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I used Mathematica to access the data of a MariaDB MySQL database. Within the version 12.0 it worked well on linux using the following code:

Needs["DatabaseLink`"]
conn = OpenSQLConnection["OpenHAB"];

I defined the connection properties successfully like this:

  • User Lever
  • MySQL(Connector/J)
  • com.mysql.jdbc.Driver
  • jdbc:mysql://
  • IP, port, username, password

After switching to Mathematica 12.2 everything works fine just after fresh installation.

After the second start of Mathematica the connection gets the following error:

KeyExistsQ::invrl: The argument Association[Flatten[JDBCDrivers[]/. JDBCDriver[Name->DatabaseLink`SQL`Private`name_,Driver->DatabaseLink`SQL`Private`driver_,Protocol->DatabaseLink`SQL`Private`protocol_,_,_,_]:>{DatabaseLink`SQL`Private`name->Association[Rule[<<2>>],Rule[<<2>>]]}]] is not a valid Association or a list of rules.

From the second start on I can not bring the connection back on line. If I use the assistant under

OpenSQLConnection[]

to delete the connection and to set it up again it will fail also. If I use the Test button within the assistant I get

Error:KeyExistQ::invrl

The only way to bring the connection back at least once is to uninstall Mathematica completely and do a fresh install. As this works until the next start of Mathematica it is not a very suitable for working.

Thanks

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2 Answers 2

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The KeyExistQ error is caused by a malformed JDBC configuration file. Unluckily the documentation on how to set up JDBC configuration files is no longer correct for 12.2.

A JDBC driver configuration is expected to have the five keys "Name", "Driver", "Protocol", "Version" and "Description" in the correct order, e.g.:

JDBCDriver[
    "Name" -> "Oracle(thin)",
    "Driver" -> "oracle.jdbc.driver.OracleDriver",
    "Protocol" -> "jdbc:oracle:thin:@",
    "Version" -> DatabaseLink`Information`$VersionNumber, 
    "Description" -> "Oracle Thin Driver"
]

In 12.3 (which ships with DatabaseLink 3.0.1) the issue has been partially fixed. Changing the order of the named keys in JDBCDriver however still triggers the KeyExistQ error.

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Thanks for reporting this. Unfortunately, Mathematica 12.2 has this bug but this should be fixed by the newer paclet release.

For now, a workaround could be by using JDBC driver connection as below:

conn = Quiet[
  OpenSQLConnection[
   JDBC["com.mysql.jdbc.Driver", "jdbc:mysql://" <> "hostname"], 
   "Username" -> "user", "Password" -> "Password"]]
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  • $\begingroup$ Thank you for your answer. I tested the workaround and it fixed the problem. Wolfram support suggested to do the same. $\endgroup$
    – Tschibi
    Mar 3, 2021 at 19:39

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