U
UNDEFINE command, 155, 157
underscore character (_), 40
undoing changes. See ROLLBACK
Unicode, converting to and from, 472
UNION ALL operator, 184 “185, 535 “536
UNION operator, 185 “187, 535 “536
unique constraint violated (error), 253
UNIQUE constraints, adding, 303
Unix
environment variables for Java, 477 “478
forward slash character (/) for directories, 10, 433
LD_LIBRARY_PATH environment variable, 480
UPDATE statements, 21 “22, 374, 376, 379 “380, 431 “432
containing subqueries, 178
DEFAULT keyword in, 256
modifying rows using, 250 “252
SET clause in, 251
updating cells , 243 “244
UPPER() function, 62, 67, 317
user_col_comments table, 308
user_col_privs_made view, 279 “280
user_col_privs_recd view, 281 “282
user_cons_columns view, 306
user_constraints view, 305, 326
user -defined constructors, 385 “387
user-defined types, 368, 555
user_ind_columns view, 318 “319
user_indexes view, 318 “319
user_nested_tables view, 397
user_procedures view, 350 “351
user_role_privs view, 286 “287
users, 272 “274
creating, 272 “273
deleting, 274
user's password, changing, 273 “274
user_sequences view, 311 “312
user_sys_privs view, 275 “276
user_tab_columns view, 297
user_tab_comments view, 308
user_tab_privs_made view, 278
user_tab_privs_recd view, 280
user_triggers view, 362 “363
user_varrays view columns , 392 “393
USING clause
with inner joins, 57
for joins, 56 “57
in MERGE statement, 257
UTC (Coordinated Universal Time), 120