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A MySQL adatbáziskezelő rendszernél a külső kulcsok használata csak InnoDB típusú táblaszerkezetnél lehetséges, a InnoDB szerkezetű táblák nem támogatják.

Monitorozás

http://alvinalexander.com/blog/post/mysql/how-show-open-database-connections-mysql^{Image Removed}

The MySQL show status command

You can show MySQL open database connections (and other MySQL database parameters) using the MySQL show status command, like this:mysql> show status like 'Conn%';
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1 row in set (0.00 sec)

mysql> show status like '%onn%';
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7 rows in set (0.00 sec)
All those rows and values that are printed out correspond to MySQL variables that you can look at. Notice that I use like 'Conn%'in the first example to show variables that look like "Connection", then got a little wiser in my second MySQL show status query.

MySQL show processlist

Here's what my MySQL processlist looks like when I had my Java application actively running under Tomcat:mysql> show processlist;
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4 rows in set (0.00 sec)
And here's what it looked like after I shut Tomcat down:mysql> show processlist;
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1 row in set (0.00 sec)