betweenGo

(Photo: Dolphin Crest by jurvetson)

I was wondering how to do this and thankfully someone wrote up a nice article on the SQL update statement.

Here is their example of how to do this.

UPDATE suppliers
SET name =
  ( SELECT customers.name
  FROM customers
  WHERE customers.id = suppliers.id)
WHERE EXISTS
  ( SELECT customers.name
  FROM customers
  WHERE customers.id = suppliers.id);

Thanks to this article, Oracle/PLSQL: Change a user’s password in Oracle, it was quite simple to change a user’s password.

SQL> alter user frank identified by password;

Whenever I tried to start my local TNS Listener service, OracleOraDb10g_home1TNSListener, I would get an error like this.

The OracleOraDb10g_home1TNSListener service on Local Computer started and then stopped. Some services stop automatically if they have no work to do, for example, the Performance Logs and Alerts service.

This forum thread, Can’t start Oracle service, suggested I do the following to diagnose the problem.

1. cmd
2. lsnrctl
3. start

This worked and I saw the following error which showed my Oracle install had not been properly done, the listener was pointing to the wrong server.

LSNRCTL> start
System parameter file is
  C:\oracle\product\10.2.0\db_1\network\admin\listener.ora
Error listening on:
  (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=bad.betweengo.com)(PORT=1521)))
TNS-12545: Connect failed because target host or object does not exist
 TNS-12560: TNS:protocol adapter error
  TNS-00515: Connect failed because target host or object does not exist
    32-bit Windows Error: 1004: Unknown error

In C:\oracle\product\10.2.0\db_1\network\admin\listener.ora the listener is improperly configured for bad.betweengo.com.

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = bad.betweengo.com)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )

I ran Oracle’s Net Configuration Assistant and updated the Listener configuration which fixed the above listener to point to my server. Now C:\oracle\product\10.2.0\db_1\network\admin\listener.ora points correctly to good.betweengo.com.

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = good.betweengo.com)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )

When I run rake db:migrate I get this error at the end.

Error in my_thread_global_end(): 1 threads didn't exit

I pinned it down to this code in one of my migration files.

# create admin user
user = User.new
user.login = 'admin'
user.password = 'password'
user.save(false)

If I don’t run user.save(false) I don’t get the error. I am not sure why, the user does get saved properly to the database.

I saw this post on the MySQL forums that seemed to indicate it was an issue with libmySQL.dll. So I upgraded my MySQL instance from 5.0.27 to 5.0.51a. Of course this did not go smoothly, I got this error when trying to reconfigure the MySQL server instance “MySQL service could not be started error 0″. Fortunately another post on the MySQL forums, Could not start service : Error 2003, solved this problem for me. I just had to remove the following files from the mysql/data directory.

• ib_logfile0
• ib_logfile1
• ibdata1

Unfortunately when I then did a rake db:migrate I saw this error.

Mysql::Error: Table 'prayer.schema_info' doesn't exist:
SELECT version FROM schema_info

After deleting and recreating the database I was finally able to run rake db:migrate. Unfortunately I still got the same error that inspired this post.

Googling some more I saw a MySQL bug report, MySQL Bugs: #25621: Error in my_thread_global_end(): 1 threads didn’t exit. Apparently this is a client side issue and I think I can safely ignore it though it is quite annoying.

Strictly speaking, this is not MySQL bug. This is a client bug – a client application (PHP, probably) linked with libmysqlclient calls my_thread_init() but does not call my_thread_end() as appropriate (doesn’t call at all or calls too late). MySQL client library detects this and issues a warning.

On the other hand, we can just remove the check and let buggy applications to fail some other way. Not calling my_thread_end() is a guaranteed memory leak. Calling it too late could easily crash the application.

With MySQL listing all the tables in a database is easy enough.

mysql> show tables;

With Oracle it’s a little less straight-forward.

> select table_name from user_tables;

OR

> select * from user_objects where object_type = 'TABLE'; 

OR

> select table_name from tabs;

OR

> select table_name from all_all_tables;

Today when I started up phpMyAdmin (version 2.10.0.2) by going to http://localhost/phpMyAdmin I saw this error screen.

I googled around but could not find any solutions.

So I went and tried to install the latest version of phpMyAdmin, 2.11.5. When I tried to run setup I saw this error screen.

Now that I had an error message to work with I googled around and found this post, Xampp phpMyAdmin Problem, which helped me diagnose the problem.

It turns out during one of my cleaning sessions I wiped out the session directory in, “C:\DOCUME~1\fkim\LOCALS~1\Temp\php\session.” After restoring it I ran into my next problem.

