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  1. MariaDB Server
  2. MDEV-13793

Wrong result with combination of CONCAT,SUBSTR,SHA

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Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Duplicate
    • 10.0(EOL), 10.1(EOL), 10.2(EOL), 10.3(EOL)
    • N/A
    • OTHER
    • None

    Description

      This query erroneously returns NULL:

      SELECT UNHEX(CONCAT('414c2', HEX(8+ROUND(RAND()*7)),SUBSTR(SHA(''),6,7),HEX(2+ROUND(RAND())*8)));

      If I remove HEX, it correctly returns a string in hexadecimal format:

      SELECT CONCAT('414c2', HEX(8+ROUND(RAND()*7)),SUBSTR(SHA(''),6,7),HEX(2+ROUND(RAND())*8));


      +------------------------------------------------------------------------------------+
      		 
      | CONCAT('414c2', HEX(8+ROUND(RAND()*7)),SUBSTR(SHA(''),6,7),HEX(2+ROUND(RAND())*8)) |
      		 
      +------------------------------------------------------------------------------------+
      		 
      | 414c2B3ee5e6bA                                                                     |
      		 
      +------------------------------------------------------------------------------------+

      If I now add a user variable assignment, it erroneously returns a broken hexadecimal string:

      SELECT @a:=CONCAT('414c2', HEX(8+ROUND(RAND()*7)),SUBSTR(SHA(''),6,7),HEX(2+ROUND(RAND())*8));


      +----------------------------------------------------------------------------------------+
      		 
      | @a:=CONCAT('414c2', HEX(8+ROUND(RAND()*7)),SUBSTR(SHA(''),6,7),HEX(2+ROUND(RAND())*8)) |
      		 
      +----------------------------------------------------------------------------------------+
      		 
      | 414c299 ee56b2                                                                         |
      		 
      +----------------------------------------------------------------------------------------+

      The same problem is reproducible in a simplified query:

      SELECT @a:=CONCAT('2', '2', SUBSTR(SHA(''),6,7));


      +-------------------------------------------+
      		 
      | @a:=CONCAT('2', '2', SUBSTR(SHA(''),6,7)) |
      		 
      +-------------------------------------------+
      		 
      | 223ee5 6b                                 |
      		 
      +-------------------------------------------+

      Attachments

        Issue Links

          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-13790 UNHEX() of a somewhat complicated CONCAT() returns NULL

          • Major - Major loss of function.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-10306 Wrong results with combination of CONCAT, SUBSTR and CONVERT in subquery

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

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              bar Alexander Barkov
              bar Alexander Barkov
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              Dates

                Created:
                Updated:
                Resolved:

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