The Difference between Explicit and Implicit Cursors : Implicit Cursor « Cursor « Oracle PL/SQL Tutorial





SQL>
SQL> -- create demo table
SQL> create table Employee(
  2    ID                 VARCHAR2(4 BYTE)         NOT NULL,
  3    First_Name         VARCHAR2(10 BYTE),
  4    Last_Name          VARCHAR2(10 BYTE),
  5    Start_Date         DATE,
  6    End_Date           DATE,
  7    Salary             Number(8,2),
  8    City               VARCHAR2(10 BYTE),
  9    Description        VARCHAR2(15 BYTE)
 10  )
 11  /

Table created.

SQL>
SQL> -- prepare data
SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2               values ('01','Jason',    'Martin',  to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto',  'Programmer')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('02','Alison',   'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('03','James',    'Smith',   to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('04','Celia',    'Rice',    to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('05','Robert',   'Black',   to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('06','Linda',    'Green',   to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York',  'Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('07','David',    'Larry',   to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York',  'Manager')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('08','James',    'Cat',     to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
  3  /

1 row created.

SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
  2  /

ID   FIRST_NAME LAST_NAME  START_DAT END_DATE      SALARY CITY       DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01   Jason      Martin     25-JUL-96 25-JUL-06    1234.56 Toronto    Programmer
02   Alison     Mathews    21-MAR-76 21-FEB-86    6661.78 Vancouver  Tester
03   James      Smith      12-DEC-78 15-MAR-90    6544.78 Vancouver  Tester
04   Celia      Rice       24-OCT-82 21-APR-99    2344.78 Vancouver  Manager
05   Robert     Black      15-JAN-84 08-AUG-98    2334.78 Vancouver  Tester
06   Linda      Green      30-JUL-87 04-JAN-96    4322.78 New York   Tester
07   David      Larry      31-DEC-90 12-FEB-98    7897.78 New York   Manager
08   James      Cat        17-SEP-96 15-APR-02    1232.78 Vancouver  Tester

8 rows selected.

SQL>
SQL>
SQL>
SQL> -- Explicit cursor
SQL>
SQL> create or replace function f_empExp_dsp (i_empNo VARCHAR)
  2  return VARCHAR2 is
  3      v_out_tx VARCHAR2(2000);
  4      cursor c_emp (ci_empNo VARCHAR) is
  5        select id||' '||first_Name||' ('|| city ||')' emp_dsp
  6         from employee
  7         where id=ci_empNo;
  8
  9      v_emp_rec  c_emp%ROWTYPE;
 10  begin
 11      open c_emp(i_empNo);
 12      fetch c_emp into v_emp_rec;
 13      close c_emp;
 14      return v_emp_rec.emp_dsp;
 15  exception
 16      when others then
 17          if c_emp%ISOPEN then
 18              close c_emp;
 19          end if;
 20          return null;
 21  end f_empExp_dsp;
 22  /

Function created.

SQL>
SQL> -- Implicit cursor
SQL> create or replace function f_empImp_dsp(in_empNo VARCHAR)
  2  return VARCHAR2 is
  3      v_out_tx VARCHAR2(2000);
  4  begin
  5      select id||' '||first_Name||' ('||city||')' into v_out_tx
  6       from employee
  7       where id=in_empNo;
  8      return v_out_tx;
  9  exception
 10      when no_data_found then
 11          return null;
 12      when too_many_rows then
 13          return '<Error>';
 14  end f_empImp_dsp;
 15  /

Function created.

SQL>
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
  2  /

Table dropped.

Explicit cursors do not raise the exceptions NO_DATA_FOUND and TOO_MANY_ROWS.

To store a fetched value, you can reference an explicit cursor with %ROWTYPE.











25.8.Implicit Cursor
25.8.1.Taking a Shortcut with CURSOR FOR Loops
25.8.2.%ISOPEN, %FOUND, %NOTFOUND variables aren't useful at all in CURSOR FOR loops
25.8.3.Implicit Cursor Attributes: SQL%NOTFOUND
25.8.4.Implicit Cursor Attributes Example: SQL%ROWCOUNT
25.8.5.NO_DATA_FOUND Exception vs. %NOTFOUND
25.8.6.Looping through a Cursor by Using the LOOP Command
25.8.7.Adding an Exception Handler to a CURSOR FOR Loop
25.8.8.Knowing what record is processing
25.8.9.Use %ROWCOUNT to detect what record you are processing at a given point
25.8.10.Declare and use a cursor in for loop
25.8.11.Implicit cursor open, fetch and close
25.8.12.Handling exceptions in implicit cursors
25.8.13.Returning an implicit cursor into a record
25.8.14.The Difference between Explicit and Implicit Cursors
25.8.15.Implicit Cursor: Too many rows
25.8.16.Implicit Cursor: No rows found
25.8.17.Use implicit or explicit cursor to insert 50000 rows to a table
25.8.18.Test cursor attributes with an implicit cursor