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Oracle Interview Questions And Answers
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Some composite data types such as RECORD & TABLE. 6. What are % TYPE and % ROWTYPE ? What are the advantages of using these over datatypes? % TYPE provides the data type of a variable or a database column to that variable. % ROWTYPE provides the record type that represents a entire row of a table or view or columns selected in the cursor. The advantages are : I. Need not know about variable's data type ii. If the database definition of a column in a table changes, the data type of a variable changes accordingly. 7. What is difference between % ROWTYPE and TYPE RECORD ? % ROWTYPE is to be used whenever query returns a entire row of a table or view. TYPE rec RECORD is to be used whenever query returns columns of different table or views and variables. E.g. TYPE r_emp is RECORD (eno emp.empno% type,ename emp ename %type ); e_rec emp% ROWTYPE cursor c1 is select empno,deptno from emp; e_rec c1 %ROWTYPE. 8. What is PL/SQL table ? Objects of type TABLE are called "PL/SQL tables", which are modelled as (but not the same as) database tables, PL/SQL tables use a primary PL/SQL tables can have one column and a primary key. Cursors 9. What is a cursor ? Why Cursor is required ? Cursor is a named private SQL area from where information can be accessed. Cursors are required to process rows individually for queries returning multiple rows. 10. Explain the two type of Cursors ? There are two types of cursors, Implict Cursor and Explicit Cursor. PL/SQL uses Implict Cursors for queries. User defined cursors are called Explicit Cursors. They can be declared and used. 11. What are the PL/SQL Statements used in cursor processing ? DECLARE CURSOR cursor name, OPEN cursor name, FETCH cursor name INTO or Record types, CLOSE cursor name. |