Initial knowledge of Oracle

Unable to log on at logon: No listener ——— start Service Oraclexetnlistener Listener does not currently recognize the request service in the connection description ———— Restart service oracleservicexe check Tnsnames.ora ho St Value

When PL/SQL is not installed: Run sqlplus login, user_tables table View all users Oracle: to; end of a sentence

Oracle data type: Character data type: Char,varchar2,nchar, nvarchar2 numeric data type: Number datetime data type: Date,timestamp LOB data type: Blob,clob,bfile * * Varchar,integer,float,double and other types are not recommended

Pseudo-column: rowID: Identifies data in a database rownum: commonly used for writing pagination

--Paged Query
--(pageNo-1) *pagesize= start line pageno*pagesize= end Line

SELECT * FROM (
Select RowNum rm,s.* from (
SELECT * from MYFIRSTTB ORDER BY stuage Desc) s where rownum<=5) where rm>=1;

Experience: Committing a transaction to commit or rollback after adding a delete modification statement in Oracle: Commit/rollback

Initial knowledge of Oracle