The query would in fact execute without any error messages since the correlated subquery in SET clause returns EXACTLY one row for each row in B and the where clause executes without error. Lets say you have a table A ( id int, a1 varchar2(25) ) and a table B ( id int PRIMARY KEY, b1 varchar2(25) ). REGISTRATION(BIN, NAME, NAME_ALIAS, COR_GROUP, AUTHOBY, AUTHODATE, CG_NAME, ADD1, ADD2, ADD3, TEL1, FAX1, ADD5, ADD6, ADD7, TEL2, FAX2, ADD9, ADD10, ADD11, TEL3, FAX3, TP_TYPE, TRD_LINC, TRD_FY, TRD_AUTH, IMP_REG, EXP_REG, REG_TYPE, TIN, STATUS, PRE_BIN, DATREG, STAT_CHNG, ACT_CODE, ACT_MULT, ITEM_TYPE, OLD_ACT, APP_CAT, LCODE, ISSUE_DATE, VREG, M_POSI, MFUNC, SFUNC, LAST_USER, LAST_ACCS, TREG, PAY_FREQ, CREG, EREG, OREG, OP_BAL, OP_BAL_DT) select BIN, NAME---- from VIS. Thank u very much for ur kind & very helpful reply. Here the source tables have data with leading spaces and the target data should be without spaces.
If there is any variation, re-download the file until the sizes match.
 Update all plugins, uninstall any plugins you no longer need or disable all plugins, to see if that resolves the problem.
See Issues related to plugins for plugin locations and additional troubleshooting information, including how to disable plugins if your browser will not start.
You will not be able to start the browser until you first end all browser processes or restart the computer.
(If this is a recurring problem, read this for other possible solutions.)   Try starting Firefox or Sea Monkey in Safe Mode (see the linked article for details).