SQL>show;
Valid options are:
CHECKs                   COMMENTs                 COLLATEs
COLLATIONs               DOMAINs                  DB
DATABASE                 DEPENdency               DEPENdencies
EXCEPtions               FILTERs                  FUNCtions
GENerators               GRANTs                   INDexes
INDICES                  MAPping                  PROCedures
PACKages                 ROLEs                    SYStem
SEQuences                SECURITY CLAsses         SECCLAsses
SCHEmas                  TABLEs                   TRIGgers
USERS                    VIEWs
Command error: show
SQL> show SCHEmas;
Command error: show SCHEmas