hello, I am developping a C#. application which uses Oracle 9i, I get ORA-00001(unique constraint) Error on executing the sql below; I know sql below is little strange( which use unique key in 'SET' statement) . but It worked on My Oracle Server. but it didn't on Client's. does anybody know why this error occurs or why this error did not occur on my PC, thanks, [update sql](key is CD and SDATE) Update TBL1 set CD = 'A', NAME = '1', SDATE=TO_DATE('2008-10-31 00:00', 'YYYY-MM-DD HH24:MI' ) WHERE CD = 'A' and SDATE=TO_DATE('2008-10-31 00:00', 'YYYY-MM-DD HH24:MI' ) [table definition] CREATE TABLE TBL1 ( CD VARCHAR2(8), NAME VARCHAR2(30), SDATE DATE, DATATEXT VARCHAR2(100) ) [unique constraint] CREATE UNIQUE INDEX TBL1_KEY1 ON TBL1 (CD, SDATE) PCTFREE 10 INITRANS 2 MAXTRANS 255 TABLESPACE INDEX_SPACE STORAGE(INITIAL 500K NEXT 500K MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT) LOGGING