The various forms of syntax for ALTER TABLE are summarized in Table 4-3 , and described in detail in the following sections.

Table 4-3. ALTER TABLE Syntax

Element

Description

ALTER TABLE table_name 
      ADD [ COLUMN ] 
      column_name column_type

Adds a column named column_name of type column_type to the table called table_name .

ALTER TABLE table_name 
      ALTER [ COLUMN ] 
      column_name 
      { SET DEFAULT value | 
        DROP DEFAULT }

Either sets the default value of value to the column column_name of the table called table_name , or removes an existing default value.

ALTER TABLE table_name 
      RENAME TO new_table_name

Renames the table called table_name to new_table_name .

ALTER TABLE table_name 
      RENAME [ COLUMN ] 
      column_name 
      TO new_column_name

Renames the column column_name within the table called table_name to new_column_name .

ALTER TABLE table_name 
      ADD CONSTRAINT 
      constraint_name 
      constraint_definition

Adds a constraint named constraint_name with the definition of constraint_definition to the table called table_name .

ALTER TABLE table_name 
      OWNER TO new_owner

Changes the ownership of the table called table_name to the user new_owner .