SQL data type is an attribute that specifies type of data of any object. Each column, variable and expression has related data type in SQL.
You would use these data types while creating your tables. You would choose a particular data type for a table column based on your requirement.
SQL Server offers six categories of data types for your use:
Exact Numeric Data Types:
DATA TYPE
|
FROM
|
TO
|
Bigint
|
-9,223,372,036,854,775,808
|
9,223,372,036,854,775,807
|
Int
|
-2,147,483,648
|
2,147,483,647
|
Smallint
|
-32,768
|
32,767
|
Tinyint
|
0
|
255
|
bit
|
0
|
1
|
decimal
|
-10^38 +1
|
10^38 -1
|
numeric
|
-10^38 +1
|
10^38 -1
|
money
|
-922,337,203,685,477.5808
|
+922,337,203,685,477.5807
|
smallmoney
|
-214,748.3648
|
+214,748.3647
|
Approximate Numeric Data Types:
DATA TYPE
|
FROM
|
TO
|
float
|
-1.79E + 308
|
1.79E + 308
|
real
|
-3.40E + 38
|
3.40E + 38
|
Date and Time Data Types:
DATA TYPE
|
FROM
|
TO
|
datetime
|
Jan 1, 1753
|
Dec 31, 9999
|
smalldatetime
|
Jan 1, 1900
|
Jun 6, 2079
|
date
|
Stores a date like June 30, 1991
| |
time
|
Stores a time of day like 12:30 P.M.
| |
Note: Here, datetime has 3.33 milliseconds accuracy where as smalldatetime has 1 minute accuracy.
Character Strings Data Types:
DATA TYPE
|
FROM
|
TO
|
char
|
char
|
Maximum length of 8,000 characters.( Fixed length non-Unicode characters)
|
varchar
|
varchar
|
Maximum of 8,000 characters.(Variable-length non-Unicode data).
|
varchar(max)
|
varchar(max)
|
Maximum length of 231characters, Variable-length non-Unicode data (SQL Server 2005 only).
|
text
|
text
|
Variable-length non-Unicode data with a maximum length of 2,147,483,647 characters.
|
Unicode Character Strings Data Types:
DATA TYPE
|
Description
|
nchar
|
Maximum length of 4,000 characters.( Fixed length Unicode)
|
nvarchar
|
Maximum length of 4,000 characters.(Variable length Unicode)
|
nvarchar(max)
|
Maximum length of 231characters (SQL Server 2005 only).( Variable length Unicode)
|
ntext
|
Maximum length of 1,073,741,823 characters. ( Variable length Unicode )
|
Binary Data Types:
DATA TYPE
|
Description
|
binary
|
Maximum length of 8,000 bytes(Fixed-length binary data )
|
varbinary
|
Maximum length of 8,000 bytes.(Variable length binary data)
|
varbinary(max)
|
Maximum length of 231 bytes (SQL Server 2005 only). ( Variable length Binary data)
|
image
|
Maximum length of 2,147,483,647 bytes. ( Variable length Binary Data)
|
Misc Data Types:
DATA TYPE
|
Description
|
sql_variant
|
Stores values of various SQL Server-supported data types, except text, ntext, and timestamp.
|
timestamp
|
Stores a database-wide unique number that gets updated every time a row gets updated
|
uniqueidentifier
|
Stores a globally unique identifier (GUID)
|
xml
|
Stores XML data. You can store xml instances in a column or a variable (SQL Server 2005 only).
|
cursor
|
Reference to a cursor object
|
table
|
Stores a result set for later processing
|