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Using global autoincrement default column values Next Page

Declaring default global autoincrement

You can set default values in your database by selecting the column properties in Sybase Central, or by including the DEFAULT GLOBAL AUTOINCREMENT phrase in a TABLE or ALTER TABLE statement.

Optionally, the partition size can be specified in parentheses immediately following the AUTOINCREMENT keyword. The partition size may be any positive integer, although the partition size is generally chosen so that the supply of numbers within any one partition will rarely, if ever, be exhausted.

For columns of type INT or UNSIGNED INT, the default partition size is 216 = 65536; for columns of other types the default partition size is 232 = 4294967296. Since these defaults may be inappropriate, especially if our column is not of type INT or BIGINT, it is best to specify the partition size explicitly.

For example, the following statement creates a simple table with two columns: an integer that holds a customer identification number and a character string that holds the customer's name.

CREATE TABLE Customers (
   name VARCHAR(128) NOT NULL,

In the above example, the chosen partition size is 5000.

For more information on GLOBAL AUTOINCREMENT, see CREATE TABLE statement.