SQL Server Data Types Explained for Beginners


In SQL Server, data types define the type of data that a column can hold. Understanding data types is crucial for designing and working with a database. In this beginner's guide, we'll explain the most common SQL Server data types and how to use them effectively.


Character Data Types

Character data types are used to store text and character-based data. The most common character data types in SQL Server are:


  • CHAR(n): Fixed-length character strings with a specified length (n).
  • VARCHAR(n): Variable-length character strings with a maximum length of (n).
  • TEXT: Stores large amounts of character data (up to 2 GB).

Numeric Data Types

Numeric data types are used for storing numeric values. Some common numeric data types include:


  • INT: Stores whole numbers (integer values).
  • FLOAT: Stores floating-point numbers (real numbers).
  • DECIMAL(p, s): Stores fixed-point numbers with a specified precision (p) and scale (s).

Date and Time Data Types

Date and time data types are used for storing date and time values. The primary date and time data types are:


  • DATE: Stores date values (year, month, day).
  • DATETIME: Stores date and time values with fractions of a second.
  • TIME: Stores time values (hours, minutes, seconds, fractions of a second).

Sample SQL Code for Creating a Table with Data Types

Here's an example of SQL code to create a table that uses some of these data types:


CREATE TABLE Employee (
    EmployeeID INT,
    FirstName VARCHAR(50),
    LastName VARCHAR(50),
    BirthDate DATE,
    Salary DECIMAL(10, 2)
);

This SQL code creates a table named "Employee" with columns for storing employee information, including an integer ID, first name, last name, birthdate, and salary with two decimal places.


What's Next?

You've learned about some of the common SQL Server data types and how to use them in creating tables. As you delve deeper into database design and querying, you'll encounter more data types and scenarios where choosing the right data type is critical for data integrity and performance.


Stay curious and keep exploring SQL Server data types to become proficient in database development and management.