Choosing Correct Data Types in SQL

Factors to Consider When Choosing Data Types

Several factors influence the choice of data types, including storage size, precision, and query performance.

• Storage requirements: Smaller data types save disk space and memory.
• Data precision: Numeric types must accommodate the range and decimal precision needed.
• Performance: Smaller and simpler data types generally improve query speed.
• Data integrity: Correct types enforce valid data and prevent errors.

Common Data Type Choices and Best Practices

Here are practical recommendations for common data types to use in SQL.

• Use INT or BIGINT for whole numbers depending on the expected range.
• Use DECIMAL or NUMERIC for exact decimal values, such as currency.
• Use VARCHAR for variable-length strings and CHAR for fixed-length strings.
• Use DATE or DATETIME for storing dates and times instead of strings.
• Avoid using TEXT or BLOB unless necessary, as they can impact performance.

Examples of Choosing Correct Data Types

Let's look at some examples demonstrating appropriate data type choices.