Category: Oracle

UPDATE rows with values from a table JOIN in Oracle

Example use case: I have a database that contains a table of contacts (contact) and table of e-mail addresses (email), joined on contact.id = email.contact_id. I just found out that Example Conglomerate acquired Osric Publishing’s Oracle consulting business, and so I need to update my contacts database so that all of the Oracle consultants who had @osric.com e-mail addresses now have @example.com e-mail addresses.

How can I change just the affected addresses in the contact database, assuming the username portion of their e-mail addresses remains the same?
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Querying an Oracle database from Powershell

I needed to query Oracle for information to use in a Powershell script. I found the following comprehensive blog post with details on how to do so using ODP.NET: Use Oracle ODP.NET and PowerShell to Simplify Data Access

The article is extremely long and goes into a lot of depth. The following is a short summary of the first steps, with just enough to get started:

  1. Download Oracle Data Provider for .NET (ODP.NET). (If that link doesn’t work just search for “Oracle ODP.NET”.)
    • Select “Download the latest ODP.NET production release.”
    • Select “64-bit ODAC Downloads”
    • Select “ODP.NET_Managed_ODAC12cR4.zip”
  2. Extract the ZIP file to C:\, which creates C:\ODP.NET_Managed_ODAC12cR4.
  3. Run cmd as administrator, navigate to C:\ODP.NET_Managed_ODAC12cR4, and run:
    install_odpm.bat C:\oracle\instantclient_10_2 both

In Powershell, add the DLL and set up a database connection and a query:

Add-Type -Path "C:\Users\chris\ODP.NET_Managed_ODAC12cR4\odp.net\managed\common\Oracle.ManagedDataAccess.dll"
$username = Read-Host -Prompt "Enter database username"
$password = Read-Host -Prompt "Enter database password"
$datasource = Read-Host -Prompt "Enter database TNS name"
$query = "SELECT first_name, last_name FROM users.user WHERE first_name = 'Chris' ORDER BY last_name"
$connectionString = 'User Id=' + $username + ';Password=' + $password + ';Data Source=' + $datasource
$connection = New-Object Oracle.ManagedDataAccess.Client.OracleConnection($connectionString)
$connection.open()
$command=$connection.CreateCommand()
$command.CommandText=$query
$reader=$command.ExecuteReader()
while ($reader.Read()) {
$reader.GetString(1) + ', ' + $reader.GetString(0)
}
$connection.Close()

Output of the above:

Brown, Chris
Carter, Chris
Jones, Chris
Smith, Chris

ORA-00904: “WM_CONCAT”: invalid identifier

I’ve never run into wm_concat before when using Oracle, but I saw it in a statement similar to this earlier today:

SELECT WM_CONCAT(id)
FROM chris.item
WHERE item_type LIKE '%floppy%';

Of course, it didn’t work:

ORA-00904: "WM_CONCAT": invalid identifier

It looks like WM_CONCAT isn’t a supported command (Error when using wm_concat function), and possibly the code I was debugging stopped working when the database was upgraded to 12c.

WM_CONCAT is intended to return the results as a comma-separated list. A strange idea, but it this particular case it almost made sense. A supported replacement that aggregates results into a single string is LISTAGG.

SELECT LISTAGG(id, ',')
WITHIN GROUP (ORDER BY id)
FROM chris.item
WHERE item_type LIKE '%floppy%'
GROUP BY 1;

In this case, I did not want the results separated into groups, so I used GROUP BY 1 to put all results in the same group.

There are a number of other string aggregation techniques for Oracle, if you ever find yourself with such a need.

Connecting to Oracle instance in AWS RDS

I inherited a development Oracle instance in Amazon Web Services’s Relational Database Service (AWS RDS) from a former colleague. I wanted to know what was in the database, and for that, I had to connect to it. I decided the most straightforward way would be with the simplest tool: SQL*Plus.
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Toad and Oracle Home

I recently upgraded work PC. One of the bigger hassles was setting up Toad and my Oracle connections again.

Steps (and mis-steps) I took:

  • I downloaded an Instant Client from the Oracle Instant Client Downloads
  • I selected a 32-bit client because I recall that Toad is picky about that, and a 10.2 client. I picked 10.2 primarily because I think that is what I had before, but also because I had downloaded a 64-bit 12.1 client that definitely did not work.
  • I copied it to my computer: C:\oracle\instantclient_10_2. That location is arbitrary–you should be able to save it anywhere.
  • I added an ORACLE_HOME environment variable (although this appears to have been unnecessary):
    C:\> SET ORACLE_HOME=C:\oracle\instantclient_10_2
  • I copied my old tnsnames.ora file to the same folder.
  • Start Toad

Error!
“No valid Oracle Client found. Please note that Toad only supports 32 bit Oracle Client installations. Please view the release notes for additional system requirements.”

When I try to select a client from the installed clients menu, another error:
“You do not have any Oracle homes installed!”

I had to add the client to the PATH environment variable. There are a couple ways you can do this:

  • C:\> PATH=%PATH%;C:\oracle\instantclient_10_2
  • Go to Control Panel — System — Advanced System Settings — Environment Variables — System Variables — Edit

Toad then started without the error, but also did not recognize my tnsnames.ora file.

First I tried adding the TNS_ADMIN environment variable via the command-line:
C:\> SET TNS_ADMIN=C:\oracle\instantclient_10_2

For whatever reason, that did not solve the problem. I could echo the value back with echo %TNS_ADMIN%, but it did not appear under Environment Variables in the Control Panel.

I added TNS_ADMIN as a user environment variable in the Control Panel, restarted Toad, and then it recognized my tnsnames.ora file.