define primary key & secondary key?
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Answer / manoj
primary key is a key which always accept unique value.
secondary key is a key which when you are making primary key
for more than one column as primary key for retrieving of
reords.
eg.
create table tnam
(ano number,
bno number,
bname char(12),
primary key(ano,bno))
In this bno is secondary key.
Is This Answer Correct ? | 31 Yes | 18 No |
Answer / renu kakkar
PRIMARY REPRESENTS THE ROW/TUPPLE UNIQUELY WHEREAS
SECONDARY KEY REPRESENTS THE SET OF TUPPLES
EMPLOY_ID IS A PRIMARY KEY AND EMPLOY_DEPTT. IS A SECONDARY
KEY.
Is This Answer Correct ? | 3 Yes | 9 No |
what are the methods using performance tunning in sql and pl/sql
Dear All, Question for this Week Find out possible error(s) (either at compile time or at runtime) in the following PL/SQL block. State the reason(s) and correct the errors. Declare Cursor C1 is select ename, sal, comm from emp; Begin For i in C1 Loop If i.comm between 299 and 999 then Dbms_output.put_line(i.Ename || ‘ ** Good Commission’); Elsif i.comm > 999 then Dbms_output.put_line(i.Empno || ‘ ** Very Good Commission’); close C1; Else Dbms_output.put_line(i.Ename || ‘ ** ’ ||nvl(i.comm,‘O’)); End if; End Loop; End;
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