How to calculate MySQL statement digest hash using the STATEMENT_DIGEST() function?

STATEMENT_DIGEST(statement) is a MySQL built-in function that normalizes a given MySQL statement into a statement digest and returns the SHA-256 hash as a 64 hexadecimal digits string. For example:

SELECT STATEMENT_DIGEST('SELECT NOW()');
  -- +------------------------------------------------------------------+
  -- | STATEMENT_DIGEST('SELECT NOW()')                                 |
  -- +------------------------------------------------------------------+
  -- | 2fad55a506c3342fe82629447a3412f5dfb1aaaa20b13be45f1b9c42175da923 |
  -- +------------------------------------------------------------------+

SELECT STATEMENT_DIGEST('SELECT help_topic_id, name FROM mysql.help_topic');
  -- +----------------------------------------------------------------------+
  -- | STATEMENT_DIGEST('SELECT help_topic_id, name FROM mysql.help_topic') |
  -- +----------------------------------------------------------------------+
  -- | 7a0ad58a8e461ec08bbc4740055be7c272bf0bb684968e1bf39eafa49fd3c54c     |
  -- +----------------------------------------------------------------------+

Note that multiple MySQL statements may have the same statement digest. In that case, they will have the same statement digest hash. For example:

SET @stmt = 'SELECT * FROM mytable WHERE cola = 10 AND colb = 20';

SELECT STATEMENT_DIGEST_TEXT(@stmt);
  -- +---------------------------------------------------------+
  -- | STATEMENT_DIGEST_TEXT(@stmt)                            |
  -- +---------------------------------------------------------+
  -- | SELECT * FROM `mytable` WHERE `cola` = ? AND `colb` = ? |
  -- +---------------------------------------------------------+

SELECT STATEMENT_DIGEST(@stmt);
  -- +------------------------------------------------------------------+
  -- | STATEMENT_DIGEST(@stmt)                                          |
  -- +------------------------------------------------------------------+
  -- | 3bb95eeade896657c4526e74ff2a2862039d0a0fe8a9e7155b5fe492cbd78387 |
  -- +------------------------------------------------------------------+

SET @stmt = 'SELECT * FROM mytable WHERE cola = 1 AND colb = 2';

SELECT STATEMENT_DIGEST_TEXT(@stmt);
  -- +---------------------------------------------------------+
  -- | STATEMENT_DIGEST_TEXT(@stmt)                            |
  -- +---------------------------------------------------------+
  -- | SELECT * FROM `mytable` WHERE `cola` = ? AND `colb` = ? |
  -- +---------------------------------------------------------+

SELECT STATEMENT_DIGEST(@stmt);
  -- +------------------------------------------------------------------+
  -- | STATEMENT_DIGEST(@stmt)                                          |
  -- +------------------------------------------------------------------+
  -- | 3bb95eeade896657c4526e74ff2a2862039d0a0fe8a9e7155b5fe492cbd78387 |
  -- +------------------------------------------------------------------+

Also note that STATEMENT_DIGEST() validates the given MySQL statement before calculating the hash value. If an invalid statement is provided, you will get an error. For example:

SELECT STATEMENT_DIGEST('I AM NOT A STATEMENT');
ERROR 3676 (HY000): Could not parse argument to digest function: 
"You have an error in your SQL syntax; check the manual that corresponds 
to your MySQL server version for the right syntax to use near 
'I AM NOT A STATEMENT' at line 1".

Reference information of the STATEMENT_DIGEST() function:

STATEMENT_DIGEST(statement): hash
  Normalizes a given MySQL statement into a statement digest
  and returns the SHA-256 hash as a 64 hexadecimal digits string.

Arguments, return value and availability:
  statement: Required. The MySQL statement string to be processed.
  hash: Return value. The hash value of the statement digest.
  Available since MySQL 4.1.

Related MySQL functions:

• STATEMENT_DIGEST() - Statement Digest Hash
• STATEMENT_DIGEST_TEXT() - Calculating Statement Digest

⇒ STATEMENT_DIGEST_TEXT() - Calculating Statement Digest

⇐ SHA2() - Calculating SHA-2 Hash

⇑ MySQL Functions for Encryption and Compression

⇑⇑ MySQL Function References