote:
>I couldn't get the difference between table constraints and column
>constraints from the doc. Anybody care to explain ? It seems as if all
>constraints refer to columns so I am confused by the idea of table
>constraints.

--
Bill (TeamB)
(TeamB cannot respond to questions received via email)

Bill Tod

Delphi Developer

Sun, 06 Mar 2005 04:40:54 GMT

Re:Table constraints versus column constraints

On Tue, 17 Sep 2002 14:43:49 -0400, "Edward Diener"

Quote

<eddie...@tropicsoft.com> wrote:
>"Bill Todd" <b...@notthis.dbginc.com> wrote in message
>news:23neou4uhc5b4c9f38hjdmftortopmrric@4ax.com...
>> A column constraint is on that can be declared as part of the
>> declaration for the column. A table constraint is declared for the
>> table as a whole. You can declare a single field primary key as a
>> column constraint but a multi-field primary key must be declared as a
>> table constraint.

>That makes sense. Evidently table constraints can refer to more than one
>column while column constraints can only refer to the column for which the
>constraint applies.

Exactly.

Quote

>> On Tue, 17 Sep 2002 12:02:30 -0400, "Edward Diener"
>> <eddie...@tropicsoft.com> wrote:

>> >I couldn't get the difference between table constraints and column
>> >constraints from the doc. Anybody care to explain ? It seems as if all
>> >constraints refer to columns so I am confused by the idea of table
>> >constraints.

--
Bill (TeamB)
(TeamB cannot respond to questions received via email)

Other Threads

1. Constraints and TTable.Constraints

2. Importing Paradox constraints with TTable.Constraints ...

3. Importing Paradox constraints with TTable.Constraints ...

4. Dropping columns with constraints

5. remove constraint "NOT NULL" from column

6. Create constraint in Servers and Paradox tables - HOW?

7. Q: Retrieveing information about a tables referential constraints

8. Table custom constraints - please help!

9. Deleting constraint on temp table...

10. Adding Constraint to SQL Table