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SQL Anywhere 10.0.1 » SQL Anywhere Server - SQL Usage » Ensuring Data Integrity

SQL statements for implementing integrity constraints Next Page

Using column defaults

Column defaults automatically assign a specified value to a particular column whenever someone enters a new row into a database table. The default value assigned requires no action on the part of the client application, however if the client application does specify a value for the column, the new value overrides the column default value.

Column defaults can quickly and automatically fill columns with information, such as the date or time a row is inserted, or the user ID of the person entering the information. Using column defaults encourages data integrity, but does not enforce it. Client applications can always override defaults.

Supported default values

SQL supports the following default values:

Creating column defaults
Altering and dropping column defaults
Working with column defaults in Sybase Central
Current date and time defaults
The user ID defaults
The NEWID default
The NULL default
String and number defaults
Constant expression defaults