PL-SQL engine In Oracle Tools:

When it holds the PL/SQL engine, an application development tool can procedure PL/SQL blocks. Tool passes the blocks to its local PL/SQL engine. An engine executes all procedural statements at the application site and sends only SQL statements to Oracle. Therefore, most of the work is done at the application site not at the server site.

In addition, if the block holds no SQL statements then the engine executes the whole block at the application site. This is useful if the application can advantage from iterative and conditional control.

Often, Oracle Forms applications use SQL statements merely to test the value of field entries or to do simple computations. Via using PL/SQL in other words, calls to the Oracle Server can be avoided. Furthermore, PL/SQL functions can be used to manipulate field entries.