Shulou(Shulou.com)05/31 Report--

This article mainly introduces "what is the judgment method that the database CLOB is empty". In the daily operation, I believe that many people have doubts about the judgment method that the database CLOB is empty. The editor consulted all kinds of materials and sorted out the simple and useful operation methods. I hope it will be helpful to answer the doubts of "what is the judgment method that the database CLOB is empty". Next, please follow the editor to study!

Which of the following options will display "CLOB has a length of 0" after execution?

(A)

DECLARE l_clob CLOB;BEGIN IF l_clob IS NULL THEN DBMS_OUTPUT.put_line ('CLOB is NULL'); ELSE DBMS_OUTPUT.put_line (' CLOB has a length of'| | LENGTH (l_clob)); END IF;END;/SQL > DECLARE 2 l_clob CLOB; 3 BEGIN 4 IF l_clob IS NULL 5 THEN 6 DBMS_OUTPUT.put_line ('CLOB is NULL') 7 ELSE 8 DBMS_OUTPUT.put_line ('CLOB has a length of' 9 | | LENGTH (l_clob)); 10 END IF; 11 END; 12 / CLOB is NULLPL/SQL procedure successfully completedSQL >

(B)

DECLARE l_clob CLOB: = EMPTY_CLOB (); BEGIN IF l_clob IS NULL THEN DBMS_OUTPUT.put_line ('CLOB is NULL'); ELSE DBMS_OUTPUT.put_line (' CLOB has a length of'| | LENGTH (l_clob)); END IF;END;/SQL > DECLARE 2 l_clob CLOB: = EMPTY_CLOB () 3 BEGIN 4 IF l_clob IS NULL 5 THEN 6 DBMS_OUTPUT.put_line ('CLOB is NULL'); 7 ELSE 8 DBMS_OUTPUT.put_line (' CLOB has a length of'9 | | LENGTH (l_clob)); 10 END IF; 11 END; 12 / CLOB has a length of 0PL/SQL procedure successfully completedSQL >

(C)

DECLARE l_clob CLOB: =''; BEGIN IF l_clob IS NULL THEN DBMS_OUTPUT.put_line ('CLOB is NULL'); ELSE DBMS_OUTPUT.put_line (' CLOB has a length of'| | LENGTH (l_clob)); END IF;END;/SQL > DECLARE 2 l_clob CLOB: ='' 3 BEGIN 4 IF l_clob IS NULL 5 THEN 6 DBMS_OUTPUT.put_line ('CLOB is NULL'); 7 ELSE 8 DBMS_OUTPUT.put_line (' CLOB has a length of'9 | | LENGTH (l_clob)); 10 END IF; 11 END; 12 / CLOB is NULLPL/SQL procedure successfully completedSQL >

(D)

DECLARE l_clob1 CLOB: = EMPTY_CLOB (); l_clob2 CLOB: = lumped clob1 + begin IF l_clob2 IS NULL THEN DBMS_OUTPUT.put_line ('CLOB is NULL'); ELSE DBMS_OUTPUT.put_line (' CLOB has a length of'| | LENGTH (l_clob2)); END IF;END;/SQL > DECLARE 2 l_clob1 CLOB: = EMPTY_CLOB () 3 l_clob2 CLOB: = lumped clob1; 4 BEGIN 5 IF l_clob2 IS NULL 6 THEN 7 DBMS_OUTPUT.put_line ('CLOB is NULL'); 8 ELSE 9 DBMS_OUTPUT.put_line (' CLOB has a length of'10 | | LENGTH (l_clob2)); 11 END IF; 12 END; 13 / CLOB has a length of 0PL/SQL procedure successfully completed

Answer BD. Notice that the''in answer C is equivalent to NULL.

At this point, the study of "what is the method of judging that the database CLOB is empty" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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