Jan 5, 2015

SELECT, INSERT, DELETE and UPDATE Statements in SQL Server

SELECT 
Select statement use to retrieve data from table, the result is store in result table called Result-Set.
Syntax:
SELECT <column's name> FROM <Table Name>
Example:
IF OBJECT_ID('dbo.Employee', 'U') IS NOT NULL
       DROP TABLE Employee
CREATE TABLE Employee
(
       ID INT IDENTITY(1,1),
       FNAME VARCHAR(50),
       LNAME VARCHAR(50),
       ADDRESS VARCHAR(1000),
       CREATEDDATE DATETIME
)
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('DILIP','SINGH','DELHI',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('VIPUL','BHATT','NOIDA',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('RAJ','SINGH','BOKARO',GETDATE())
First run above code, it will create table "Employee" and also will insert  three records in table.
Select Statement
SELECT * FROM Employee
Above query will return all the columns in result-set.
Result







Select statement with column name
SELECT FNAME,LNAME,ADDRESS FROM Employee
It will return column 'FNAME','LNAME','ADDRESS' in result-set.

Result







INSERT
Insert statement use for insert new records into table.
Syntax:
INSERT INTO <table name> VALUES <values>
Example:
IF OBJECT_ID('dbo.Employee', 'U') IS NOT NULL
       DROP TABLE Employee
CREATE TABLE Employee
(
       ID INT IDENTITY(1,1),
       FNAME VARCHAR(50),
       LNAME VARCHAR(50),
       ADDRESS VARCHAR(1000),
       CREATEDDATE DATETIME
)
Run above query then select statement as bellow.
SELECT * FROM Employee
You will find no records
Insert Statements
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('DILIP','SINGH','DELHI',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('VIPUL','BHATT','NOIDA',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('RAJ','SINGH','BOKARO',GETDATE())
Again run select statement.
SELECT * FROM Employee
Result







DELETE
Delete statement use to delete records from table.
Syntax:
DELETE FROM <table name> WHERE <condition>
Example:
IF OBJECT_ID('dbo.Employee', 'U') IS NOT NULL
       DROP TABLE Employee
CREATE TABLE Employee
(
       ID INT IDENTITY(1,1),
       FNAME VARCHAR(50),
       LNAME VARCHAR(50),
       ADDRESS VARCHAR(1000),
       CREATEDDATE DATETIME
)
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('DILIP','SINGH','DELHI',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('VIPUL','BHATT','NOIDA',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('RAJ','SINGH','BOKARO',GETDATE())
Run above query then select statement

SELECT * FROM Employee
 Result







Delete Statement
DELETE FROM Employee
Note: this query will delete all records of table

Delete records with condition, where clause use for condition
DELETE FROM Employee WHERE FNAME='DILIP'
Now run select statement
SELECT * FROM Employee
Result







Above result set show, the row which FNAME is DILIP has been deleted from table.

UPDATE
Update statement use to update particular column record in table.
Syntax:
UPDATE <table name> SET <column name> WHERE <condition>
Example:
IF OBJECT_ID('dbo.Employee', 'U') IS NOT NULL
       DROP TABLE Employee
CREATE TABLE Employee
(
       ID INT IDENTITY(1,1),
       FNAME VARCHAR(50),
       LNAME VARCHAR(50),
       ADDRESS VARCHAR(1000),
       CREATEDDATE DATETIME
)
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE)
 VALUES('DILIP','SINGH','DELHI',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('VIPUL','BHATT','NOIDA',GETDATE())
INSERT INTO Employee (FNAME,LNAME,ADDRESS,CREATEDDATE) VALUES('RAJ','SINGH','BOKARO',GETDATE())
Run above query then select statement 

Result







Update Statement
UPDATE Employee SET ADDRESS='GORAKHPUR' 
It will update ADDRESS column with 'GORKHPUR' of all table row.
Run select statement
SELECT * FROM Employee
Result







Update Statement with  condition
UPDATE Employee SET ADDRESS='GORAKHPUR' WHERE FNAME='DILIP'
run select statement
SELECT * FROM Employee
Result