What is the difference between char and varchar in mysql

CHAR and VARCHAR are two data types for storing strings in MySQL. CHAR is fixed length, VARCHAR is variable length, and only the minimum storage space required is allocated. CHAR strings are padded to the specified length, while VARCHAR are not padded. CHAR is based on fixed length comparison, VARCHAR is based on actual length comparison. Choose CHAR or VARCHAR based on string length and comparison needs.

The difference between CHAR and VARCHAR in MySQL

In MySQL, CHAR and VARCHAR are two different types of data Type used to store strings. The main differences between them are storage space allocation and string length handling.

Storage space allocation

• CHAR: Fixed length data type. Allocates space of the specified size for each CHAR field, even if it contains no data. For example, a field defined as CHAR(10) is always allocated 10 bytes, regardless of the actual data length.
• VARCHAR: Variable length data type. Allocate only the minimum space required to store the actual string data. For example, a field defined as VARCHAR(10) allocates 1 byte when storing an empty string and 9 bytes when storing a 9-character string.

String length handling

• CHAR:Always pad strings to the specified length, with Space padding.
• VARCHAR: Only the actual length of the string is stored, without padding. If the specified length is longer than the actual string, the excess space is stored.

Other differences

• Comparison operations: The comparison of CHAR fields is based on fixed length, while the comparison of VARCHAR fields is based on actual length.
• Indexing: VARCHAR fields are often indexed without retaining a specified length to improve performance.
• Sort: CHAR fields are usually sorted alphabetically, while VARCHAR fields are sorted by actual length.

Choose CHAR or VARCHAR

Choose CHAR or VARCHAR depends on the following factors:

• Storage space: If the string length is usually short and fixed, CHAR is more efficient. If the string length is variable and long, VARCHAR is more efficient.
• Comparison operation: If you need to compare strings by fixed length, use CHAR. Otherwise, use VARCHAR.
• Index: Use VARCHAR if you do not need the fixed length of the index.

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