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Displaying posts with tag: mariadb_errors (reset)
MariaDB/MySQL: Procedures to easily work with the Diagnostics Area

Versione italiana

UPDATE 2013-08-30: I fixed 2 bugs and create a GitHub repo called sql_diagnostix. Sorry for not doing this before. If I (or someone else) find new bugs, I’ll update the repo.

The problem

To quickly see information about the errors and warnings generated by the last executed statement, we can use SHOW WARNINGS. However this statement’s results cannot be accessed via SQL, so they cannot be used for error handling within a stored program.

For that purpose we can use GET DIAGNOSTICS, which has two problems:

  • It requires a lot of code
  • There is not a trivial way to quicly show all info from Diagnostics Area.
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MariaDB/MySQL Error HANDLERs: advanced uses

This article explains some advanced uses for MySQL and MariaDB’s error HANDLERs. Some information is in MySQL documentation, but it’s rather sparse. Also, while MySQL manual is probably the best manual ever, I’ve found a major bug in errors documentation. So, these use cases are not so obvious. At least they weren’t for me, so I had to test them.

Notes about the examples in this article

All the examples are tested on MariaDB 10.0.3, but I’m sure that there is not difference in MySQL 5.6, and there should be no difference in any 5.* version.

In these examples we need to produce an error to test the server’s behavior. We’ll always use the same method: we’ll declare a `cur` cursor and we’ll try to CLOSE it without OPENing it – this causes a 1326 …

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MariaDB/MySQL: “Commands out of sync” error (2014)

Versione italiana

If you execute mysqli_multi() and later you try to execute mysqli_query() or mysqli_result(), you may get the infamous error 2014: Commands out of sync; you can't run this command now (SQLSTATE: HY000). This happens because you didn’t free all resultsets before executing another query. But probably, you didn’t even know that any resultset exists, because you executed statements like INSERT, DELETE, or DDL.

Well, here is a function which frees all resultsets, and an usage example:

 *      Free all resultsets from $dbCon.
 *      @param          mysqli          $dbCon  mysqli object.
 *      @return         void
function free_all_results(mysqli $dbCon)
    do { …
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