Dynamically Execute SQL statement stored in CLOB field with bind variables

 

  I saw many examples in the past when SQL statement was actually stored in CLOB field and programmer had to execute the statement dynamically.

All Oracle PL/SQL developers are familiar with “execute immediate” statement, but unfortunately  it cannot use CLOB field as an input.

But it is not the only way to execute the code dynamically.  Oracle also provides DBMS_SQL package that can execute the code dynamically and it can get the statement as an array data type. We will use it

   Here how you can do it.

Let assume that your SQL will be stored in the following variable

l_stmt         CLOB;

Now we need to split the CLOB to chunks that will became a member of array I mentioned previously

v_upperbound NUMBER;

This is array definition

v_sql        DBMS_SQL.VARCHAR2S;

Calculate array length

v_upperbound := CEIL(DBMS_LOB.GETLENGTH(l_stmt)/256);

Fill array members:

FOR i IN 1..v_upperbound
LOOP
         v_sql(i) := DBMS_LOB.SUBSTR(l_stmt
                                  ,256 -- amount
                                  ,((i-1)*256)+1 -- offset
                                  );
END LOOP;

 

Create new cursor:

v_cur        INTEGER;

v_cur := DBMS_SQL.OPEN_CURSOR;

 

Prepare your statement for execution , but parsing array members

DBMS_SQL.PARSE(v_cur, v_sql, 1, v_upperbound, FALSE, DBMS_SQL.NATIVE);

You can also use bind variables at this point

dbms_sql.bind_variable( v_cur, ':USER_NAME', ‘SYSADMIN’);

All what is left is to execute the statement

v_ret        NUMBER;

v_ret := DBMS_SQL.EXECUTE(v_cur);

 

Bellow if full example that uses approach described above

declare

  l_stmt       CLOB;
  v_upperbound NUMBER;
  v_cur        INTEGER;
  v_sql        DBMS_SQL.VARCHAR2S;
  v_ret        NUMBER;

begin
   -- get sql statement into CLOB
  select statement
    into l_stmt
    from XX_NEW_STATEMENTS_V --some view that holds CLOB 
                                         --with SQL
   where statement_type = 'SETUP'
     and seq_num = 10;

  v_upperbound := CEIL(DBMS_LOB.GETLENGTH(l_stmt) / 256);

  FOR i IN 1 .. v_upperbound LOOP
    v_sql(i) := DBMS_LOB.SUBSTR(l_stmt, -- clob statement
                                256,     -- amount
                                ((i - 1) * 256) + 1 
                                );
  END LOOP;
        
  v_cur := DBMS_SQL.OPEN_CURSOR;
        -- parse sql statement
  DBMS_SQL.PARSE(v_cur, v_sql, 1, v_upperbound, FALSE, DBMS_SQL.NATIVE);
        -- use bind variable if you need
  dbms_sql.bind_variable(v_cur, ':USER_ID', 235341);
  -- execute
  v_ret := DBMS_SQL.EXECUTE(v_cur);

end;