Data Type on MS SQL Server

Prepared by-Madhurima

Das (M.Sc. In Computer Science)

Blog URL : http://techgig.info

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What is Data Type?

▪ A data type is an attribute that specifies the type of data. It may be integer type, decimal type, character type, date and time type etc.

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SQL Server Data type

▪ In SQL Server, each column, local variable, expression, and parameter has a related data type.

▪ SQL Server supplies a set of system data types that define all the types of data that can be used with SQL Server.

▪ You can also define your own data types in Transact-SQL or the Microsoft .NET Framework. Alias data types are based on the system-supplied data types.

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Data Type Categories

▪ Data types in SQL Server are organized into the following categories:

Exact NumericsApproximate NumericsDate and TimeCharacter StringsUnicode Character StringsBinaryOther Data Types

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SQL Exact Numeric Data Types

Data Type Storage Capacity

Range

Bigint 8 bytes –263 to 263–1

Int 4 bytes –231 to 231– 1

Smallint 2 bytes –215 to 215– 1

Tinyint 1 bytes 0 to 255

Bit 1 bit 1 or 0

Decimal(p,s) 19 bytes –1038+1 to 1038–1

Numeric(p,s) Same as decimal Same as decimal

Money 8 bytes –263 to 263–1

Smallmoney 4 bytes –231 to 231– 1

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SQL Approximate Numeric Data Types

Data Type Storage Capacity

Range

Float 8 bytes –1.79E +308 to 1.79E+308

Real 4 bytes –3.40E+38 to 3.40E+38

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SQL Date and Time Data Types

Data Type Storage Capacity

Range

Date 3 bytes 0001-01-01 to 9999-12-31

Time 5 bytes 00:00:00.0000000 to 23:59:59.9999999

Datetime 8 bytes January 1, 1753, to December 31, 9999(for Date) & 00:00:00 to 23:59:59.997(for Time)

Smalldatetime 4 bytes 1900-01-01 to 2079-06-06(for Date) & 00:00:00 to 23:59:59(for Time)

Datetime2 Varies 0001-01-01 to 9999-12-31(for Date) & 00:00:00 to 23:59:59.9999999(for Time)

Datetimeoffset 10 bytes Same as Datetime2 with time zone offset range -14:00 to +14:00

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SQL Character String Data Types

Data Type Storage Capacity

Range

Char [(n) ] Varies 1 to 8,000 characters

Varchar [(n|max)] Varies 8,000 characters

Text Varies 231–1 (2,147,483,647) characters

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SQL Unicode Character String Data Types

Data Type Storage Capacity

Range

nchar [(n)] Varies 1 to 4,000 characters

nvarchar [(n|max)] Varies 4,000 characters

ntext Varies 230–1 (1,073,741,823) characters

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SQL Binary Data Types

Data Type Storage Capacity

Range

binary [(n)] Varies 8,000 bytes

varbinary [(n|max)] Varies 8,000 bytes

Image Varies 231–1 (2,147,483,647) bytes

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SQL Other Data Types

▪ Cursor

▪ Hierarchyid

▪ Sql_variant

▪ Table

▪ Timestamp

▪ Uniqueidentifier

▪ Xml

▪ Spatial Types–Geography–Geometry

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SQL User Define Data Types

▪ User define data type are based on system data type of MS SQL Server.

▪ It is created when several table object use the same data in terms of data type, length and null ability.

The syntax of creating user define data types are mentioned bellow :

sp_addtype [ @typename = ] type,            [ @phystype = ] system_data_type            [ , [ @nulltype = ] 'null_type' ]            [ , [ @owner = ] 'owner_name' ]

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Data Type Example

-- Creating User define data type EXEC sp_addtype @typename='Postal_Code',                 @phystype='Varchar(7)',                 @nulltype='NOT NULL' GO                -- Using System data type & User define data type CREATE TABLE emp_address             (Emp_name    VARCHAR(50) NOT NULL,              Postal_code Postal_Code); GO

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Data Type Conversion

▪ Implicit Conversion– Implicit conversions are not visible to the user. – SQL Server automatically converts the data from one

data type to another.

▪ Explicit Conversion– Explicit conversions use the CAST or CONVERT

functions.

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Data Type Precedence

▪ When an operator combines two expressions of different data types, the rules for data type precedence specify that the data type with the lower precedence is converted to the data type with the higher precedence.

▪ If the conversion is not a supported implicit conversion, an error is returned. When both operand expressions have the same data type, the result of the operation has that data type.

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Data Type Precedence

• SQL Server uses the following precedence order for data types:

1. user-defined data types (highest)

2. sql_variant

3. xml

4. datetimeoffset

5. datetime2

6. datetime

7. smalldatetime

8. date

9. time

10. float

11. real

12. decimal

13. money

14. smallmoney

15. bigint

16. int

17. smallint

18. tinyint

19. bit

20. ntext

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21. image

22. timestamp

23. text

24. uniqueidentifier

25. nvarchar (including nvarchar(max) )

26. Nchar

27. varchar (including varchar(max) )

28. char

29. varbinary (including varbinary(max) )

30. binary (lowest)

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Questions ?

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Thank You !