Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
WHILE-LOOPThe WHILE-LOOP statement relates a condition with the series of statements enclosed by the keywords LOOP and END LOOP, as shown:WHILE condition LOOPsequence_of_statementsEND LOOP;Before each of the iteration of the loop, the condition is computed. If the condition is true, then the series of statements is executed, then the control resumes at the top of the loop. When the condition is false or null, the loop is then bypassed and control passes to the next statement. An illustration is shown below:WHILE total <= 25000 LOOP...SELECT sal INTO salary FROM emp WHERE...total := total + salary;END LOOP;The number of iterations depends on the condition and is not known until the loop done. The condition is tested at the top of the loop, so the series might execute zero times. In the last illustration, if the initial value of total is bigger than 25000, the condition is false and the loop is bypassed.A few languages have a LOOP UNTIL or REPEAT UNTIL structure, that tests the condition at the bottom of the loop rather than at the top. So, the sequence of the statements is executed at least once. The PL/SQL has no such structure, but you can easily build one, as shown:LOOPsequence_of_statementsEXIT WHEN boolean_expression;END LOOP;To make sure that a WHILE loop executes at least once, then use an initialized Boolean variable in the condition which is as shown below:done := FALSE;WHILE NOT done LOOPsequence_of_statementsdone := boolean_expression;END LOOP;The statement inside the loop should assign a new value to the Boolean variable. Or else, you have an infinite loop. For illustration, the following LOOP statements are logically equal:WHILE TRUE LOOP | LOOP... | ...END LOOP; | END LOOP;
Opening a Cursor Opening the cursor executes the query & identifies the result set that consists of all rows that meet the query search criteria. For the cursors declared usin
Declaring a Cursor The Forward references are not allowed in the PL/SQL. Therefore, you must declare a cursor before referencing it in other statements. Whenever you declare a
Example of NOT EXISTS in SQL Example: Use of NOT EXISTS CREATE ASSERTION Must_be_enrolled_to_take_exam_alternative1 CHECK ( NOT EXISTS (SELECT StudentId, CourseId
Semijoin and Composition - SQL For semijoin, the dyadic relational operator MATCHING, defined thus: r1 MATCHING r2, where r1 and r2 are relations such that r1 JOIN r2 is de
DELETE Command - SQL Loosely speaking, DELETE removes some existing rows from its target table. Suppose the university decides that course C3 is to be withdrawn. Example shows
Cursor Attributes The Cursors and cursor variables have 4 attributes which give you helpful information about the execution of a data manipulation statement. Syntax:
Updating Variables For assignment, SQL uses the key word SET, as in SET X = X + 1 (read as "set X equal to X+1") rather than X: = X + 1 as found in many computer languages.
Aggregate Assignment The %ROWTYPE declaration cannot include an initialization clause. Though, there are two ways to assign values to all fields in a record at once. At First, t
Defining REF CURSOR Types To make cursor variables, you take 2 steps. At first, you define a REF CURSOR type, and then declare the cursor variables of that type. You can defin
Positional and Named Notation You can write the actual parameters when calling a subprogram, using either positional or named notation. That is, you can point to the relationsh
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!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd