CRC32 Function

Overview

The CRC32 function computes the CRC-32 cyclic redundancy check value for a given string. CRC-32 is based on the IEEE 802.3 standard and can map arbitrary-length data to a 32-bit unsigned integer checksum value, commonly used for data integrity verification and error detection.

Syntax

crc32(expr)

Parameters

• expr: The input data for which to compute the CRC-32 checksum value. Supports STRING, VARCHAR, and CHAR types.

Return Result

Returns a BIGINT type value representing the computed CRC-32 checksum value (range: 0 to 4294967295).

Examples

1. Compute the CRC32 value of a simple string:

   SELECT crc32('hello') AS res; +-----------+ | res | +-----------+ | 907060870 | +-----------+

2. Compute the CRC32 value of a string containing special characters:

   SELECT crc32('Hello, World!') AS res; +------------+ | res | +------------+ | 3964322768 | +------------+

3. When the input is NULL:

   SELECT crc32(NULL) AS res; +------+ | res | +------+ | NULL | +------+

Notes

• CRC32 returns a BIGINT type integer value rather than a hexadecimal string, which differs from the SHA series hash functions.
• CRC-32 is a cyclic redundancy check algorithm, not a cryptographic hash function. It is not suitable for security-related scenarios (such as password storage or digital signatures).
• CRC-32 outputs a 32-bit unsigned integer, with a value range of 0 to 4294967295.
• When the input parameter is NULL, the result is NULL.
• CRC-32 is suitable for scenarios such as data transmission verification and file integrity checking.