ALTER table statement (2)

Modifying a Column

ALTER    TABLE        dept80 MODIFY        (last_name VARCHAR2(30));

 

• The width or precision of a numeric column
• The width of numeric or character columns
• Decrease the width of a column if:
  - contains only null value
  - The table has no rows
  - the decrease in column width is not less than the existing values in that column.
  
• Data type (if contains null values)
  exception : Char to VARCHAR2 (when it has null values)
  
• Default Values

 

Dropping a Column

ALTER TABLE        dept80 DROP COLUMN    job_id;

 

- The partitioning key of a partitioned table or column can't be dropped.