SQL Anywhere supports domains which allow constraint and default definitions to be encapsulated in the data type definition. It also supports explicit defaults and CHECK conditions in the CREATE TABLE statement. It does not, however, support named defaults.

NULL

SQL Anywhere and Adaptive Server Enterprise differ in some respects in their treatment of NULL. In Adaptive Server Enterprise, NULL is sometimes treated as if it were a value.

For example, a unique index in Adaptive Server Enterprise cannot contain rows that hold null and are otherwise identical. In SQL Anywhere, a unique index can contain such rows.

By default, columns in Adaptive Server Enterprise default to NOT NULL, whereas in SQL Anywhere the default setting is NULL. You can control this setting using the allow_nulls_by_default option. Specify explicitly NULL or NOT NULL to make your data definition statements transferable.

For information about this option, see Setting options for Transact-SQL compatibility.

Temporary tables

You can create a temporary table by placing a pound sign (#) in front of the table name in a CREATE TABLE statement. These temporary tables are SQL Anywhere declared temporary tables, and are available only in the current connection.

Physical placement of a table is performed differently in Adaptive Server Enterprise and in SQL Anywhere. SQL Anywhere supports the ON segment-name clause, but segment-name refers to a SQL Anywhere dbspace.

See also

• Testing SQL compliance using the SQL Flagger
• DECLARE LOCAL TEMPORARY TABLE statement
• CREATE TABLE statement