Unnest operator in sql, PL-SQL Programming

Assignment Help:

UNNEST operator in SQL

The inverse operator of GROUP is UNGROUP. SQL has an operator, UNNEST, that can be used for similar purposes, but its method of invocation is somewhat peculiar, as Example shows, and it can be used only to specify a FROM clause element.

Example: Inverse operator of GROUP by using UNNEST

SELECT DISTINCT * FROM C_ER2, UNNEST ( ExamResult ) AS M

The name C_ER2 could be defined using a WITH clause. Notice how the second element of the FROM clause has to be reevaluated for each row of C_ER2, whereas each FROM clause element is normally evaluated just once because its value does not vary from row to row of previous elements. The column reference ExamResult is a reference to the column of that name in C_ER2 and is permitted only because C_ER2 is specified before UNNEST (ExamResult) in the FROM clause-a switching of these two FROM clause elements would result in a syntax error.


Related Discussions:- Unnest operator in sql

Keyword and parameter description in pl sql, Keyword and Parameter Descript...

Keyword and Parameter Description: label_name: This is an undeclared identifier which optionally labels the PL/SQL block. When used, label_name should be enclosed by the do

Parameter aliasing, Parameter Aliasing   To optimize the subprogram ca...

Parameter Aliasing   To optimize the subprogram call, the PL/SQL compiler can decide between the two techniques of the parameter passing. With the by-value techniques, the v

Row counterparts of table operators - sql, Row Counterparts of Table Operat...

Row Counterparts of Table Operators SQL does not have counterparts tuple rename, tuple projection, tuple extension, tuple join and tuple compose. To obtain the same effects as

Parameter and keyword description - sql cursor, Parameter and Keyword Descr...

Parameter and Keyword Description: SQL: This SQL is the name of the implicit SQL cursor. %FOUND: This attribute results TRUE if an INSERT, DELETE, or UPDATE state

Interesting properties of cross join - sql, Interesting properties of CROSS...

Interesting properties of CROSS JOIN - SQL Compare these with the "interesting properties of JOIN", CROSS JOIN is associative but not commutative. Unlike JOIN and NATURAL JOI

Updating by insertion, Updating by insertion Syntax : INSERT IN...

Updating by insertion Syntax : INSERT INTO ENROLMENT VALUES (SID ('S4'), 'Devinder', CID ('C1'));

Using %type-declarations in sql, Using %TYPE The %TYPE attribute gives th...

Using %TYPE The %TYPE attribute gives the datatype of a variable or the database column. In the example below, the %TYPE gives the datatype of a variable: credit REAL(7,2); debi

Multiset types - sql, Multiset types - SQL An SQL multiset is what in ...

Multiset types - SQL An SQL multiset is what in mathematics is also known as a bag-something like a set except that the same element can appear more than once. The body of an

Data types in sql - timestamp, Data Types in SQL - Timestamp TIMESTAMP...

Data Types in SQL - Timestamp TIMESTAMP for values representing points in time on a specified uniform scale. DATE is used for timestamps on a scale of one day, such as DATE '2

Create a procedure that update the status, Create a procedure named STATUS_...

Create a procedure named STATUS_SHIP_SP that allows a company to employee in the Shipping Department to update the status of an order to add shipping information. The BB_BASKETSTAT

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd