Database Engineer exams (2)-Basic Oracle operations

 
// If the current user is root, use the sysdba role to connect to the Oracle instance.

# Su Oracle
# Sqlplus/nolog
# Conn/As sysdba

 

// Basic operation after connection

SQL> select username from dba_users; // view all user names
SQL> select table_name from user_tables; // view all tables of the current user
SQL> select table_name from all_tables; // View tables of all users
SQL> select table_name from dba_tables; // includes the system table
SQL> select table_name from dba_tables where owner = 'username'; // view the table of a user
SQL> DESC schema name. Table Name; // View table results
SQL> Select column name from Schema name. Table Name; // select a column in the table

 

 

2010.9.6 added:

 

Connect to the remote database: sqlplus username/password @ serverip/orcl

Here, username -- database username, password -- User Password, serverip -- IP address of the elasticsearch database server, orcl -- Oracle service name

 

Oracle converts all English letters in the input command into uppercase letters, such as the table name and field name. To Use lowercase letters, you must add.

 

For example, select "name" from "tblusers ";