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PL/SQL Exceptions

PL/SQL Exceptions. Session - III. ERROR HANDLING. Runtime errors arise from design faults, Coding mistakes , Hardware failures and many other sources. We can plan to handle certain kinds of errors meaningful to your program. Exception.

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PL/SQL Exceptions

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  1. PL/SQL Exceptions Session - III

  2. ERROR HANDLING • Runtime errors arise from design faults, Coding mistakes , Hardware failures and many other sources. • We can plan to handle certain kinds of errors meaningful to your program.

  3. Exception • In PL/SQL , warning or error message is called an Exception. • Exception can be Internally defined or User defined

  4. Types of Exceptions • Predefined Exceptions • User-defined Exceptions

  5. Predefined Exception An Internal exception is raised implicitly whenever your PL/SQL program violates an ORACLE rule or exceeds a System-dependent limit.

  6. Every ORACLE error has a number , but exceptions must be handled by name. • So PL/SQL predefines some common ORACLE errors as Exceptions.

  7. Exception Names • NO_DATA_FOUND • TOO_MANY_ROWS • VALUE_ERROR • CURSOR_ALREADY_OPEN • INVALID_NUMBER

  8. Exception Names • INVALID_CURSOR • STORAGE_ERROR • PROGRAM_ERROR • DUP_VAL_ON_INDEX • ZERO_DIVIDE

  9. No_Data_Found This exception will be raised if the PL/SQL select statement fetches no records

  10. Too_many_Rows This exception is raised when the PL/SQL select statement fetches more than One record

  11. Invalid Cursor This exception will fire when trying to fetch records or close the cursor which is not opened.

  12. Cursor_Already_Open This exception is raised when trying to the open the same cursor without closing it.

  13. Value_Error This exception will be raised if there is a data type mismatch or sizing error in the PL/SQL program.

  14. Invalid_Number This exception will be raised when improper conversion of data type takes place in the SQL.

  15. STORAGE_Error This exception will be raised only if there is a RAM Overflow. 99% this error will not occur

  16. No Data Found Declare enam emp.ename%type; Begin Select ename INTO enam from emp where empno=7368; Exception When No_Data_Found then Dbms_output.put_line(‘No Such Record’); End;

  17. Too_many_rows Declare enam emp.ename%type; Begin Select ename INTO enam from emp where empno In (7368,7369) ; Exception When too_many_rows then Dbms_output.put_line(‘More than 1 row fetched’); End;

  18. User- Defined Exceptions • PL/SQL lets you define exceptions of your own. • Must be declared and must be raised explicitly by RAISE Statement

  19. Declaring Exceptions • Can be declared only in the Declarative part of a PL/SQL block, Sub program. • Declare an Exception by a Name followed by the keyword EXCEPTION Declare first Exception; ename Varchar(15); Begin

  20. How Exceptions are Raised PredefinedException are Raised Implicitly by the Runtime. User-Defined must be raised Explicitly by RAISE Statement.

  21. Declare first Exception; ename Varchar(15); Begin Update emp set sal=sal+1000 where empno=90; if SQL%notfound then Raise first; End if; Exception When First then Dbms_output.put_line(‘no match ‘); End ;

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