Oracle

   1 SELECT DISTINCT USERNAME FROM DBA_USERS;

   1 SELECT * FROM ALL_IND_COLUMNS WHERE TABLE_NAME='XYZ';
   2 SELECT * FROM ALL_TAB_COLUMNS WHERE TABLE_NAME='AAA';

   1 SELECT index_name, table_owner, table_name, uniqueness FROM USER_INDEXES WHERE table_name = 'XYZ';
   2 SELECT index_name, table_owner, table_name, uniqueness FROM ALL_INDEXES WHERE table_name = 'XYZ';

   1 SELECT * FROM all_source WHERE name = 'myprocedure'
   2 ORDER BY owner,name,line

   1 SELECT distinct owner,table_name 
   2 FROM all_tables
   3 ORDER BY owner,table_name;

   1 select table_name,partition_name,num_rows
   2 from user_tab_partitions
   3 where table_name='TEST';

   1 CREATE SEQUENCE sample_seq  START WITH 1 INCREMENT BY 1;
   2 CREATE SEQUENCE sample_seq2 MINVALUE 1 START WITH 1 INCREMENT BY 1;
   3 SELECT * FROM ALL_SEQUENCES; -- show all sequences
   4 

   1 -- table creation
   2 CREATE TABLE Employee 
   3 ( idEmployee number(12), name varchar2(255), lastName varchar2(255),
   4 constraint pkIdEmployee PRIMARY KEY(idEmployee)
   5 );
   6 -- sequence creation
   7 CREATE SEQUENCE seqEmplyee 
   8 start with 1 increment by 1 minvalue 1 maxvalue 65536;
   9 -- insert values
  10 INSERT INTO Employee (idEmployee,name,lastName) 
  11 values(seqEmplyee.nextval,'Bart','Simpson'); 
  12 INSERT INTO Employee (idEmployee,name,lastName) 
  13 values(seqEmplyee.nextval,'Peter','Griffin'); 
  14 INSERT INTO Employee (idEmployee,name,lastName) 
  15 values(seqEmplyee.nextval,'Homer','Simpson'); 
  16 -- check sequence current value
  17 SELECT seqEmplyee.currval FROM dual;

   1 -- login with system user
   2 create tablespace christs datafile 'c:\christs.dbf' size 100m;
   3 create user chris identified by 12345678 default tablespace christs;
   4 alter user chris quota unlimited on christs;
   5 grant create session to chris;
   6 grant create table to chris;
   7 
   8 -- login with user chris
   9 create table CHRIS.test ( name varchar(255) ) tablespace chris;
  10 insert into CHRIS.test (name) values('Test name 1234');
  11 
  12 -- login with system user
  13 -- user alice to just run selects
  14 create user alice identified by 12345678 default tablespace christs;
  15 grant create session to alice;
  16 grant select on CHRIS.test to alice;
  17 
  18 -- login with alice
  19 select * from CHRIS.test;