3-2 SQL Data Types Explained

Key Concepts

• Numeric Data Types
• Character Data Types
• Date and Time Data Types

Numeric Data Types

Numeric data types in SQL are used to store numerical values. These types can be further categorized into integers and floating-point numbers. Common numeric data types include:

• INT: Used for storing whole numbers.
• FLOAT: Used for storing floating-point numbers with decimal places.
• DECIMAL: Used for storing exact decimal numbers with a specified precision.

Example: In a "Products" table, the "Price" column could be of type DECIMAL(10, 2) to store prices with two decimal places.

Character Data Types

Character data types are used to store textual data. These types can store single characters, fixed-length strings, or variable-length strings. Common character data types include:

• CHAR: Used for storing fixed-length strings.
• VARCHAR: Used for storing variable-length strings.
• TEXT: Used for storing large amounts of text data.

Example: In a "Users" table, the "Username" column could be of type VARCHAR(50) to store usernames with a maximum length of 50 characters.

Date and Time Data Types

Date and time data types are used to store temporal values. These types can store dates, times, or both. Common date and time data types include:

• DATE: Used for storing dates in the format YYYY-MM-DD.
• TIME: Used for storing times in the format HH:MM:SS.
• DATETIME: Used for storing both dates and times in the format YYYY-MM-DD HH:MM:SS.

Example: In an "Orders" table, the "OrderDate" column could be of type DATETIME to store both the date and time when an order was placed.

Examples and Analogies

Example: Employee Records

Consider an "Employees" table with columns like "EmployeeID" (INT), "Name" (VARCHAR(100)), and "HireDate" (DATE). This table uses numeric, character, and date data types to store comprehensive employee information.

Analogy: Grocery Store Inventory

Think of a grocery store inventory system where a "Products" table stores "ProductID" (INT), "ProductName" (VARCHAR(255)), and "ExpirationDate" (DATE). Each data type is chosen to accurately represent the nature of the data being stored.

Conclusion

Understanding SQL data types is crucial for designing efficient and accurate databases. By choosing the appropriate data types for numeric, character, and date/time data, you ensure that your database can handle and store information effectively, making it easier to manage and query the data.