Concept of a two-dimensional table:
Concept of a two-dimensional table can be easily extended to tables having three or more dimensions. The Handling of tables up to three dimensions is permitted by most compilers; some even allow more than three. The rules below may be noted in connection with multi-dimensional tables.
(i) The Multi-dimensional tables are to be defined as records with OCCURS clauses at different levels. As we go down the hierarchy, each lower level item with an OCCURS clause identifies an additional dimension. For illustration, consider the table shown below:
(ii)
A & C are one-dimensional, F is a two-dimensional table and E is a three dimensional table. B & D are group items that can be referred to as one-dimensional and two dimensional tables correspondingly.
(ii) A table is stored in such a way that a subscript on the right of the other subscript changes more rapidly than the later.
The organization of the SALES-TABLE shown above describes this. The elements MONTHLY-SALES (1, 12) are stored first. The elements MONTHLY-SALES (2, 1) to
MONTHLY-SALES (2, 12) are stored next, and so on. Keep in mind that the second subscript is changed more regularly than the first subscript. This fact must be taken into consideration while redefining a multi-dimensional table.
(iii) The Multiple subscripts must be separated from one another either by a space or comma.