VARCHAR

Varchar is a variable-length character string data type used in many relational database management systems to store text data. The key feature is that the stored value uses only as many bytes as needed for the actual text, plus a small amount of overhead to record the length, unlike fixed-length types such as char.

Syntax and limits: A column defined as VARCHAR(n) specifies a maximum length, typically measured in characters. The exact maximum and whether length is in characters or bytes depends on the DBMS and the encoding in use. Some systems also allow variants such as VARCHAR without a limit or VARCHAR with a special maximum size, but others enforce an explicit bound. The practical maximum length is influenced by the database engine, character set, and row size constraints.

Storage and behavior: Because it is variable-length, VARCHAR generally uses less space for short strings, but longer strings can grow the storage proportionally. Comparisons and indexing are generally efficient, but very long entries can affect performance and row size. VARCHAR is usually preferred for fields where input length varies, while CHAR is used for fixed-length fields.

Usage considerations: Choose an appropriate maximum length to balance data integrity and storage. Be mindful of multibyte character encodings; the stated length may refer to characters or bytes depending on the system. Some DBMS provide large-object or text-like types for very long content, such as TEXT or CLOB, which should be chosen when lengths exceed practical VARCHAR limits. Examples: CREATE TABLE users (name VARCHAR(50), email VARCHAR(100)).