Hello Dev, welcome to the world of SQL Server data types. In this journal article, we will be discussing the different data types available in SQL Server, their usage, and their limitations. Data types play a vital role in database management and affect the performance of a database. So, let’s dive in and explore the different data types in SQL Server.
Introduction to Data Types
Data types are a way of specifying the type of values that are stored in tables, variables or expressions in SQL Server. Each data type has specific storage requirements, range of values it can hold, and operations that can be performed on it. In SQL Server, data types are classified into two categories: built-in data types and user-defined data types.
Built-in Data Types
Built-in data types are the ones that come pre-defined with SQL Server. These data types are classified into four categories:
Category |
Description |
Examples |
|---|---|---|
Numeric |
Data types that store numeric values |
int, decimal, float, money, smallmoney |
Character Strings |
Data types that store textual data |
char, varchar, text |
Date/Time |
Data types that store date and time values |
date, datetime, smalldatetime |
Binary Strings |
Data types that store binary data |
binary, varbinary, image |
User-Defined Data Types
User-defined data types are the ones that are created by the user. These data types are based on the built-in data types and allow the user to define their own data types based on their specific requirements.
Numeric Data Types
Numeric data types are used to store numeric values such as integers, decimals, and floating-point values. Numeric data types are further divided into four categories:
Integer Data Types
Integer data types are used to store whole numbers. The following table shows the different integer data types available in SQL Server:
Data Type |
Description |
Range |
|---|---|---|
tinyint |
Stores integers from 0 to 255 |
0 to 255 |
smallint |
Stores integers from -32,768 to 32,767 |
-32,768 to 32,767 |
int |
Stores integers from -2,147,483,648 to 2,147,483,647 |
-2,147,483,648 to 2,147,483,647 |
bigint |
Stores integers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
Decimal Data Types
Decimal data types are used to store decimal values. The following table shows the different decimal data types available in SQL Server:
Data Type |
Description |
Storage Size |
|---|---|---|
decimal(p, s) |
Stores decimal values with precision p and scale s |
5 to 17 bytes |
numeric(p, s) |
Stores decimal values with precision p and scale s |
5 to 17 bytes |
money |
Stores currency values from -922,337,203,685,477.5808 to +922,337,203,685,477.5807 |
8 bytes |
smallmoney |
Stores currency values from -214,748.3648 to +214,748.3647 |
4 bytes |
Floating-Point Data Types
Floating-point data types are used to store decimal values with a high degree of precision. The following table shows the different floating-point data types available in SQL Server:
Data Type |
Description |
Storage Size |
|---|---|---|
float(n) |
Stores floating-point values with a precision of up to 15 digits |
4 or 8 bytes |
real |
Stores floating-point values with a precision of up to 7 digits |
4 bytes |
Bit Data Type
The bit data type is used to store a single binary value of either 0 or 1. The following table shows the different bit data types available in SQL Server:
Data Type |
Description |
|---|---|
bit |
Stores a single binary value of either 0 or 1 |
Character Data Types
Character data types are used to store textual data. The following table shows the different character data types available in SQL Server:
Fixed-Length Character Data Types
Fixed-length character data types are used to store strings with a fixed length. The following table shows the different fixed-length character data types available in SQL Server:
Data Type |
Description |
Storage Size |
|---|---|---|
char(n) |
Stores strings with a fixed length of n characters |
n bytes |
binary(n) |
Stores binary data with a fixed length of n bytes |
n bytes |
Variable-Length Character Data Types
Variable-length character data types are used to store strings with a variable length. The following table shows the different variable-length character data types available in SQL Server:
Data Type |
Description |
Storage Size |
|---|---|---|
varchar(n) |
Stores strings with a maximum length of n characters |
1 to n bytes |
varbinary(n) |
Stores binary data with a maximum length of n bytes |
1 to n bytes |
text |
Stores large variable-length character data |
2^31-1 bytes |
ntext |
Stores Unicode character data with a maximum length of 1,073,741,823 characters |
2^31-1 bytes |
Date/Time Data Types
Date/time data types are used to store date and time values. The following table shows the different date/time data types available in SQL Server:
Date/Time Data Types
Date/time data types are used to store date and time values. The following table shows the different date/time data types available in SQL Server:
Data Type |
Description |
Range |
|---|---|---|
date |
Stores a date value |
0001-01-01 to 9999-12-31 |
time |
Stores a time value |
00:00:00.0000000 to 23:59:59.9999999 |
datetime |
Stores a date and time value with a precision of 3.33 milliseconds |
1753-01-01 to 9999-12-31 |
smalldatetime |
Stores a date and time value with a precision of 1 minute |
1900-01-01 to 2079-06-06 |
datetime2(p) |
Stores a date and time value with a precision of up to p digits, where p can be from 0 to 7 |
0001-01-01 to 9999-12-31 |
datetimeoffset(p) |
Stores a date and time value with time zone offset with a precision of up to p digits, where p can be from 0 to 7 |
0001-01-01 to 9999-12-31 |
FAQs
1. What is the difference between char and varchar data types?
The char data type is used to store fixed-length strings, whereas the varchar data type is used to store variable-length strings.
2. How do I choose the right data type for my database?
The choice of data type depends on the type of data you want to store and the operations you want to perform on them. It’s important to choose the right data type to ensure optimal performance and storage efficiency.
3. Can I create my own data type in SQL Server?
Yes, you can create your own data type in SQL Server using the user-defined data type feature.
4. What is the difference between datetime and smalldatetime data types?
The datetime data type stores date and time values with a precision of 3.33 milliseconds, whereas the smalldatetime data type stores date and time values with a precision of 1 minute.
5. What is the maximum size of the text data type?
The text data type can store up to 2^31-1 bytes of data.
Conclusion
In conclusion, data types play a critical role in SQL Server database management. Choosing the right data type can have a significant impact on database performance and storage efficiency. In this article, we have discussed the different data types available in SQL Server, their usage, and their limitations. We hope this has helped you gain a better understanding of data types in SQL Server.