Consider the following one-dimensional ARRAY data type and table.
CREATE TYPE phonenumbers AS VARRAY(20) OF CHAR(10); CREATE TABLE employee_info (eno INTEGER, phonelist phonenumbers);
The table is populated with the following values:
/* The first 2 elements are populated; the rest are uninitialized. */ INSERT INTO employee_info VALUES (1, phonenumbers('1112223333', '6195551234')); /* Empty ARRAY instance */ INSERT INTO employee_info VALUES (2, phonenumbers()); /* Update the empty ARRAY instance such that element 3 is set to a value; then elements 1 and 2 are set to NULL, the rest are uninitialized. */ UPDATE employee_info SET phonelist[3] = '8584850000' WHERE id = 2;
The following query checks to see whether element 2 of the phonelist array contains a value.
SELECT eno, phonelist.OEXISTS(2) FROM employee_info;
The following is the result of the query.
ENO phonelist.OEXISTS(2) --- -------------------- 1 1 (element 2 contains a value that is non-NULL) 2 1 (element 2 contains a NULL)
The following query checks to see whether element 3 of the phonelist array contains a value.
SELECT eno, phonelist.OEXISTS(3) FROM employee_info;
The following is the result of the query.
ENO phonelist.OEXISTS(3) --- -------------------- 1 0 (element 3 is in an uninitialized state) 2 1 (element 3 contains a value that is non-NULL)
The following is the same query using function-style syntax.
SELECT eno, OEXISTS(phonelist, 3) FROM employee_info;