Identity column , Database view ,Alter query ,

 Indentity columns :-

It Increases the  data value automatically .

 

TABLE CREATION QUERY :-

CREATE TABLE DEMO1 (ID INT IDENTITY(1,1) , NAME VARCHAR(50) );

INSERT INTO DEMO1 (NAME) VALUES ('BABUBHAIYA');

INSERT INTO DEMO1(NAME) VALUES ('RAJU');

INSERT INTO DEMO1(NAME) VALUES ('SHAM');

SELECT * FROM DEMO1;

Q. HOW TO RESET THE IDENTITY TABLE USING TRUNCATE ?

ANS - SYNTAX :-

TRUNCATE TABLE TABLENAME;

EX :- INSERT INTO DEMO1 (NAME) VALUES ('BABU BHAIYA'),('RAJU'),('SHAM');

SELECT * FROM DEMO1

 

l HOW TO CREATE NOT NULL COLUMN?

EX:-CREATE TABLE DEMO2(ID INT NOT NULL, NAME VARCHAR (50))

INSERT INTO DEMO2 VALUES (1,'SALMAN KHAN '),(2, 'ASHWARIYA RAI'),(3,'KATRINA KAF '),(4,'VICKY KAUSHAL');

 

Ø DATABASE VIEW :-

1. View in database is called virtual table.

2. View is used to store  query result .

Ø View operation:-

1. Create view

2. Update view

3. Delete view

4. Display view

 

1. Create view :- syntax:-

Create view name AS QUERY;

Ex :-CREATE VIEW MY AS SELECT * FROM newstudent;

SELECT * FROM my;

 

2. Update view:-

Syntax

Alter view viewname AS  query;

EX- ALTER VIEW MY AS SELECT * FROM newstudent  WHERE roll=202; 

SELECT * FROM MY;

 

3. DELETE VIEW :- SYNTAX:-

DROP VIEW NAME;

EX:-DROP VIEW MY;

 

l  HOW TO DROP TABLE?

ANS SYNTAX:- DROP TABLE NAME;

DROP TABLE newstudent;

 

l Alter Query :-

1. It is use to modify the structure of table.

2. It is used when we have to add any new column .

l Alter operation :-

1. Add new columns.

2. Remove existing columns .

3. Rename database columns .

4. Change data type of the columns.

 

1. Add new columns:-syntax:-

alter table tablename  ADD columnname datatype.

EX- ALTER TABLE DEMO1 ADD CITY VARCHAR(50);

 

2. REMOVE COLUMNS:- syntax

Alter table tablename drop column columnname;

Ex:-ALTER TABLE DEMO1 DROP COLUMN CITY;

SELECT * FROM DEMO1;

 

 

3. RENAME DATABASE COLUMNS:-

SYNATX :- EXEC SP_RENAME ‘TABLENAME.COLUMNNAME’, ‘NEW COLUMN NAME ’, ‘COLUMN’.

EX-EXEC SP_RENAME 'DEMO1.NAME','FAME','COLUMN'; 

 

 

4.  CHANGE THE DATATYPE OF COLUMNS?

SYNTAX:- ALTER TABLE  TABLENAME ALTER COLUMN COLUMNNAME DATATYPE.

Ex:- ALTER TABLE DEMO1 ALTER COLUMN Fame VARCHAR (100);

SELECT * FROM DEMO1;

 

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