15.00 - OPRIOR - Teradata Database

OPRIOR

Purpose  

Returns the subscript of the element prior to the element specified for array_expr, if that element is currently populated.

Syntax  

System function syntax:

Method-style syntax:

where:

Syntax element…	Specifies…
TD_SYSFNLIB	the name of the database where the method is located.
array_expr	an ARRAY expression, which is one of the following: A reference to an ARRAY column An ARRAY constructor expression. See “ARRAY Constructor Expression” on page 195. A UDF expression A UDM expression
integer_value	an unsigned INTEGER value.
array_bound	an array instance of the predefined array type ArrayVec with a comma-separated list of integer values to define the bounds. For details, see “ARRAY Scope Reference” on page 198.

ANSI Compliance

This is a Teradata extension to the ANSI SQL:2011 standard.

Usage Notes  

OPRIOR takes an array expression as an argument and returns the subscript of the element prior to the element specified by integer_value or array_bound, if that element is currently populated. If you specify an element subscript that is less than or equal to the value of OFIRST for the array, a NULL is returned. Also, if integer_value or array_bound is NULL, an error is returned.

If array_expr is a one-dimensional ARRAY type, OPRIOR returns an unsigned INTEGER value. If array_expr is a multidimensional ARRAY type, OPRIOR returns a new instance of the predefined ARRAY type ArrayVec, containing the subscript information. If the array is empty (all elements of the array are in an uninitialized state), then OPRIOR returns NULL.

If array_expr is NULL, an error is returned.

The OPRIOR method with one INTEGER argument is compatible with the Oracle PRIOR method for one-dimensional ARRAY types.

Result Type

OPRIOR returns an unsigned INTEGER value or a new instance of the predefined ARRAY type ArrayVec.

Example  

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 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 returns the subscript of the element prior to element 2 in the phonelist array.

SELECT eno, phonelist.OPRIOR(2)

FROM employee_info;

The following is the result of the query.

ENO         phonelist.OPRIOR(2)

---         -------------------

 1           1

 2           1

The following is the same query using function-style syntax.

SELECT eno, OPRIOR(phonelist, 2) 

FROM employee_info;

Example  

Consider the following 2-D ARRAY data type and table.

CREATE TYPE shot_ary AS VARRAY(1:50)(1:50) OF INTEGER;

CREATE TABLE seismic_table (

   id INTEGER,

   shots shot_ary);

The table is populated with the following values:

/* The first 2 elements are populated; the rest are uninitialized. */

INSERT INTO seismic_table VALUES (1, shot_ary(11, 12));

/* Empty ARRAY instance */

INSERT INTO seismic_table VALUES (2, shot_ary());

/* Update empty ARRAY instance such that element [1][3] is set to a value; Then elements [1][1] and [1][2] are set to NULL, the rest are uninitialized */

UPDATE seismic_table

SET shots[1][3] = 1133

WHERE id = 2;

The following query returns the subscript of the element prior to element [1][2] in the shots array.

SELECT id, shots.OPRIOR(NEW arrayVec(1, 2)) 

FROM seismic_table;

The following is the result of the query.

ID          shots.OPRIOR(NEW arrayVec(1, 2))

--          --------------------------------

 1           NEW arrayVec(1,1)

 2           NEW arrayVec(1,1)