Blocks:

A form holds one or more blocks. The Blocks are logical containers and have no physical representation. Simply the items contained in a block are visible in the form interface.

A block can be conceptualized as a parent container object which holds an associated group of child objects like as text lists, items, and push buttons, etc for displaying, storing, and manipulating table data. Every block has a group of properties which determine the behavior of the block.

A block connected to a database object is known as a ‘Data Aware’ block. The block not connected to any database object is known as ‘Control Block’. A block can be linked   to a database object like a table, view or synonym. The block can also be linked to ‘Stored Procedures’

Every Data Block can be straightly related to a (single) database table, view or synonym. A table synonym or view connected to a block is known as the ‘Base Table’. Every column of the base table might have a related block item bound to it. The binding of block or association items with table columns is done through giving the item on the block the similar name as the table column. This direct relationship permits the data in a base table to be manipulated at will.

Blocks have various characteristics which can be defined. Some of these are the attributes which determine how to sort information retrieved into a block from the base table and the number of records which can be displayed din the block and many more.

Blocks could be associated to each other through specifying a master-detail relationship. The master-detail relationship corresponds to a primary-foreign key relationship among the base tables of the blocks. When a row is retrieved in the master block from the master table and the master detail relationship automatically displays the corresponding set of rows from the detail table in the detail block with no special processing code being needed.