I upgraded to PHP 5.2.5 from 5.2.1 but that did not help. I installed the mbstring module but that did not help.

Finally I added the PHP extension directory to the path (I had already added the PHP directory to the path) and it finally worked! My path now includes the following two directories, E:\Program Files\PHP and E:\Program Files\PHP\ext.

I have a table of data that tracks the mileage of my beloved 2005 Toyota Prius.

+----+------------+---------+---------+-------+
| id | date       | mileage | gallons | cost  |
+----+------------+---------+---------+-------+
|  1 | 2005-02-14 |     280 |   8.615 | 16.03 |
|  2 | 2005-02-27 |     480 |   4.775 |  8.59 |
|  3 | 2005-03-19 |     713 |   7.213 | 14.27 |
|  4 | 2005-04-09 |     999 |    7.86 | 16.81 |
|  5 | 2005-04-11 |    1172 |   3.174 |  6.63 |
|  6 | 2005-05-05 |    1560 |   8.889 | 18.66 |
|  7 | 2005-06-07 |    1985 |   9.815 | 20.01 |
|  8 | 2005-07-03 |    2444 |   9.868 |  21.7 |
|  9 | 2005-08-13 |    2762 |   7.728 |    20 |
| 10 | 2005-09-11 |    3271 |  10.072 | 30.11 |
| 11 | 2005-10-24 |    3646 |   8.953 | 22.19 |
| 12 | 2005-10-30 |    3959 |   6.583 | 17.11 |
| 13 | 2005-11-04 |    4184 |   4.538 | 11.25 |
| 14 | 2005-11-21 |    4631 |   8.742 |    18 |
| 15 | 2005-12-31 |    4897 |   8.511 | 18.64 |
| 16 | 2006-02-02 |    5609 |    7.83 |    18 |
| 17 | 2006-03-01 |    6064 |    3.38 |  7.16 |
| 18 | 2006-03-13 |    6400 |   7.171 |  16.2 |
| 19 | 2006-03-22 |    6605 |   5.399 | 13.17 |
| 22 | 2006-02-16 |    5944 |   7.957 |  17.5 |
| 20 | 2006-04-06 |    6974 |   7.774 | 19.43 |
| 21 | 2006-04-23 |    7316 |   7.102 | 20.45 |
+----+------------+---------+---------+-------+

I wanted a way to calculate how many miles were driven for each trip, i.e. between consecutive dates, and what was the miles per gallon (MPG) for that trip.  To do this I modified what I learned in this post, unique ID field, getting next and previous existing ID from table to create a view that does all these calculations.  The advantage of this view is that it does not matter what order I enter the data, it will always calculate correctly.

CREATE VIEW v_prius_mpg AS
  SELECT id, date, mileage, gallons, cost, mileage as trip_mileage,
         mileage / gallons AS mpg, cost / gallons AS price_per_gallon
    FROM prius_mpg
    WHERE id = 1
  UNION
  SELECT New.id AS id, New.date, New.mileage, New.gallons, New.cost,
        (New.mileage - Old.mileage) AS trip_mileage,
        (New.mileage - Old.mileage)/ New.gallons AS mpg,
        (New.cost / New.gallons) AS price_per_gallon
    FROM prius_mpg New, prius_mpg Old
    WHERE New.id > 1
      AND Old.id =
        (SELECT id
           FROM prius_mpg
           WHERE date < New.date
           ORDER BY date DESC
           LIMIT 1);

And here are the results of the view.  Note how row 20 is out of order but it still calculates correctly the trip mileage and MPG.

