PL

Nested table

In PL SQL exists an efficient and adaptable collection of data: Nested table. Nested table is similar to one dimensional array but with some differences : An array has declare number of element – Nested table not. The size of nested table can increase using extend method. An array has always consecutive elements – Nested table has consecutive elements initially but it can become sparse when elements are deleted. To create a nested table you have to use this syntax : type type_name is table of element_type[size element]; table_name type_name; Here below an example to creation and use of a Read More

Binary Search

One of the most interesting algorithms of research is binary search algorithm. This is the fastest algorithm (algorithm of binary trees apart) to search a data inside a group of elements. In fact it runs in a worst log2(x) comparisions before to find (or not) the data. The only prerequisite is : the set of elements where to search the data must be sorted. Below an example of this algorithm. int binary_search( int arr[], int tot_el, int data ) { /* Declaration and initialization of variables */ int el = 0; int me = 0; int count = 0; /* Read More

Create an Index By Table of Record

An index by table is an associative array. An associative array never has more than two columns: the variable being indexes and the index value. However you can combine a record with an associative array to tie multiple values to the same index.   In this case the array still has a variable and an index, but the record variable now contains multiple distinct values. In the below example you’ll see how to associate a record to an associative array.   DECLARE   TYPE r_impiegati IS RECORD (                         Read More