PCS Infotech Placement: Sample Questions 13 - 14 of 25

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Question 13

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Write in Short

Short Answer▾

Explain operator precedence in PL/SQL.

Explanation

Rules of Operator Precedence
  • Operator precedence determines the grouping of terms in an Expression.
  • When evaluating an expression containing multiple operators, highest precedence evaluated before those with lower precedence.
  • Precedence is the order in which runtime evaluates different operators in the same expression.
  • Oracle evaluates operators with equal precedence from left to right within an expression.
  • Multiplication operators have higher precedence than the addition operators.
  • Ex.
  • Here, x is 11, not 16 because of the operator ⚹ has higher precedence then +
  • So first 3 ⚹ 2 is done and then result added to 5.
  • Operators with the highest precedence appear at the top of the above table; those with the lowest precedence appear at the bottom.

Question 14

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Describe in Detail

Essay▾

PMON command is used for ________

Explanation

Understanding of Process Moniter

PMON command is used to recover failed process resources. PMON performs following functions:

  • Monitors and restarts failed dispatcher or server processes.
  • Periodically checks status of dispatcher and server processes, and restarts.
  • Registers information about the instance and dispatcher processes.
  • Oracle background process will free resources if a user process fails.
  • Always running for an instance.
  • Registers information about the instance and dispatcher processes with the network listener.

The background process PMON cleans up after failed processes by:

  • Rolling back the user՚s current transaction
  • Releasing all currently held table or row locks
  • Freeing other resources currently reserved by the user
  • Restarts dead dispatchers

Developed by: