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. , .




ALTER TABLE {ADD {COLUMN [()] [NOT NULL] [CONSTRAINT ] |
ALTER COLUMN [()] |
CONSTRAINT } |
DROP {COLUMN I CONSTRAINT } }

ALTER TABLE:

.
, . , .
.
( ).
. CONSTRAINT.
, . CONSTRAINT.
, .

ALTER TABLE . :

  • ADD COLUMN. , ( ) . , 25 :
  • ALTER TABLE ADD COLUMN TEXT(25)
  • , . CONSTRAINT.
  • NOT NULL, .
  • ALTER COLUMN. , ( ) . , ( INTEGER), 10 :
  • ALTER TABLE ALTER COLUMN TEXT(10)
  • ADD CONSTRAINT. CONSTRAINT.
  • DROP COLUMN. .
  • DROP CONSTRAINT. , CONSTRAINT.

.

if exists(SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = 'STUDENT' and CONSTRAINT_NAME = 'chk_recordbook_num')

Alter table STUDENT drop constraint chk_recordbook_num


. , . .

DROP {TABLE | INDEX ON | PROCEDURE | VIEW }

DROP:

, .
.
.
, .

 

, .

, ALTER TABLE.

CREATE TABLE, - CREATE INDEX ALTER TABLE. , ALTER TABLE.

DROP TABLE PERSONS






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