Understanding SQL Data Types

When you work with SQL databases, you will often create tables to store data. Each column in a table must have a data type, which tells the database what kind of data that column will hold. Understanding SQL data types is essential for designing efficient databases and avoiding errors.

SQL data types can be broadly categorized into numeric types, character types, date and time types, and more. Numeric types store numbers, character types store text, and date/time types handle dates and times. Choosing the right data type helps keep your data consistent and your queries fast.

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

In the example above, EmployeeID uses INT for integers, FirstName and LastName use VARCHAR for variable-length strings, BirthDate uses DATE for storing dates, and Salary uses DECIMAL to store currency values with two decimal places. Using the correct data types helps prevent errors such as trying to store text in a numeric column.