Effects of null for unique specification - sql, PL-SQL Programming

Assignment Help:

Effects of NULL for UNIQUE Specification

When a UNIQUE specification u for base table t includes a column c that is not subject to a NOT NULL constraint, the appearance of several rows having NULL in place of a value for c and equal values for the other columns specified in u is permitted. It is only when each column of the specified "key" has a value that those column values may not appear in the same combination in more than one row of t.


Related Discussions:- Effects of null for unique specification - sql

Dbms, DBMS: The answer to this question is of course given in of the t...

DBMS: The answer to this question is of course given in of the theory book. This book is concerned with SQL DBMSs and SQL databases in particular. Soon we will be looking a

Heap sort algorithm in pl sql, I want to implement heap sort algorithm in p...

I want to implement heap sort algorithm in pl sql please share the source code for guidance

Write a pl/sql anonymous block that accepts an employee id, Based on the EM...

Based on the EMPLOYEE table created in Assignment #1, write a PL/SQL anonymous block that accepts an employee ID from the user input and finds whether the employee ID is in the EMP

Manipulating local collections - pl/sql, Manipulating Local Collections ...

Manipulating Local Collections Within PL/SQL, to manipulate the local collection, by using the  TABLE and CAST operators . The operands of CAST are a collection declared locally

Pl/sql engine, Architecture The PL/SQL run-time system and compilation ...

Architecture The PL/SQL run-time system and compilation is a technology, not an independent product. Consider this technology as an engine that compiles and executes the PL/SQL

Perform exception handling with user-defined errors, On occasion, some of B...

On occasion, some of Brewbean's customers mistakenly leave an item out of a basket already checked out, so they create a new basket containing the missing items. However, they requ

Character types in pl/sql, Character Types The Character types allow yo...

Character Types The Character types allow you to store alphanumeric data, represent words and text, and manipulate the character strings. CHAR You use the CHAR dataty

Example of table literal - sql, Example of Table Literal - SQL Exampl...

Example of Table Literal - SQL Example: A Table Literal (correct version) VALUES ('S1', 'C1', 'Anne'), ('S1', 'C2', 'Anne'), ('S2', 'C1', 'Boris'), ('S3', 'C3'

How exceptions propagate in pl/sql programming?, How Exceptions Propagate ?...

How Exceptions Propagate ? Whenever an exception is raised, and if the PL/SQL cannot find a handler for it in the present subprogram or block, the exception propagates. That is

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