VARCHAR(n)

The variable-length character type (VARCHAR) stores strings of variable length. Unlike fixed-length types, VARCHAR only consumes storage space for the actual content, making it suitable for string data with highly variable lengths.

Syntax

VARCHAR(n)

Parameters

Value Range

• Minimum length: 1 character
• Maximum length: 1048576 characters (1 MB)
• Storage space is allocated based on actual content length; unused space is not padded with spaces

Examples

1. Create a table with VARCHAR columns:

   CREATE TABLE doc_test.varchar_demo (
       id INT,
       name VARCHAR(50),
       description VARCHAR(200)
   );
   

2. Cast an integer to VARCHAR:

   SELECT CAST(12345 AS VARCHAR(20));
   

   Result: 12345

3. Cast a string to VARCHAR of specified length:

   SELECT CAST('hello' AS VARCHAR(100));
   

   Result: hello

4. Use the maximum length VARCHAR(1048576):

   SELECT CAST('x' AS VARCHAR(1048576));
   

   Result: x

5. NULL value handling:

   SELECT CAST(NULL AS VARCHAR(50));
   

   Result: NULL

Notes

• The maximum length is 1048576 (approximately 1 MB), not 65535. The declared column type n must not exceed this value.
• When the inserted string length exceeds n, the behavior (error or truncation) depends on the specific operation.
• VARCHAR is case-sensitive; comparisons are performed character by character.
• When storing multi-byte characters (e.g., Chinese characters), n represents the number of characters, not bytes.
• If a CAST conversion fails (e.g., converting an incompatible type to VARCHAR), it returns NULL.