--Add, modify, and delete constraints--1. Add Constraint ALTER TABLE tableAdd[constraint constraint]Constraint_type (column1[, Column2,...])[constraint_parameters];Alter TableBooks Modify Title not NULL;--add a non-null constraint--2. Modifying ConstraintsALTER TABLE TableMODIFY[CONSTRAINT CONSTRAINT][PRIMARY KEY]|[UNIQUE (column1[,column2,...])][constraint_parameters];--3. Renaming a constraintAlter Table TableRenameconstraintOld_name tonew_name;--4. Delete a constraintALTER TABLE Table DROP[CONSTRAINT CONSTRAINT] [PRIMARY KEY]|[UNIQUE (column1[,column2,...])] [CASCADE][keep| DROP INDEX]SetConstraints AllDeferred--delay checking for all constraints that can be deferredSetConstraints AllImmediate--Restore all delay check constraints for immediate check--Query Constraint InformationAll_constraints--contains all constraint definition information that the current user can accessUser_constraints--contains definition information for all constraints owned by the current userDba_constraints--contains the definition information for all constraints in the current databaseAll_cons_columns--contains constraint column information that the current user can accessUser_cons_columns--contains information about constraint columns that are owned by the current userDba_cons_columns--contains information about all constraint columns for the current database
Oracle Database Maintenance Operations 4