ORACLE modifies the use of ALTER CONSTAINTS in the table structure
- 2021-12-11 19:23:03
- OfStack
1. Create a federated primary key
ALTER TABLE table name ADD CONSTRAINTS end name PRIMARY KEY (column name, column name..);
2. Add characters
ALTER TABLE table name ADD (COLUMN DATATYPE [DEFAULT VALUE] [NULL/NOT NULL]);
3. Delete columns
ALTER TABLE table name DROP (COLUMN) J;
4. Modify the characters of the table
ALTER TABLE Table Name MODIFY (COLUMN DATATYPE [DEFAULT VALUE] [NULL/NOT NULL])