Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-9337

ALTER from DECIMAL and INT to DATETIME returns a wrong result

Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Fixed
    • 5.5(EOL), 10.0(EOL), 10.1(EOL)
    • 10.2.0
    • Temporal Types
    • None

    Description

      These two scripts:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a DATETIME);
      		 
      INSERT INTO t1 VALUES (1000);
      		 
      SELECT * FROM t1;
      		 

      DROP TABLE IF EXISTS t1,t2;
      		 
      CREATE TABLE t1 (a DATETIME);
      		 
      CREATE TABLE t2 (a INT);
      		 
      INSERT INTO t2 VALUES (1000);
      		 
      INSERT INTO t1 SELECT * FROM t2;
      		 
      SELECT * FROM t1;

      return

      +---------------------+
      		 
      | a                   |
      		 
      +---------------------+
      		 
      | 2000-10-00 00:00:00 |
      		 
      +---------------------+

      This script:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a INT);
      		 
      INSERT INTO t1 VALUES (1000);
      		 
      ALTER TABLE t1 MODIFY a DATETIME;
      		 
      SELECT * FROM t1;

      returns a different result:

      +---------------------+
      		 
      | a                   |
      		 
      +---------------------+
      		 
      | 0000-00-00 00:00:00 |
      		 
      +---------------------+

      All three cases are expected to return the same result.

      Attachments

        Issue Links

          blocks

          Epic - Created by Jira Software - do not edit or delete. Issue type for a big user story that needs to be broken down. MDEV-4912 Data type plugin API version 1

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Closed

          Activity

            bar Alexander Barkov added a comment -

            The same problem is repeatable with the DECIMAL data type:

            DROP TABLE IF EXISTS t1;
            		 
            CREATE TABLE t1 (a DATETIME);
            		 
            INSERT INTO t1 VALUES (1000.0);
            		 
            SELECT * FROM t1;

            and

            DROP TABLE IF EXISTS t1,t2;
            		 
            CREATE TABLE t1 (a DATETIME);
            		 
            CREATE TABLE t2 (a DECIMAL(4,0));
            		 
            INSERT INTO t2 VALUES (1000);
            		 
            INSERT INTO t1 SELECT * FROM t2;
            		 
            SELECT * FROM t1;

            return

            +---------------------+
            		 
            | a                   |
            		 
            +---------------------+
            		 
            | 2000-10-00 00:00:00 |
            		 
            +---------------------+

            While this script:

            DROP TABLE IF EXISTS t1;
            		 
            CREATE TABLE t1 (a DECIMAL(4,0));
            		 
            INSERT INTO t1 VALUES (1000);
            		 
            ALTER TABLE t1 MODIFY a DATETIME;
            		 
            SELECT * FROM t1;

            returns

            +---------------------+
            		 
            | a                   |
            		 
            +---------------------+
            		 
            | 0000-00-00 00:00:00 |
            		 
            +---------------------+

            bar Alexander Barkov added a comment - The same problem is repeatable with the DECIMAL data type: DROP TABLE IF EXISTS t1; CREATE TABLE t1 (a DATETIME); INSERT INTO t1 VALUES (1000.0); SELECT * FROM t1; and DROP TABLE IF EXISTS t1,t2; CREATE TABLE t1 (a DATETIME); CREATE TABLE t2 (a DECIMAL(4,0)); INSERT INTO t2 VALUES (1000); INSERT INTO t1 SELECT * FROM t2; SELECT * FROM t1; return +---------------------+ | a | +---------------------+ | 2000-10-00 00:00:00 | +---------------------+ While this script: DROP TABLE IF EXISTS t1; CREATE TABLE t1 (a DECIMAL(4,0)); INSERT INTO t1 VALUES (1000); ALTER TABLE t1 MODIFY a DATETIME; SELECT * FROM t1; returns +---------------------+ | a | +---------------------+ | 0000-00-00 00:00:00 | +---------------------+

            People

              bar Alexander Barkov
              bar Alexander Barkov
              Votes:
              0 Vote for this issue
              Watchers:
              1 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

                Git Integration

                  Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.