What is the difference between CHAR and VARCHAR in SQL?

The main difference between CHAR and VARCHAR in SQL lies in how they store data and handle storage space.

CHAR is a fixed-length data type, while VARCHAR is a variable-length data type.

For example, if I define a column as CHAR(10) and store the value 'CAT', SQL will still reserve 10 characters of space — it’ll store 'CAT ' (with trailing spaces). On the other hand, if I use VARCHAR(10), it’ll only use 3 characters of space for 'CAT', saving storage.

So, I usually choose:

• CHAR for columns where the data length is always consistent, like gender codes ('M', 'F'), country codes ('IND', 'USA'), or fixed-format identifiers.
• VARCHAR for columns where the data length varies, like names, addresses, or descriptions.

Here’s a small example:

CREATE TABLE Example (
    Code CHAR(5),
    Name VARCHAR(50)
);

In one of my projects, we had a table for storing product codes and descriptions. Product codes were always 8 characters, so I used CHAR(8). But for product descriptions, which varied in length, I used VARCHAR(200) to save space.

A challenge I’ve faced with CHAR is that when comparing or inserting values, trailing spaces can sometimes cause unexpected results, especially across different databases.

Performance-wise, CHAR can be slightly faster for fixed-length data because it’s predictable in size, but for large text or inconsistent-length data, VARCHAR is definitely more efficient.

So in short —

• CHAR = fixed length, uses more space but faster for uniform data.
• VARCHAR = variable length, space-efficient and flexible for varied data.