MySQL interface of Perl DBI: An Example

Source code:#! /Usr/bin/perl-w
# Test. pl-Perl DBI test

Use strict;
Use DBI;

My $ dsn = "DBI: mysql: db1: 10.1.9.110"; # data source name
My $ user_name = "user1"; # user name
My $ password = "passwd1"; # password

# Connect to database
My $ dbh = DBI-> connect ($ dsn, $ user_name, $ password, {RaiseError => 1, PrintError => 0 });

# Issue query
My $ something = $ dbh-> prepare ("select * from month. temp order by id asc ");
My $ sth_bal;
My $ update_bal;
My $ delete_subtasks;

$ Something-> execute ();

$ Dbh-> do ("set foreign_key_checks = 0 ");

# Read resules of query, then clean up
While (my ($ id, $ SubscriptionID, $ UserID, $ ServiceID, $ Price) = $ something-> fetchrow_array ())
{
$ Sth_bal = $ dbh-> prepare ("select c1 from db1.t1 where UserID = $ UserID ");
$ Sth_bal-> execute ();
My ($ balance) = $ sth_bal-> fetchrow_array ();

If ($ Price> $ balance)
{
$ Delete_subparts = $ dbh-> do ("delete from db1.t2 where c1 = $ SubscriptionID ");
If (! $ Delete_subtasks)
{
Print "an error occurredn ";
}
Else
{
# Print "subscriptionid: $ subscriptionid ";
# Print "N ";
}
$ DBH-> do ("insert into db2.log (optdate, opt, tablename, subscriptionid, userid, oldbal, newbal)
Values (curdate (), 'delete', 'servicesubregion', $ SubscriptionID, $ UserID, null, null )");
}
Else
{
$ Update_bal = $ dbh-> do ("update db1.t1 set UserBal = UserBal-$ Price where UserID = $ UserID ");
If (! $ Update_bal)
{
Print "An error occurredn ";
}
Else
{
# Print "userid: $ userid ";
# Print "N ";
}
$ DBH-> do ("insert into db2.log (optdate, opt, tablename, subscriptionid, userid, oldbal, newbal)
Values (curdate (), 'update', 'webuser', $ subscriptionid, $ userid, $ balance, $ balance-$ price )");
}
$ Sth_bal-> finish ();
}

$ Something-> finish ();

$ DBH-> do ("set foreign_key_checks = 1 ");

$ DBH-> disconnect ();
Exit (0 );