PL / SQL动态SQL

Question

I need help. I have a problem in constructing my PL/SQL block. In the cursor, I have a query constructed, and i want to insert a filter on cursor. Below is an example:

DECLARE 
code NUMBER;
parameters_amb myOthertable%ROWTYPE;

CURSOR test is SELECT id from mytable
 if parameters_amb.test2 is not null  then
    where mytable.name = 'NAMETABLE'
 else
    where mytable.name = 'NAMETABLE2';

Can anyone assist me in this construction?

Answer 1

You can use a parameterized cursor:

DECLARE 
code NUMBER;
parameters_amb myOthertable%ROWTYPE;
param mytable.name%TYPE;

CURSOR test (p_name VARCHAR2) is 
  SELECT id 
    FROM mytable
   WHERE mytable.name = p_name;
BEGIN
  if parameters_amb.test2 is not null  then
    param := 'NAMETABLE'
  else
    param := 'NAMETABLE2';
  end if;

  OPEN test(param);

  -- Add code to fetch and read from cursor
END;

Answer 2

DECLARE
 stmt varchar2(1000);
 code NUMBER;
 parameters_amb myOthertable%ROWTYPE;
BEGIN
 stmt := 'SELECT id from mytable';
 if parameters_amb.test2 is not null  
 then
    stmt := stmt||' where mytable.name = ''NAMETABLE''';
 else
    stmt := stmt||' where mytable.name = ''NAMETABLE2''';
 end if;

 OPEN test FOR stmt;
...
...
END;

Answer 3

You can try it like this:

DECLARE  
  code NUMBER; 
  parameters_amb myOthertable%ROWTYPE;  
  CURSOR test is SELECT id 
                 from mytable  
                 WHERE (parameters_amb.test2 is not null AND mytable.name = 'NAMETABLE' )
                   OR (parameters_amb.test2 is null AND mytable.name = 'NAMETABLE2' );

Or like this:

DECLARE  
  code NUMBER; 
  parameters_amb myOthertable%ROWTYPE;  
  CURSOR test is SELECT id 
                 from mytable  
                 WHERE mytable.name = 
                       CASE WHEN parameters_amb.test2 is not null THEN 'NAMETABLE'
                            WHEN parameters_amb.test2 is null THEN 'NAMETABLE2' END

Answer 4

Here is a simple solution:

DECLARE code NUMBER; parameters_amb myOthertable%ROWTYPE;

CURSOR test is SELECT id from mytable where mytable.name = NVL2(parameters_amb.test2, 'NAMETABLE', 'NAMETABLE2');