+----+------------+---------+---------+--------------+------------------+
| id | date       | mileage | gallons | trip_mileage | mpg              |
+----+------------+---------+---------+--------------+------------------+
|  1 | 2005-02-14 |     280 |   8.615 |          280 |  32.501450957632 |
|  2 | 2005-02-27 |     480 |   4.775 |          200 | 41.8848167539267 |
|  3 | 2005-03-19 |     713 |   7.213 |          233 | 32.3027866352419 |
|  4 | 2005-04-09 |     999 |    7.86 |          286 | 36.3867684478371 |
|  5 | 2005-04-11 |    1172 |   3.174 |          173 | 54.5053560176434 |
|  6 | 2005-05-05 |    1560 |   8.889 |          388 | 43.6494543818202 |
|  7 | 2005-06-07 |    1985 |   9.815 |          425 |  43.301069791136 |
|  8 | 2005-07-03 |    2444 |   9.868 |          459 | 46.5139845966761 |
|  9 | 2005-08-13 |    2762 |   7.728 |          318 | 41.1490683229814 |
| 10 | 2005-09-11 |    3271 |  10.072 |          509 | 50.5361397934869 |
| 11 | 2005-10-24 |    3646 |   8.953 |          375 | 41.8854015413828 |
| 12 | 2005-10-30 |    3959 |   6.583 |          313 | 47.5467112258849 |
| 13 | 2005-11-04 |    4184 |   4.538 |          225 | 49.5813133539004 |
| 14 | 2005-11-21 |    4631 |   8.742 |          447 | 51.1324639670556 |
| 15 | 2005-12-31 |    4897 |   8.511 |          266 | 31.2536717189519 |
| 16 | 2006-02-02 |    5609 |    7.83 |          712 | 90.9323116219668 |
| 17 | 2006-03-01 |    6064 |    3.38 |          120 | 35.5029585798817 |
| 18 | 2006-03-13 |    6400 |   7.171 |          336 | 46.8553897643285 |
| 19 | 2006-03-22 |    6605 |   5.399 |          205 | 37.9699944434154 |
| 20 | 2006-02-16 |    5944 |   7.957 |          335 | 42.1012944577102 |
| 21 | 2006-04-06 |    6974 |   7.774 |          369 |  47.465912014407 |
| 22 | 2006-04-23 |    7316 |   7.102 |          342 | 48.1554491692481 |
+----+------------+---------+---------+--------------+------------------+

I always wanted to appear on every row how many gallons of gas had been consumed up to that day and how much had spent on gas up to date but I could not figure out how.  The only thing I could do was determine the sums up until now.

mysql> select sum(gallons) as gallons_to_date,
       sum(cost) as cost_to_date from prius_mpg where date <= current_date;
+-----------------+--------------+
| gallons_to_date | cost_to_date |
+-----------------+--------------+
|         161.949 |       371.91 |
+-----------------+--------------+
1 row in set (0.01 sec)

Today I was using the CategoryLookup droplet to find a category’s child products. However when I accessed the child products I would get this JDBC error.

java.lang.NullPointerException
at java.lang.String.(String.java:166)
at oracle.sql.CharacterSet.AL32UTF8ToString(CharacterSet.java:1517)

I realized my product data was corrupted. However this category had over 70 child products. The stack trace wasn’t telling me which one was corrupt and going through each child product to find out which one was corrupt was too painful.

I first queried the database to find all the child product ID’s.

SQL> select child_prd_id from dcs_cat_chldprd where category_id='cat101' order by sequence_num;

I then created a simple JHTML page which would query each child product and output which ones were corrupted.

<java>
final String [] product_ids = { "prod101", "prod102", "prod103" };

for (int ii = 0; ii < product_ids.length; ii++) {
out.print(ii + ". [" + product_ids[ii] + "] ");
try {
</java>
<droplet name="/atg/commerce/catalog/ProductLookup">
<param name="id" value="`product_ids[ii]`">
<oparam name="output">
<valueof param="element.displayName"/><br/>
</oparam>
</droplet>
<java>
} catch (RuntimeException exc) {
out.println(exc + "<br>");
}
}
</java>

Once I knew which child products were bad I removed their mappings to the category in dcs_cat_chldprd.

SQL> delete from dcs_cat_childprd where child_prd_id = 'prod102' and category_id='cat101';

Then I updated the sequence numbers so that they are all consecutive by moving the ones at the end to fill the holes created by the previous deletes.

SQL> update dcs_cat_childprd set sequence_num = 1 where child_prd_id = 'prod103' and category_id='cat101';

Sometimes I am faced with a situation where I need to know the source for a view or a procedure or a function. Fortunately Oracle stores the source in the database.

First I check to see what kind of object whose source I need is.

SQL> select object_name,object_type,status from user_objects where object_name = 'FOO';

If the object is a table I can simply recreate the table by doing a desc on that object.

SQL> desc FOO;

If the object is a function or stored procedure you can find its source in the user_source table.

SQL> select text from user_source where name = 'FOO' order by line;

If the object is a view you can find its source in the user_views table.

SQL> select text from user_views where view_name = 'FOO';

If the output seems to be truncated it is because text is of type LONG which is a big binary field. To allow more output do this.

SQL> set long 4000

Thanks to this article and this forum for helping me figure this out.

SQL> select privilege from user_tab_privs where lower(table_name)=’t_foo’ and lower(grantee)=’frank’;

PRIVILEGE
—————————————-
UPDATE
SELECT
INSERT
DELETE

SQL> select * from user_role_privs;

USERNAME GRANTED_ROLE ADM DEF OS_
—————————— —————————— — — —
FRANK AQ_ADMINISTRATOR_ROLE NO YES NO
PUBLIC SELECT_CATALOG_ROLE NO YES NO