SQL Commands

Question 1

SELECT

Answer 1

Retrieves data

SELECT * FROM Product;

Question 2

INSERT

Answer 2

INSERT INTO Product
VALUES ();

Question 3

UPDATE

Answer 3

Updates existing table.

UPDATE TABLE SET VendorName = ‘ ‘
WHERE vendorID = ‘ ‘;

Question 4

DELETE

Answer 4

Removes records

DELETE FROM Customers
WHERE customerID = 10;

Question 5

CRÉATE

Answer 5

Creates a database, table, index, function or view.

CREATE TABLE Vendor
(
vendorID VARCHAR2(5)
);

Question 6

ALTER

Answer 6

Alters the structure.

ALTER TABLE Product
ADD (reorderLevel NUMBER(3) DEFAULT 10;

Question 7

DROP

Answer 7

Deletes objects;

DROP TABLE Vendor;

Question 8

COMMIT

Answer 8

Saves all changes made during the transaction.

COMMIT;

Question 9

ROLLBACK

Answer 9

Undoes all changes made.

ROLLBACK;

Question 10

GRANT

Answer 10

Assigns new privileges to a user account, allowing access to specific database objects, actions or functions.

GRANT SELECT,
UPDATE ON Employees
TO user1;

Question 11

REVOKE

Answer 11

Removed previously granted permissions.

REVOKE UPDATE,
ON Employees
FROM user1;

Question 12

CREATE TABLE

Answer 12

CREATE TABLE table_name;

Question 13

ALTER TABLE

Answer 13

ALTER TABLE table_name;

Question 14

MODIFY

Answer 14

Changes attribute characteristics.

ALTER TABLE Product
MODIFY( P_price decimal 9,2);

Question 15

ADD

Answer 15

add new attribute.

ALTER TABLE Product
ADD ( P_Reorder_Qty number(2)
P_Reorder char (1) DEFAULT);

Question 16

DROP TABLE

Answer 16

Remove table.

DROP TABLE table_name;

Question 17

CRÉATE INDEX

Answer 17

Improve efficiency on frequent data searches.

CREATE INDEX P_Code
ON Product(PCode);

Question 18

CREATE UNIQUE INDEX

Answer 18

Prevents a duplicate from being created.

CRÉATE UNIQUE INDEX P_CodeX
ON Product (PCode);

Question 19

DROP INDEX

Answer 19

Delete index.

DROP INDEX P_CodeX;