Altering a Table

Go Up to Altering Metadata

ALTER TABLE enables the following changes to an existing table:

• Adding new column definitions
• Adding new table constraints
• Dropping existing column definitions
• Dropping existing table constraints
• Changing column definitions by dropping existing definitions, and adding new ones
• Changing existing table constraints by dropping existing definitions, and adding new ones
• Modifying column names and data types

The simple syntax of ALTER TABLE is as follows:

EXEC SQL
ALTER TABLE name {ADD colname <data_type> [NOT NULL]
| ALTER [COLUMN] simple_column_name alter_rel_field

 | DROP colname | ADD CONSTRAINT constraintname tableconstraint
| DROP CONSTRAINT constraintname};

Note:
For information about adding, dropping, and modifying constraints at the table level, see the Data Definition Guide.

For the complete syntax of ALTER TABLE, see the Language Reference Guide.

Topics

• Adding a New Column to a Table
• Dropping an Existing Column
• Modifying a Column

Advance To:

• Adding a New Column to a Table (Embedded SQL Guide)