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 <datatype> [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.