Oracle

Recently, derivative work is required to import data from several tables to one table, where data may be duplicated. Therefore, data comparison is required before import. Method 1: I used group by having count (*)> 1 to extract the duplicate data

1. Date interval operation Current Time minus 7 minutes Select sysdate, sysdate-interval '7' minute from dual Current Time minus 7 hours Select sysdate-interval '7' hour from dual Current Time minus 7 days Select sysdate-interval '7' day

The new oracle11g database was used yesterday. It was a relatively simple problem. I should have done something about configuring TNS and modifying connectstring. Who knows? A user name and password error is reported as soon as the database is

1. Connecting via TNS "Data Source = NEWDB; User ID = SYSTEM; Password = admin "; 2. Connecting Without TNSNames. ora "Data Source =" +"(DESCRIPTION =" +"(ADDRESS_LIST =" +"(ADDRESS = (PROTOCOL = TCP)" +"(HOST = 127.0.0.1)" +"(PORT = 1521)" +")" +")"

1. Connection sequence in the WHERE clause: Oracle uses the bottom-up sequence to parse the WHERE clause. According to this principle, the join between tables must be written before other where conditions, and those conditions that can filter out

1. view the table space name and size. Select t. tablespace_name, round (sum (bytes/(1024*1024), 0) ts_size From dba_tablespaces t, dba_data_files d Where t. tablespace_name = d. tablespace_name Group by t. tablespace_name;　　 2. view the name and

Working overtime today, we found that all oracle services on the database server were lost-that is, there were no oracle services in the Service Manager, such as OracleOraDb10g_home1TNSListener and OracleServiceORCL.Solution:1. Export all oracle

Two days ago, when installing Oracle 10g, I encountered the problem of "Microsoft LoopBack Adapter configured as the system's primary network Adapter", and found other solutions on the Internet, the following is a summary: Stop the current "Local

　I. Oracle Data Dictionary A data dictionary is a place where Oracle stores database information. It is used to describe data. For example, the Creator information, creation time information, tablespace information, and user access permission

1. Connection: 1. equijoinDikar set connectionSelect ename, A. deptno as a_deptno, B. deptno as B _deptno, B. dname as departmentFrom emp a, DEPT BEquijoinSelect ename, A. deptno as a_deptno, B. deptno as B _deptno, B. dname as departmentFrom emp a,

Since there are not many contacts with Oracle and there are few training companies, such a company is just a scam. It is estimated that there is no great development!Let's get down to the truth.I have debugged a program that executes Oracle

0. database parameter attributesCol PROPERTY_NAME format a25Col PROPERTY_VALUE format a30Col DESCRIPTION format a100Select * from database_properties; Select * from v $ version; 1. Find the SID of the current session, SERIAL #SELECT Sid, Serial #

How to remotely determine Oracle DatabaseOf InstallPlatform Select * from v $ version; View table space usage Select sum (bytes)/(1024*1024) as free_space, tablespace_nameFrom dba_free_spaceGroup by tablespace_name; Select a. TABLESPACE_NAME, A.

Analysis Function over and Window Function  I. analysis function overOracle provides analysis functions starting from 8.1.6. analysis functions are used to calculate a group-based aggregate value. What is different from aggregation

A few months ago, I was confused and changed the machine name from "south" to "southyj ". It took a long time to discover that Oracle cannot be used. Check the cause. It turns out that when Oracle is installed, the directory will be generated based

In the new year, I summarized some of the books I have read before. Many of them are worth reading and reading, and many are also sleepy after several pages. Below are some books related to databases that I think are good at. I can't wait to share

--- 1. Normal equal connections Select E. last_name, D. department_name From employees e, departments d Where E. department_id = D. department_id; --- 2 left Outer JoinSelect E. last_name, E. department_id, D. department_nameFrom employees eLeft

Software environment: 1. Windows 2000 + ORACLE 8.1.72. ORACLE installation path: C: ORACLEImplementation Method: 1. Choose "start"> "Settings"> "Control Panel"> "Administrative Tools"> "services" to stop all Oracle services. 2. Start-> Program->

Create or replace trigger testTAFTER INSERT OR UPDATE OR DELETE ONFor each rowDeclare-- Local variables hereBeginIF INSERTING THENInsert into B (a, B) VALUES (: NEW. a,: NEW. B );ELSIF DELETING THENDelete from B WHERE a =: OLD.;ELSEUPDATE B SET B =:

Oracle net connections 1 local naming Connection Method: CONNECT username/password @ SERVICE_NAME (which is commonly used) Modify the tnsnames. ora file as follows: Sales =(DESCRIPTION =(ADDRESS = (PROTOCOL = tcp) (HOST = sales-server) (PORT = 15