Oracle

First, using RowNum, no order by (optimal scheme)The following example queries out 5003 rows of data, then throws out the previous 5000 rows, returning 300 rows. After testing, this method is the lowest cost, nesting only one layer, the fastest!

The ORACLE SQL sort is sorted according to two criteria, according to the ID number from small to large sort, while the Country field is the first row in Beijing, followed by Shanghai,. Dalian, and finally other cities, how to write?The wording is

In the development of the report, it is unavoidable to encounter the problem of row to column.For example, in the case of Scott's EMP in Oracle, you can use "Row to column" to count the number of people in each position in each department:The

Automatically disconnects after a database is started (about 10 minutes)method One, directly modify the resource configuration fileThree steps to complete in a sqlplus environment.The first step is to query the resource file and find the profile

Role:1. Stored procedures are compiled only at creation time, and normal SQL runs once per execution, so using stored procedures can improve database execution speed. 2. When complex operations are performed on a database, such as when you update,

Package util;Import java.sql.Connection;Import Java.sql.DriverManager;Import java.sql.PreparedStatement;Import Java.sql.ResultSet;Import java.sql.SQLException;public class Dbconn {public static Connection getconnection () {Define a Connection

Backup and recovery are frequently encountered operations, logical backups, and physical backups. Physical backups are also divided into cold and hot backups.One, logical backup, recoveryRefers to the use of the exp command, simple, does not affect

Character typeChar fixed length, Max 2000 characterschar (10) ' xiaoming ', followed by 6 characters will be wasted, suitable for defining fixed-length and frequently queried fields, such as ID number, high efficiencyVARCHAR2 variable length, max 400

1, determine the database global variable name and instance nameDb_name = ORCLSID = ORCL2, Determine the database administrator authentication method;The administrator's authentication method includes the operating system authentication and the

Stored procedures for sending messagesCreate or replace procedure up_send_mail (SUBJECTINVARCHAR2), mail_content  in varchar2 (a), Re_out out number (2)) as/********************************* Write: Dead leaf effect: Send message Date: 2013-03-13

1. On the premise that the environment variable is well configured, strike the command #>sqlplus2. Enter username/password Login Oracle #> default we use first, user name: Scott, password: Tiger login3.A. When you log in, you can only tap Sqlplus,

SELECT * from V$nls_parameters;Sqlplus "/As SYSDBA"Sql> SHUTDOWN IMMEDIATESql> STARTUP MOUNTsql> ALTER SYSTEM ENABLE RESTRICTED SESSION;sql> ALTER SYSTEM SET job_queue_processes=0;sql> ALTER SYSTEM SET aq_tm_processes=0;sql> ALTER DATABASE OPEN;sql>

Starting with the 3rd block, the block stores all of Oracle's operational records. The block structure is simple, with only the size and block body:struct BK { redo_bh blockhead; uint8_t buf[496];} REDO_BK;REDO_BKThe size is the same as the

Example 1: Set up a trigger, when the Staff table EMP table is deleted a record, the deleted records are written to the Staff table delete log table. CREATE TABLEEmp_his as SELECT * fromEmpWHERE 1=2; CREATE OR REPLACE TRIGGERTr_del_emp beforeDELETE

Subquery: Contains another query inside a query.Normal subquery--Query for information about all employees that are higher than the 7654 wage select * from emp e where e.sal > (select Sal from emp where empno = 7654);--query out wages higher than 765

Plsql garbled how to deal with:Configure environment variables:Nls_lang simplified Chinese_china. ZHS16GBKStart plsql always Prompt "Ora-12154:tns: Unable to resolve specified connection identifier "1, configuration plsqlClick Preferences-connection-

Today just met the need to do this function, conveniently search the network, several methods are listed, convenient for later reference.1 What is the merging of multi-line strings (connection strings), for example:sql> desc test;Name Type Nullable

Turn: Use of merge into in Oracle, oraclemerge Recently, Oracle's Merge was used in the project. This command uses a statement to update and insert data to a table from one or more data sources. in ORACLE 9i, the UPDATE and INSERT keywords must be

View the powerful Concept from the introduction of NOTNULL integrity constraints Oracle Concept is the official book we learned on a daily basis. One reason is that there are many problems. In the final analysis, we can find some explanations and

Modify the oracle 10g Character Set and oracle10 g Character Set Modify the character set of oracle 10 GB Modify the database character set to ZHS16GBK.View server character sets SQL> select * from V $ NLS_PARAMETERS; Modify: $ sqlplus/nologSQL>