Database Administrator

/** The core solution is to generate a column from 1 to 10 as the "secondary column "**/Select level l FROM dual connect by level [Problem]Two tables A BTable:Id pidA1 1A2 2A3 3Table B:Pid pnumber1 22 33 5Generate such information based on the

Statement for Oracle row-to-column conversion: /* Drop table foo; */ /** Create a demo table **/ Create table foo ( Bbbid number (2), -- primary key Depid number (2), -- unit NUMBER AAC006 VARCHAR2 (1) -- Gender 1 male 2 female 0 unknown CONSTRAINT

1If you can perform remote operations, set the ssh service on the serverA. Modify the sshd_config file and run the command vi/etc/ssh/sshd_config.B. Remove the # PasswordAuthentication no comment and change NO to YES.C. Remove the # PermitRootLogin

To partition the Collection objects stored in the MongoDB database, you need to select the Shard Key. The selection of the Shard key directly determines whether the data distribution in the cluster is balanced and whether the cluster performance is

OracleThere are two types of database parameter files:Pfile (Initialize the parameter file)And the other isSpfile (Server initialization parameter file); ActuallySpfileYesPfileA new parameter file derived from the Application9iFor later

Restore with rman, current redo log corruption1. Full database backupRMAN> run {Allocate channel c1 type disk maxpiecesize = 500 m;Backup current controlfile format '+ dgasm/backup/haozg/ctl _ % d _ % s ';Backup full database format' +

1. Full database backup Note: rman can back up the data files on asm to the file system or restore them. RMAN> run {Allocate channel c1 type disk maxpiecesize = 500 m;Backup current controlfile format '+ dgasm/backup/ctl _ % d _ % s ';Backup full

Create persons:Create table 'persons '('Id _ P' int (11) not null AUTO_INCREMENT,'Lastname' varchar (10) default null,'Firstname' varchar (10) default null,'Address' varchar (50) default null,'City' varchar (10) default null,Primary key ('Id _ p '));

After RAC is started, crs_stat-t displays two resources in the unknown status, as shown below: Oracle @ RAC1 [/home/oracle] crs_stat-tName Type Target State Host------------------------------------------------------------Ora... SM1.asm application

1. view the space occupied by each table of the current user: Select Segment_Name, Sum (bytes)/1024/1024 From User_Extents Group By Segment_Name; 2. view the space occupied by each tablespace: Select Tablespace_Name, Sum (bytes)/1024/1024 From

You can export a data table from the local Oracle database with the file name. dmp, and then import the dmp file to the oracle table of another host. Deep feelings. I am not familiar with the functions of oracle files. First, modify the content of

1. query timeSQL> select to_char (sysdate, 'yyyy-mm-dd hh24: mi: ss') from dual; TO_CHAR (SYSDATE, 'yy-------------------2012-07-22 14:27:13 2. delete user SCOTT and objectsSQL> drop user scott cascade; 3. Set the system time format$ Export NLS_DATE_

MySQL master-slave synchronization is a mature architecture: advantages:① The query can be performed on the slave server (that is, the READ function we often call) to reduce the pressure on the master server.② Back up data from the master server to

I upgraded MySQL from 5.1.26-rc to 5.5.15. The source code packages downloaded from the official website are compiled. MySQL 5.5.15 is provided by my colleagues.Because the existing database uses the innodb engine, mysqldump is used to export the

Under what circumstances does Oracle select generate redo? 1 ') Fast block clearing or commit cleanout. When a transaction is committed, oracle marks the flag in the itl entry of the data block as U 2) sets the commit scn In the Scn/Fsc column.

Because the Performance Tuning section of the official Book does not index by configuration item, quick query cannot be achieved. So I re-organized the original text with the configuration item drive and added some of my own understandings. If there

Variable binding is widely used in OLTP environments. This is due to OLTP features and SQL statement execution processes. Typical OLTP transactions are short. Similar SQL statements have high execution rate and high concurrency; oracle performs hash

Only Oracle is installed in Linux, and an Oracle user is installed in Linux. The user's directory is in/home/oracle Therefore, you must use an Oracle user before logging on to Oracle. Su-oracle conversion user Sqlplus/nolog does not connect to

Description:Blue=Command name Light Green=Command Parameters Light blue=Option Purple=Directory System Environment:CentOS 1, 5.7 X86_64 1. installation overview User name:MysqlInstallation Directory:/Usr/local/mysql-5.5.20Database

The SessionFactory of Hibernate can hold an optional level-2 cache, which can improve the persistence access performance of Hibernate. Hibernate has the following attributes about level-2 Cache. Hibernate. cache. provider_class: This attribute is