Difference between revisions of "PRIMARY KEY Column Constraint"

Revision as of 17:18, 8 December 2009

Purpose

Column constraint to define table's Primary Key

Syntax

PRIMARY KEY [COLLATE <cCollateSequence>]

See Also

ALTER TABLE, CONSTRAINTS, CREATE TABLE

Description

A constraint is used to define rules that help to provide data integrity. Column constraints are specific to the column name specified. You must have ALTER privilege on the table. The table will be locked for EXCLUSIVE use during the operation.

The PRIMARY KEY column constraint is used to define the column as the table's Primary Key. A unique tag index is built on the specified column; it is given the same name as the column. If a table already has a primary key defined, an error will be returned.

The optional COLLATE <cCollateSequence> clause is included for Visual FoxPro language compatibility only.

Example

set sql to vfp
CREATE TABLE newcust (acc_ref char(5) default strzero(seqno(),5) PRIMARY KEY, ;
acc_name char(20))
list structure index

Products

Recital, Recital Server