Primary key, PL-SQL Programming

PRIMARY KEY:

PRIMARY KEY  indicates that the table is subject to a key constraint, in this case declaring that no two rows in the table assigned to ENROLMENT can ever have the same combination of StudentId and CourseId fields (i.e., we cannot enrol the same student on the same course more than once, so to speak). We will learn more about SQL constraints in general and SQL's key constraints.

Posted Date: 1/11/2013 5:22:39 AM | Location : United States







Related Discussions:- Primary key, Assignment Help, Ask Question on Primary key, Get Answer, Expert's Help, Primary key Discussions

Write discussion on Primary key
Your posts are moderated
Related Questions
Advantages of Invoker Rights The Invoker-rights routines centralize the data retrieval. They are particularly helpful in applications which store data in various schemas. In su

Raise_application_error -  procedure of package DBMS_STANDARD , allows to issue an user_defined error messages by stored sub-program or database trigger.

UTL_FILE: The Package UTL_FILE permits your PL/SQL programs to read & write operating system (OS) text files. It gives a restricted version of the standard OS stream file I/O,

The Package Specification The package specifications contain the public declarations. The scopes of these declarations are local to your database representation and global to t

TYPES OF EVOLUTION - Sequential evolution                  :                    Minor changes in the gene pool of a population from one generation to the next, with the resul

Inserting Objects: You can use the INSERT statement to add objects to an object table. In the illustration below, you insert a Person object into the object table persons:

Using COMMIT The COMMIT statements end the present transaction and make permanent any changes made during that transaction. Till you commit the changes, other users cannot acc

Use Native Dynamic SQL A few programs (a normal-purpose report writer for illustration) should build and process a variety of SQL statements at run time. Therefore, their full

1. a. Write a trigger that fires when a part's price is updated. The trigger will write a record into a table called PriceUpdates. The record should contain the information of

Positional Notation The first procedure call uses the positional notation. The PL/SQL compiler relates the first actual parameter, account, with the first proper parameter, ac