MERGE: unexpected behaviour, oracle 11g

Question

Hi all,
I'm facing a strange behaviour with Merge statement.
In particular in doc Oracle we read:
"MERGE is a deterministic statement. That is, you +*cannot update*+ the same row of the target table multiple times in the same MERGE statement."
My source table has two equal key rows and the "merge statement" merge the row with the last value in the source table.
How Is this possible ?
thank you.

Answer 1

VERSION:
SQL> select * from v$version
  2  ;
BANNER
Oracle Database 11g Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for 64-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
SQL>MERGE, in a dynamic context:
v_sql :=
'MERGE INTO dwh_cdl.dim_cost_hierarchy dim
         USING (SELECT DISTINCT TRIM (item_code) id_item,
                                NVL (TRIM (CATEGORY), ''ND'') CATEGORY,
                                r1.r1_code r_1,
                                r2.r2_code r_2,
                                r3.r3_code r_3,
                                r4.r4_code r_4,
                                w.item_description desc_item
                                        FROM '
                                        || v_wrk
                                        || ' w INNER JOIN dwh_cdl.lu_r1 r1
                                             ON (w.r_1 = r1.r1_code)
                                             INNER JOIN dwh_cdl.lu_r2 r2
                                             ON (w.r_2 = r2.r2_code)
                                             INNER JOIN dwh_cdl.lu_r3 r3
                                             ON (w.r_3 = r3.r3_code)
                                             INNER JOIN dwh_cdl.lu_r4 r4
                                             ON (w.r_4 = r4.r4_code)
                                ) wrk
         ON (    dim.id_item = wrk.id_item
             AND dim.category = wrk.category
             AND dim.r1_code = wrk.r_1
             AND dim.r2_code = wrk.r_2
             AND dim.r3_code = wrk.r_3
             AND dim.r4_code = wrk.r_4
             AND dim.wid_country = '
            || pkg_global.v_country
            || ')
         WHEN MATCHED THEN
            UPDATE
               SET dim.desc_item = wrk.desc_item
         WHEN NOT MATCHED THEN
            INSERT (wid_item, id_item, CATEGORY, desc_item, type_item,
                    flag_valid, r1_code, r2_code, r3_code, r4_code,
                    wid_country, date_in)
            VALUES (pkg_util.get_next_val (''DIM_COST_HIERARCHY''), wrk.id_item,
                    wrk.CATEGORY, wrk.desc_item, NULL, 1, r_1, r_2, r_3, r_4,
            || pkg_global.v_country
            || ', SYSDATE)';
EXECUTE IMMEDIATE v_sql;The USING table has duplicate key rows. So when join with "dim_cost_hierarchy" Oracle should issue error ! But, it doesn't !
It gets the last one row value.