Oracle Learning Notes

Chapter One: Oracle database has a default of three users: Sys/system/scott (normal user)

Oracle database when creating a new user, because there is no permission to log on to the system, but also to assign it permissions (database permissions and System permissions), at least the Create Session system permissions Required

Oracle database Roles (role) are mainly: Connect role/Resource role/DBA role, and a regular user with connect and Resource two roles for regular database development work

Oracle's role includes a set of system permissions and normal object permissions that allow permissions to be delegated to the role, granting permissions or roles to the user. System permissions can only be authorized by DBA users, and object permissions are authorized by the user who owns the object

Before the client connects to the server, the server starts the listening service, and the client tool installs the Oracle client, and the client wants to establish a local network service name. Oracle services and monitoring are started before the database can be manipulated. Oracle's services are: 1, oracleservice+ service name (basic services, must be turned on for normal use of the database) 2, Oracleoradb10g_home1tnslistener is the server side of the client to provide monitoring services 3, Oracleoradb10g_home1isql*plus can be used for remote login and database operation after opening

Oracle must be started with sys user, command: Startup Open/Close command: Shutdown immediate

Chapter Two: In Oracle, strings are concatenated with double vertical bars (| | Said

Set operation: Is the grouping of two or more result sets into a single result set. The set operations include: 1, INTERSECT (intersection), returns the records that are common to two queries. 2, union All, returns all records for each query, including duplicate Records 3, UNION (unions), returns all records for each query, excluding duplicate records 4, minus (complement), returns the records retrieved by the first query minus records retrieved by the second query Note: When using a collection operation, the number of columns returned by the query and the type of the column must match, and the column name can be different

An outer join between two tables or several tables in Oracle is indicated by (+), which appears in the condition on the left, pointing to the right outer connection, and the left outer connection on the right. Example: E. DEPTNO (+) =d.deptno means right Join

Database built-in tables commonly used types are: numeric type number (p,s), variable string varchar2 (length), date

In Oracle, default is a value and there is no default constraint

Chapter III: