| queries [message #289] |
Sun, 03 February 2002 23:19  |
Raj
Messages: 411
Registered: November 1998
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Senior Member |
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what is normalisation?
what is the difference between the 1st,2nd and 3rd normalisation form?
why should we use a cursor instead of normal sql statement?
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| Re: queries [message #295 is a reply to message #289] |
Mon, 04 February 2002 03:47  |
Suresh Vemulapalli
Messages: 624
Registered: August 2000
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Senior Member |
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see rdbms concepts manual for clarification of first 2 questions.
cursor is used to process multi row returned queries. if your query returns more than one row, pl/sql engine raises predeifined exception (too_many_rows).
example:
declare
l_empno number;
begin
select empno into l_empno from emp;
dbms_output.put_line(l_empno);
end;
above program fails if emp table contains more than one record.
if you want to execute with out error...
declare
cursor c1 is select empno from emp;
l_empno number;
begin
for crec in c1 loop
l_empno:=crec.empno;
dbms_output.put_line(l_empno);
end loop;
end;
cursor stores retrived rows and process one by one.
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