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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.
Scoping Within the similar scope, all the declared identifiers should be unique. So, even if their datatypes differ, the variables and parameters cannot share the similar name.
Using INNER JOIN INNER JOIN is used to retrieve the data from all tables listed based on a condition of equality listed after keyword ON. If the condition is not meet, rows ar
Procedures The procedure is a subprogram which performs a specific action. You write procedures using the syntax as shown below: PROCEDURE name [(parameter[, parameter, .
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
Comparison Operators The Comparison operators can compare one expression to another. The outcome is always true, false, or null. Usually, you use a comparison operators in condi
Iteration Schemes The bounds of a loop range can be variables, literals, variables, or expressions but must compute to integers. Below are some of the examples. As you can see t
Logical Connectives - SQL SQL's extended truth tables in which the symbol, for unknown, appears along with the usual T and F. Negation (NOT, ¬) Conjunction (
Write a query to find academics that are authors and that have only ever coauthored papers with authors from institutes in the same state as their own. List their academic number,
SQL Is a Database Language: The commands given to a DBMS by an application are written in the database language of the DBMS. The term data sublanguage is sometimes used instea
PITS Depressions in secondary cell wall is called pit. A pit present on the free cell wall surface without its partner is called Blind pit. It consists of 2 parts -
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