Adding and Deleting database attributes Add,drop,modify

Create a new table: Create table nac_user.a_bt (dept VARCHAR2( 5)); Note: There must be at least one field in the table when you create a new table To delete an entire table: Drop  TableNAC_USER.A_BT; to add a property to a table: alter table nac_user.t_p_merchant add sex char( 1 ) default(' M ')

New FOREIGN KEY properties: ALTER TABLE T_fix_bind_route add constraint fk_t_fix_bi_reference_t_l_term foreign key (Lt_termno, Lt_merchno) References T_l_terminal (Lt_termno, Lt_merchno);

to delete a property of a table: alter table nac_user.t_p_merchant drop (pm_status) to change a property of a table: alter table nac_user.t_p_merchant Modify dept Char( (Original dept char (20)) at this time to ensure that the value of dept under the length of no more than ten)

---- Specify Constraint name disable /activate constraint (disable/ activate constraint causes the operation to Delete and rebuild the index) ALTER TABLE employees disable/  Enable unique Emailalter Table employees disable/enable constraint emp_ename_pkhttp://  Www.codesky.net/article/200911/143229.html

Adding and Deleting database attributes Add,drop,modify