Tag: 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.

Oracle stored procedures and ColdFusion

I’ve heard for years that using Oracle’s stored procedures is both more efficient and more secure than writing queries against the database. It turns out, not everyone agrees with that and there is quite a bit of room for debate (most of the articles focus on MS-SQL Server and T-SQL, not Oracle and PL/SQL, although some general principles still apply):

I was still interested in how to use Oracle stored procedures with ColdFusion, though.
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