Use of tables

Tables are one of the most important parts of a GIS. In tables (database or text tables) are stored a lot of information of spatial data. A grid can contain reference numbers for a table, for example the 31 states of Nigeria. For all of them are specific economic and ecologic information stored in text based tables. A simple query can join this information to the spatial data. The user must provide in P1 the table name, in P2 the name of the key and in P3 the name of the column to join. Using ASCII_Get (Mysql_Get) produces a new map named after the column to join. A fictive example may explain that:

This can be used in the following way:
P1: Nigeria.txt
P2: id
P3: Income

This will produce a map "Income" with the income of all states of Nigeria.

In the opposite way the Tabulate_Area operation can be used. After some calculation, for example the mean erosion of a state, it is useful to store this information in a table. For this reason was developed the Tabulate_area function. This function uses four inputs:

P1: name of the file
P2: name of the key code
P3: index map
highlighted: map with the results

This function creates a new text file with the extention 1. this file can used for further calculation.