PLSQL dynamic query

Question

I have a table A which has column A which holds table names as values. All these tables have a common column C. I need maximum value of this column

Answer 1

There is some miss match in veriables that you had used i.e.

1. declared as "c_table" but accessing as "c_table2"
2. Each table common column name is "C" but accessing as "object_ref"
3. In dynamic query use INTO keyword to store the value to your varibale

Suggestions

1. Use concat() function to prepare the query dynamically i.e. something like:

   SET @SQL := CONCAT('SELECT max(c) INTO ', c_obj, ' FROM ',c_table);

2. Steps of implementing dynamic query is:

   SET @SQL = 
   PREPARE stmt FROM @SQL;
   EXECUTE stmt;
   

Sample code:

DECLARE    
 query1 VARCHAR2(100);
 c_table VARCHAR2(40);
 c_obj VARCHAR2(20);
 CURSOR cursor_a IS
 SELECT a FROM A;  
BEGIN
OPEN cursor_a;
   LOOP
      FETCH cursor_a INTO c_table;      
      EXIT WHEN cursor_a%notfound; 
      SET @SQL := CONCAT('SELECT max(object_ref) AS c_obj INTO ', c_obj, ' FROM ',c_table);
    PREPARE stmt FROM @SQL;         
    EXECUTE stmt;    
    dbms_output.put_line('Maximum value: '|| c_table || c_obj);
   END LOOP;
CLOSE cursor_a;
END;