Question

Why when I’m using jdbc to do inserts into my data base my table auto_increments gets jacked-up.

Example Of totally empty tables being populated:

Dog table

DogId DogName
3     Woofer
4     Kujo
5     Spike

Owner Table

OwnerId DogID OwnerName
6       3     George
7       4     John
8       5     Sam

Desired Results

Dog table

DogId DogName
1     Woofer
2     Kujo
3     Spike

Owner Table

OwnerId DogID OwnerName
1       1     George
2       2     John
3       3     Sam

Actual code:

 public void insertStuff(Something d)
  {
    Connection con = null;

    try
    {
      Class.forName("com.mysql.jdbc.Driver");
      con = (Connection) DriverManager.getConnection(
          "jdbc:mysql://" + this.getServer() + "/" + this.getDatabase(), user,
          password);
      con.setAutoCommit(false);

      Statement s1 = (Statement) con.createStatement();
      s1.executeUpdate("INSERT IGNORE INTO DOG (DOG_NAME) VALUES(\""
          + d.getDogName() + "\")");

      Statement s2 = (Statement) con.createStatement();
      s2.executeUpdate("INSERT IGNORE INTO OWNER (DOG_ID,OWNER_TITLE) VALUES ("
          + "(SELECT DOG_ID FROM DEVICE WHERE DOG_NAME =\""
          + d.getDogName()
          + "\"),\"" + d.getOWNER() + "\")");

      Statement s3 = (Statement) con.createStatement();
      s3.executeUpdate("INSERT IGNORE INTO KENNEL " + "("
          + "KENNEL_NAME,+ "OWNER_ID) " + "VALUES " + "( \""
          + d.getKennelName()
          + "\","
          + "\""
          + ","
          + "(SELECT OWNER_ID FROM OWNER WHERE OWNER_TITLE=\""
          + d.getOWNER() + "\")" + ")");

      }

      con.commit();

    }
    catch (Exception e)
    {
      if (con != null)
        try
        {
          con.rollback();
        }
        catch (SQLException e1)
        {
          // TODO Auto-generated catch block
          e1.printStackTrace();
        }

      e.printStackTrace();
    }
    finally
    {
      if (con != null)
        try
        {
          con.close();
        }
        catch (SQLException e)
        {
          // TODO Auto-generated catch block
          e.printStackTrace();
        }
    }
  }

Answer 1

Only two scenarios I know about are:

(1) some records have been deleted

(2) there is some trigger on table that modify such id

Please note that even you made fresh inserts to empty table, if there were previously some rows, emptying table don’t reset auto-increment ID counter and it continues on order from last issued number, not from the number of actual records in table…