In SQL, a data type is an attribute that specifies the type of data an object can hold: character data (string data), binary data, integer data, monetary data, date and time data, and so on. Following data types are special SQL data types to store geographical data.
- Geometry Data type: This data type is used to represent the data in a two dimensional Euclidean coordinate system
- Geography Data type: The functionality of this data type is same as the Geometry data type. The only difference between both these data types is, when you declare the variable with Geography data type, you are specifying the points in terms of latitude and longitude.
List of available SQL Data Types
Following are the list of available SQL server Data Types, and their description.
SQL Numeric Data Type
| SQL Data Types | Description | Length |
|---|---|---|
| int | Stores the integer values ranging from -2,147,483,648 to 2,147,483,647 | 4 Bytes |
| tinyint | Stores the integer values ranging from 0 to 255 | 1 Byte |
| smallint | Stores the integer values ranging from -32,768 to 32,767 | 2 Byte |
| bigint | It stores the integer values ranging from -253 to -253 – 1 | 8 Bytes |
| money | It stores the financial values ranging from -922,337,203,685,477.5808 to -922,337,203,685,477.5807 | 8 Bytes |
| smallmoney | It stores the financial values ranging from -214,748.3648 to 214,748.3647 | 4 Bytes |
| decimal(p,s) | It stores the decimal values. Here p is the Precision, s is the Scale, and the maximum precision value is 38 digits. | 5 – 17 Bytes |
| numeric(p,s) | Functionality of this data type is equivalent to decimal (p, s). | 5 – 17 Bytes |
| float(n) | It stores the floating point values with precision of 7 digit (if n = 24, and 15 digit (if n = 53). | 5 – 17 Bytes5 – 17 Bytes If n = 24 it uses 4 Bytes, and If n = 53 it uses 8 Bytes |
| real | Functionality of this data type is equivalent to float(24). | 4 Bytes |
SQL Character and String Data Types
| SQL Data Types | Description | Length |
|---|---|---|
| char(n) | It stores n characters | n Bytes, where range of n is from 1 to 8000 |
| nchar(n) | It stores n Unicode characters | 2n Bytes, where range of n is from 1 to 4000 |
| varchar(n) | It stores approximately n characters | Actual string length + 2 Byte, where range of n is from 1 to 8000 |
| varchar(max) | It stores up to 231-1 characters | Actual string length + 2 Byte |
| nvarchar(n) | It stores approximately n characters | 2n(Actual string length) + 2 Byte, where range of n is from 1 to 8000 |
| nvarchar(max) | It stores up to ((231-1) /2) – 2 characters | 2n(Actual string length) + 2 Byte |
SQL Binary Data Types
| SQL Data Types | Description | Length |
|---|---|---|
| bit | It stores single bit of data | 1 byte for 8-bit column |
| binary(n) | It stores n bytes of binary data | n Bytes, where range of n is from 1 to 8000 |
| varbinary(n) | It stores approximately n bytes of binary data | Actual string length + 2 Byte, where range of n is from 1 to 8000 |
| varbinary(max) | It stores up to 231-1 bytes of binary data | Actual string length + 2 Byte |
SQL Date and Time Data Types
| SQL Data Types | Description | Length | Example |
|---|---|---|---|
| date | It stores dates between January 01, 0001, and December 31, 9999 | 3 Bytes | 2016-08-19 |
| datetime | It stores date and time between January 01, 1753, and December 31, 9999 | 8 Bytes | 2016-08-19 10:15:45.0110 |
| datetime2 | It stores date and time between January 01, 0001, and December 31, 9999 | 6 – 8 Bytes | 2016-08-19 10:15:45.0110112 |
| datetimeoffset | It is same as datetime2, and in addition it will include the Universal Time Coordinate (UTC) offset (we also called as GMT) | 8 – 10 Bytes | 2016-08-19 10:15:45.0110112 +05:30 |
| smalldatetime | It stores date and time between January 01, 1990, and June 06, 2079 | 4 Bytes | 2016-08-19 |
| time | It stores time with an accuracy of 100 nano Seconds. The time range is between 00:00:00.0000000, and 23:59:59.9999999 | 3 – 5 Bytes | 10:15:45.0110136 |
Difference between Char and Varchar, Nvarchar data types
Char Data Type
Character or Char data type is used to store the fixed length of characters. For example, if we declare variable, @str CHAR (50) means it will allocate memory for 50 characters. Suppose we inserted 10 characters into @str variable, 10 characters of memory will be used, and the remaining 40 characters will be wasted.
Varchar Data Type
Varchar data type means variable character, and it is used to store the non-Unicode characters. Varchar allocates the memory based on the number of characters inserted into it. For example if we declare variable, @name VARCHAR (50) means, it will allocate memory for 0 characters. Suppose we inserted 10 characters into @name variable then, it will allocate the memory to store those 10 characters (it allocate literally 10 characters, and no wastage). If you think that the size of the column data might exceed 8000 bytes, please use Varchar(max).
NVarchar Data Types
NVarchar data type is same as Varchar data type. The only difference between them is, it is used to store Unicode characters. NVarchar data type will take double (2n) space to store the other language characters. If you think that the size of the column data might exceed 4000 bytes, please use nvarchar(max).
NOTE: When you are not storing other language characters then, I suggest you to choose Varchar
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