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Integer:

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Bit - 1 bit

Tinyint - 1 byte

Smallint - 2 bytes

Int - 4 bytes

Bigint - 8 bytes

Float:

Float

Real

Text:

Non unicode string: A character occupies 1 byte

Char

Varchar

Text

Unicode string: A character occupies 2 bytes

Nchar

Nvarchar

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create table Student

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(

sid int,

sname varchar(20)

)

Drop table student;

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Add new column:

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Alter table test add grade char(1);

Modify a column data type:

Alter table test alter column grade varchar(10);

Delete a column:

Alter table test drop column grade;

A table can have only one clustered index and any number of non clustered

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index (upto 249)

Unique index – When a unique index exists, the Database Engine checks for duplicate values each time data is added by a insert operations. Insert operations that would generate duplicate key values are rolled back, and the Database Engine displays an error message.

Clustered index - clustered index can be rebuilt or reorganized on demand to control table fragmentation. A clustered index can also be created on a view. This improves the performance.

Non clustered index - Creates an index that specifies the logical ordering of a table. With a nonclustered index, the physical order of the data rows is independent of their indexed order.

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insert into Student values(1,'Ramu')

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insert into Student(sid,sname) values(6,'Raj')

insert into Student(sid) values(2)

insert into Student(sname) values('Seetha')

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update student

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set sid=3

This will set sid =3 for all students

update student

set sid=1

where sname='Ramu‘

This will set sid as 1 only for Ramu

update student

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set sid=3

This will set sid =3 for all students

update student

set sid=1

where sname='Ramu‘

This will set sid as 1 only for Ramu

delete from student

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where sid between 1 and 3

This will delete students with sid 1,2,3

To execute a statement in MS SQL, Select the statement and Click on the

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Execute button in the query analyser or press F5

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The TOP clause can be very useful on large tables with thousands of records.

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Returning a large number of records can impact on performance.

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To select distinct rows, we need to use the distinct key word

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Select distinct name from orders;

Orders

--------

Id Name

-- -------

1 Ram

2 Krish

3 Ram

4 Raj

Will fetch

Ram

Krish

Raj

Select count(name) from orders; will yield the result as 4

Related rows can be grouped together by GROUP BY clause by specifying a

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column as a grouping column.

GROUP BY is associated with an aggregate function

Example: For each part supplied get the part number and the total shipment quantity

Example: SELECT PNO, SUM(QTY) FROM SP GROUP BY PNO

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