Answer / vivek

Anti-joins:
Anti-joins are written using the NOT EXISTS or NOT IN
constructs. An anti-join between two tables returns rows
from the first table for which there are no corresponding
rows in the second table. In other words, it returns rows
that fail to match the sub-query on the right side.

Suppose you want a list of departments with no employees.
You could write a query like this:
SELECT d.department_name
FROM departments d
MINUS
SELECT d.department_name
FROM departments d, employees e
WHERE d.department_id = e.department_id
ORDER BY department_name;

The above query will give the desired results, but it might
be clearer to write the query using an anti-join:
SELECT d.department_name
FROM departments d
WHERE NOT EXISTS (SELECT NULL
FROM employees e
WHERE e.department_id = d.department_id)
ORDER BY d.department_name;

what is a primary key? : Sql dba

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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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What are the qualities of 2nf?

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What found sql?

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What is the difference between SQL table and the PLSQL table?

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what is ref cursor in pl/sql?

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