The CREATE TABLE statement and ALTER TABLE statement can specify many different attributes for a table. Along with the basic table structure (number, name and data type of columns, name and location of the table), you can specify other features that allow control over data integrity.
WARNING! Altering tables can interfere with other users of the database. Although you can execute ALTER TABLE statements while other connections are active, you cannot execute them if any other connection is using the table to be altered. For large tables, ALTER TABLE can be a time-consuming operation, and no other requests referencing the table being altered are allowed while the statement is being processed.
This section describes how to use constraints to help ensure that the data entered in the table is correct, and to provide information to Sybase IQ that boosts performance.
