Defining Columns

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When you create a table in the database, your main task is to define the various attributes and constraints for each of the columns in the table. The syntax for defining a column is:

<col_def> = col {datatype
| COMPUTED [BY] (<expr>)
| domain}
 [DEFAULT {literal | NULL | USER}]
 [NOT NULL] [<col_constraint>]
 [COLLATE collation]

The next sections list the required and optional attributes that you can define for a column.

Topics

• Required Attributes
• Optional Attributes
• Specifying the Data Type
• Casting Data Types
• Defining a Character Set
• The COLLATE Clause
• Defining Domain-based Columns
• Defining Expression-based Columns
• Specifying Column Default Values
• Specifying NOT NULL Columns