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GOTO StatementThe GOTO statement branches to a label unconditionally. The label must be exclusive within its scope and should precede an executable statement or a PL/SQL block. If executed, the GOTO statement transfers control to the labeled statement or block. In the following illustration, you go to an executable statement farther down in a series of statements:BEGIN...GOTO insert_row;...<>INSERT INTO emp VALUES...END;In the next illustration, you go to a PL/SQL block farther up in a series of statements:BEGIN...<>BEGINUPDATE emp SET ......END;...GOTO update_row;...END;The label end_loop in the example below is illegal as it does not precede an executable statement:DECLAREdone BOOLEAN;BEGIN...FOR i IN 1..50 LOOPIF done THENGOTO end_loop;END IF;...<> -- illegalEND LOOP; -- not an executable statementEND;To debug the last illustration, now add the NULL statement, as shown:FOR i IN 1..50 LOOPIF done THENGOTO end_loop;END IF;...<>NULL; -- an executable statementEND LOOP;As the following illustration shows, a GOTO statement can branch to an enclosing block from the present block:DECLAREmy_ename CHAR(10);BEGIN<>SELECT ename INTO my_ename FROM emp WHERE...BEGIN...GOTO get_name; -- branch to enclosing blockEND;END;RestrictionsSome likely destinations of a GOTO statement are illegal. Particularly, a GOTO statement cannot branch into an IF statement, LOOP statement, or sub-block. For illustration, the following GOTO statement is illegal:BEGIN...GOTO update_row; -- illegal branch into IF statement...IF valid THEN...<>UPDATE emp SET...END IF;END;A GOTO statement also cannot branch from one IF statement clause to another, as the following illustration shows:BEGIN...IF valid THEN...GOTO update_row; -- illegal branch into ELSE clauseELSE...<>UPDATE emp SET...END IF;END;The next illustration shows that a GOTO statement cannot branch from an enclose block into a sub-block:BEGIN...IF status = ’OBSOLETE’ THENGOTO delete_part; -- illegal branch into sub-blockEND IF;...BEGIN...<>DELETE FROM parts WHERE...END;END;A GOTO statement also cannot branch out of a subprogram, as the following illustration shows:DECLARE...PROCEDURE compute_bonus (emp_id NUMBER) ISBEGIN...GOTO update_row; -- illegal branch out of subprogramEND;BEGIN...<>UPDATE emp SET...END;Finally, the GOTO statement cannot branch from an exception handler into the present block. For illustration, the following GOTO statement is illegal:DECLARE...pe_ratio REAL;BEGIN...SELECT price / NVL(earnings, 0) INTO pe_ratio FROM ...<>INSERT INTO stats VALUES (pe_ratio, ...);EXCEPTIONWHEN ZERO_DIVIDE THENpe_ratio := 0;GOTO insert_row; -- illegal branch into current blockEND;Though, a GOTO statement can branch from an exception handler into the enclosing block.
1.( /5 marks) Suppose that a B+-tree index with the search key (dept_name, building) is available on relation department. What would be the best way to handle the following selecti
Keyword & Parameter Description: PRAGMA: These keywords signify that the statement is a pragma (i.e. compiler directive). The Pragmas are processed at the compile time, n
Extension and AND in SQL The theory book gives the following simple example of relational extension in Tutorial D: EXTEND IS_CALLED ADD ( FirstLetter ( Name ) AS Initial )
Semidifference via EXCEPT and JOIN - SQL SELECT * FROM (SELECT StudentId FROM IS_CALLED WHERE Name = 'Devinder' EXCEPT DISTINCT CORRESPONDING SELECT StudentId
Parameter Modes: You do not require to specify a parameter mode for the input bind arguments (those used, for illustration, in the WHERE clause) as the mode defaults to IN. Th
SQL outer join SELECT * FROM IS_CALLED NATURAL LEFT JOIN IS_ENROLLED_ON Note that adding LEFT to an invocation of CROSS JOIN has no effect unless the right-hand operand
Using %ROWTYPE The %ROWTYPE attribute gives a record type which represents a row in a table (or view). The record can store the whole row of data selected from the table or fetc
Advantages of Exceptions Using the exceptions for the error handling has many benefits. Without an exception handling, every time you issue a command, you should ensure for th
Data Types in SQL - Integer INTEGER or synonymously INT, for integers within a certain range. SQL additionally has types SMALLINT and BIGINT for certain ranges of integers. T
Effects of NULL in Aggregate Operator - SQL Let aggop(x) be an invocation of some aggregate operator aggop in SQL, where x is an expression (usually an open expression) to be
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