Technology Questions

Classes that contain at least one pure virtual function are called as abstract base classes.

we can always fetch from one database and rewrite to another. Here is a nice solution of it.$db1 = mysql_connect("host","user","pwd")
mysql_select_db("db1", $db1);
$res1 = mysql_query("query",$db1);$db2 = mysql_connect("host","user","pwd")
mysql_select_db("db2", $db2);
$res2 = mysql_query("query",$db2);At this point you can only fetch records from you previous ResultSet, i.e $res1 – But you cannot execute new query in $db1, even if you supply the link as because the link was overwritten by the new db.so at this point the following script will fail
$res3 = mysql_query("query",$db1); //this will failSo how to solve that?

take a look below.
$db1 = mysql_connect("host","user","pwd")
mysql_select_db("db1", $db1);
$res1 = mysql_query("query",$db1);

$db2 = mysql_connect("host","user","pwd", true)
mysql_select_db("db2", $db2);
$res2 = mysql_query("query",$db2);

So mysql_connect has another optional boolean parameter which indicates whether a link will be created or not, as we connect to the
$db2 with this optional parameter set to 'true', so both link will remain live.

Now the following query will execute successfully.
$res3 = mysql_query("query",$db1);

SELECT  * from Employees  WHERE  upper(EmpName) like upper('joe%');

There are two kinds of classes in c++. They are absolute class and concrete class.

DAO (Data access object ) is used for accessing data before ado it was used for database installed on same sys where the application resides.

RDO (Remote data object ) is used for accessing remote data

ADO (Active data object ) most powerful till date it is nothing but combination of both DAO and RDO 

There are two types of modular programming.They are interface and implementation.

The mail() function allows you to send emails directly from a script.