In this tutorial, we’ll explore the different types of data available in SQL and understand why they are important.
Understanding Data Types and Their Importance
With the massive amount of data we work with daily, storing everything in a single type would make handling and organizing it very difficult. Data types help us manage different kinds of information efficiently.
Example: When storing student data, we may need various data types—like using varchar for names, int for roll numbers, and date for the birthdate. This example highlights the importance of choosing the right data type when building a database.
Types of Data in SQL
1. Binary Data Types
These are used for storing binary data:
Type
Description
binary
Fixed-length binary data, up to 8000 bytes.
varbinary
Variable-length binary data, up to 8000 bytes.
varbinary(max)
Variable-length binary data, up to 2^31 bytes.
image
Large binary data, up to 2,147,483,647 bytes.
2. Exact Numeric Data Types
Type
Description
Range
bigint
Large integers
-9,223,372,036,854,775,808 to 9,223,372,036,854,775,808
int
Standard integers
-2,147,483,648 to 2,147,483,648
smallint
Small integers
-32,768 to 32,768
tinyint
Tiny range
0 to 255
bit
Boolean values
0 or 1
decimal
Precise decimal numbers
-10^38+1 to 10^38-1
numeric
Same as decimal
-10^38+1 to 10^38-1
money
Monetary values
-922,337,203,685,477.5808 to 922,337,203,685,477.5808
smallmoney
Smaller monetary values
-214,748.3648 to 214,748.3648
3. Approximate Numeric Data Types
Type
Description
Range
float
Floating-point numbers
-1.79E+308 to 1.79E+308
real
Approximate real numbers
-3.40E+38 to 3.40E+38
4. Character String Data Types
Type
Description
char
Fixed-length characters (up to 8000 characters)
varchar
Variable-length characters (up to 8000 characters)
varchar(max)
Large variable-length text (up to 2^31 characters)
text
Variable-length text (up to 2,147,483,647 characters)
5. Unicode Character String Data Types
Type
Description
nchar
Fixed-length Unicode characters (up to 4000 characters)
nvarchar
Variable-length Unicode characters (up to 4000 characters)
nvarchar(max)
Large Unicode text (up to 2^31 characters)
ntext
Large Unicode text (up to 1 GB)
6. Date and Time Data Types
Type
Description
Range
datetime
Date and time
Jan 1, 1753 to Dec 31, 9999
smalldatetime
Smaller range of date/time
Jan 1, 1753 to Jun 6, 2079
date
Only date values
Unlimited
time
Only time values
Unlimited
year
Year values (2 or 4 digits)
Unlimited
timestamp
Time-related unique values
Unlimited
7. Miscellaneous Data Types
Type
Description
clob
Large text data (up to 2 GB)
blob
Large binary objects
XML
Stores XML formatted data
JSON
Stores JSON formatted data
cursor
Cursor objects used in loops/operations
UUID
Universally unique identifiers
bfile
Binary files stored externally
Summary
This tutorial gave you an overview of the different data types used in SQL. Commonly used ones include int, varchar, date, and boolean.
When defining data types, it's crucial to analyze the kind of data that will go into each column. Once set, only matching data types can be inserted successfully—otherwise, SQL will reject the command.
We’ll continue learning more in the upcoming tutorials.
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