CHAR vs VARCHAR in Relational Databases

This page outlines the key differences between CHAR and VARCHAR data types used in relational databases like MySQL. These types are commonly used for storing string data but behave differently in terms of storage, performance, and usage.

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Overview

CHAR and VARCHAR are both used to store character strings, but they differ in how the data is stored and handled. Choosing the correct type is important for performance and storage efficiency.

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Key Differences

Feature	CHAR	VARCHAR
Storage Type	Fixed-length	Variable-length
Length Padding	Pads with spaces to full length	No padding
Performance	Slightly faster for fixed-size fields	More efficient for variable-length text
Storage Efficiency	Wastes space for short values	More compact for short/variable data
Max Length (MySQL)	Up to 255 characters (before MySQL 5.0.3) / 255 bytes	Up to 65,535 bytes (row size limit applies)
Trailing Spaces	Trailing spaces are removed during comparison	Trailing spaces are preserved

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Use Cases

• Use CHAR when:

  • All values have the same length (e.g., fixed-length codes like country codes, gender).
  • You prioritise slightly better performance over storage.

• Use VARCHAR when:

  • Data length varies significantly (e.g., names, addresses, descriptions).
  • You want to minimise storage space.

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Example

Creating a table with both types:

CREATE TABLE employees (
  emp_code CHAR(5),
  emp_name VARCHAR(100)
);