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

STATEMENT_DIGEST_TEXT(statement) is a MySQL built-in function that normalizes a given MySQL statement into a statement digest. For example:

SELECT STATEMENT_DIGEST_TEXT('SELECT NOW()');
  -- +---------------------------------------+
  -- | STATEMENT_DIGEST_TEXT('SELECT NOW()') |
  -- +---------------------------------------+
  -- | SELECT NOW ( )                        |
  -- +---------------------------------------+

SELECT STATEMENT_DIGEST_TEXT('SELECT help_topic_id, name FROM mysql.help_topic');
  -- +---------------------------------------------------------------------------+
  -- | STATEMENT_DIGEST_TEXT('SELECT help_topic_id, name FROM mysql.help_topic') |
  -- +---------------------------------------------------------------------------+
  -- | SELECT `help_topic_id` , NAME FROM `mysql` . `help_topic`                 |
  -- +---------------------------------------------------------------------------+

Note that multiple MySQL statements may have the same statement digest. 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` = ? |
  -- +---------------------------------------------------------+

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` = ? |
  -- +---------------------------------------------------------+

Also note that STATEMENT_DIGEST_TEXT() 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_TEXT('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_TEXT() function:

STATEMENT_DIGEST_TEXT(statement): str
  Normalizes a given MySQL statement into a statement digest.

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

Related MySQL functions:

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

⇒ UNCOMPRESS() - Uncompressing Data

⇐ STATEMENT_DIGEST() - Statement Digest Hash

⇑ MySQL Functions for Encryption and Compression

⇑⇑ MySQL Function References