Oracle : how to fetch data from dynamic query? - sql

Question

I have a program to generate dynamic query string based on input. This query may select from any tables or joined tables in my DB, and the column names and number of columns are unknown.
Now with this query string as the only input, I want to fetch all data from the result and output them line by line, is there any way to do this ?
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Thank Thinkjet for the reference. I have solved the problem, to help the others, here is the piece of code I used:
DECLARE
v_curid NUMBER;
v_desctab DBMS_SQL.DESC_TAB;
v_colcnt NUMBER;
v_name_var VARCHAR2(10000);
v_num_var NUMBER;
v_date_var DATE;
v_row_num NUMBER;
p_sql_stmt VARCHAR2(1000);
BEGIN
v_curid := DBMS_SQL.OPEN_CURSOR;
p_sql_stmt :='SELECT * FROM emp';
DBMS_SQL.PARSE(v_curid, p_sql_stmt, DBMS_SQL.NATIVE);
DBMS_SQL.DESCRIBE_COLUMNS(v_curid, v_colcnt, v_desctab);
-- Define columns:
FOR i IN 1 .. v_colcnt LOOP
IF v_desctab(i).col_type = 2 THEN
DBMS_SQL.DEFINE_COLUMN(v_curid, i, v_num_var);
ELSIF v_desctab(i).col_type = 12 THEN
DBMS_SQL.DEFINE_COLUMN(v_curid, i, v_date_var);
ELSE
DBMS_SQL.DEFINE_COLUMN(v_curid, i, v_name_var, 50);
END IF;
END LOOP;
v_row_num := dbms_sql.execute(v_curid);
-- Fetch rows with DBMS_SQL package:
WHILE DBMS_SQL.FETCH_ROWS(v_curid) > 0 LOOP
FOR i IN 1 .. v_colcnt LOOP
IF (v_desctab(i).col_type = 1) THEN
DBMS_SQL.COLUMN_VALUE(v_curid, i, v_name_var);
ELSIF (v_desctab(i).col_type = 2) THEN
DBMS_SQL.COLUMN_VALUE(v_curid, i, v_num_var);
ELSIF (v_desctab(i).col_type = 12) THEN
DBMS_SQL.COLUMN_VALUE(v_curid, i, v_date_var);
END IF;
END LOOP;
END LOOP;
DBMS_SQL.CLOSE_CURSOR(v_curid);
END;
/

Answer 1

You can do that with DBMS_SQL package.
Update
To get more detailed reference about DBMS_SQL go here.

Answer 2

If you are building your string within PL/SQL, you can run it with EXECUTE IMMEDIATE. <- link. Use the BULK COLLECT INTO and output the collection.

Answer 3

<PRE>
DECLARE
RUN_S CLOB;
IGNORE NUMBER;
SOURCE_CURSOR NUMBER;
PWFIELD_COUNT NUMBER DEFAULT 0;
L_DESCTBL DBMS_SQL.DESC_TAB2;
Z_NUMBER NUMBER;
BEGIN
RUN_S := ' SELECT 1 AS VAL1,
2 AS VAL2,
CURSOR (SELECT 11 AS VAL11,
12 AS VAL12
FROM DUAL) AS CUR1,
CURSOR (SELECT 11 AS VAL11,
12 AS VAL12
FROM DUAL) AS CUR2
FROM DUAL';
SOURCE_CURSOR := DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE(SOURCE_CURSOR, RUN_S, DBMS_SQL.NATIVE);
DBMS_SQL.DESCRIBE_COLUMNS2(SOURCE_CURSOR, PWFIELD_COUNT, L_DESCTBL); -- get record structure
FOR I IN 1 .. PWFIELD_COUNT LOOP
DBMS_OUTPUT.PUT_LINE('Col ' || I || ' Type:' || L_DESCTBL(I).COL_TYPE);
IF L_DESCTBL(I).COL_TYPE = 2 THEN
DBMS_SQL.DEFINE_COLUMN(SOURCE_CURSOR, I, Z_NUMBER);
END IF;
NULL;
END LOOP;
IGNORE := DBMS_SQL.EXECUTE(SOURCE_CURSOR);
LOOP
IF DBMS_SQL.FETCH_ROWS(SOURCE_CURSOR) > 0 THEN
FOR I IN 1 .. PWFIELD_COUNT LOOP
IF L_DESCTBL(I).COL_TYPE IN (2) THEN
DBMS_SQL.COLUMN_VALUE(SOURCE_CURSOR, I, Z_NUMBER);
DBMS_OUTPUT.PUT_LINE('Col ' || I || ' Value:' || Z_NUMBER);
END IF;
END LOOP;
ELSE
EXIT;
END IF;
END LOOP;
END;
</PRE>