SQLDROP Keyword
DROP COLUMN
TheDROP COLUMN command is used to delete a column in an existing table.
The following SQL deletes the "ContactName" column from the "Customers" table:
Example
DROP COLUMN ContactName;
DROP a UNIQUE Constraint
To drop a UNIQUE constraint, use the following SQL:
SQL Server / Oracle / MS Access:
DROP CONSTRAINT UC_Person;
MySQL:
DROP INDEX UC_Person;
DROP a PRIMARY KEY Constraint
To drop a PRIMARY KEY constraint, use the following SQL:
SQL Server / Oracle / MS Access:
DROP CONSTRAINT PK_Person;
MySQL:
DROP PRIMARY KEY;
DROP a FOREIGN KEY Constraint
To drop a FOREIGN KEY constraint, use the following SQL:
SQL Server / Oracle / MS Access:
DROP CONSTRAINT FK_PersonOrder;
MySQL:
DROP FOREIGN KEY FK_PersonOrder;
DROP a CHECK Constraint
To drop a CHECK constraint, use the following SQL:
SQL Server / Oracle / MS Access:
DROP CONSTRAINT CHK_PersonAge;
MySQL:
DROP CHECK CHK_PersonAge;
DROP DEFAULT
TheDROP DEFAULT command is used to delete a DEFAULT constraint.
To drop a DEFAULT constraint, use the following SQL:
SQL Server / Oracle / MS Access:
ALTER COLUMN City DROP DEFAULT;
MySQL:
ALTER City DROP DEFAULT;
DROP INDEX
TheDROP INDEX command is used to delete an index in a table.
MS Access:
SQL Server:
DB2/Oracle:
MySQL:
DROP INDEXindex_name;
DROP DATABASE
TheDROP DATABASE command is used is to delete an existing SQL database.
The following SQL drops a database named "testDB":
Example
Note: Be careful before dropping a database. Deleting a database will result in loss of complete information stored in the database!
DROP TABLE
TheDROP TABLE command deletes a table in the database.
The following SQL deletes the table "Shippers":
Example
Note: Be careful before deleting a table. Deleting a table results in loss of all information stored in the table!
DROP VIEW
TheDROP VIEW command deletes a view.
The following SQL drops the "Brazil Customers" view:
