MySQL’s default configuration sets the maximum simultaneous connections to 100. If you need to increase it, you can do it fairly easily:
For MySQL 3.x:
# vi /etc/my.cnf set-variable = max_connections = 250
For MySQL 4.x and 5.x:
# vi /etc/my.cnf max_connections = 250
Restart MySQL once you’ve made the changes and verify with:
echo "show variables like 'max_connections';" | mysql
WHOA THERE: Before increasing MySQL’s connection limit, you really owe it to yourself (and your server), to find out why you’re reaching the maximum number of connections. Over 90% of the MySQL servers that are hitting the maximum connection limit have a performance limiting issue that needs to be corrected instead.