Database Administrator

Create table test(Id int unsigned not null PrimaRY KEY AUTO_INCREMENT,Username VARCHAR (15) NOT NULL)AUTO_INCREMENT = 100; In database applications, we often use unique numbers to identify records. In MySQL, The AUTO_INCREMENT attribute of the data

After switching to Oracle11g today, when UTL_TCP was used to interact with the Service Program, an ACL Access Control Problem was reported. Fortunately, there were still some network basics, what is ACL, In the Oracle11g environment, to enhance the

The bare device created in AIX is the logical volume in AIX. The creation method is as follows: Syntax: mklv-t raw-y [lvname] [vgname] [LPs] For example, when creating a bare device required by Oracle: Mklv-t raw-y lv_sysaux datavg 3 Mklv-t raw-y lv_

When you use ROLLUP or CUBE for GROUP operations, fields with NULL values are generated, then, how can we tell whether the field itself is NULL or generated by ROLLUP and CUBE? In this case, GROUPING (groupingfield) can be used to solve the problem.

SQLiteIs a lightweight database that compliesACIDAssociationRelational Database Service (RDS) is already used in many embedded products. It occupies very low resources and may only require several hundredKThe memory is enough. It

ROLLUP literally means to roll to, used in group by can play a cumulative sum role: If no ROLLUP exists, the following query sums the groups by department_id and job_id: SELECT department_id, job_id, SUM (salary) FROM employees WHERE

The principle is just a concept, and the operability is not strong. I read N-plus semi-Principles and semi-Details related articles, but I am always confused by various details. In order to quickly use PostgreSQLProcedure for configuring a

According to my recent study on Oracle databases, I have learned more about Oracle and hope to help some new Oracle users. Oracle provides several simple data types, Unlike SQL server. Common Oracle data types include char, varchar2, clob, number,

Most of the time, the operating system is Windows, and Liunx is rarely understood.During this time, an image system requires that all applications be deployed on the RedHat system. In this way, there are two software usage problems: 1. Database 2.

1.Queries the current tablespace of a database. Select tablespace_name, file_name, sum (bytes)/1024/1024 table_size from dba_data_files group by tablespace_name, file_name;   2.Create a tablespace Create tablespace data01 DATAFILE

The use of the Oracle learning notes package can make the functions and stored procedures clearer. At the same time, you must add the package name when calling these functions and stored procedures... /** Create and use a package Syntax:

Linux: RedHat Enterprise Linux 5.6 Oracle version: 10 GB 1. Modify the/etc/oratab File Set orcl:/home/oracle/product/10.2.0/db_1: N Changed to orcl:/home/oracle/product/10.2.0/db_1: Y. 2. Modify the $ ORACLE_HOME/bin/dbstart file under the oracle

Oracle control statement Logical control statements in Oracle If elsifElse EndIf SetServeroutOn; DeclarePer_dep_count number; Begin Select Count(*)IntoPer_dep_countFromEmp; If per_dep_count> 0Then

Last week, a colleague encountered an error while installing Oracle in Linux. The installation was not successful. The supervisor asked me to re-install it. Only after all the previous installations are deleted can we ensure the installation is

1. Start the NAS + SERVER (fully started) Check whether the NFS service starts the service nfs status. 2. Start RAC1 and RAC2 (it is best to start RAC1 separately and start RAC2 after it is fully started) Check whether the mount is correct

First, log on as an Oracle user 1. $/oracle/app/product/101/bin/dbstart: Start the database. 2. $/oracle/app/product/101/bin/dbshut: Shut down the database. 3. $/oracle/app/product/101/bin/dbca: Database Configuration assistant for database

Symptoms: the Database is open or can be connected to the Database from sqlplus. When you connect to the Database from the web, you can find the Database Instance, Listener, agent Connect to Instance is normal, but clicking 'database' cannot enter

1. Install Oracle database software1) Check basic requirements (mem: 1024 M, swap: mem *. Can be skipped)Memory sizeGrep MemTotal/proc/meminfoSwap partition sizeGrep SwapTotal/proc/meminfoAdd swap PartitionCreate a partition file such as/home/swap.

PostgreSQL lists SQL statements in progress SELECT Procpid, Start, Now ()-start AS lap, Current_query FROM (SELECT Backendid, Pg_stat_get_backend_pid (S. backendid) AS procpid, Pg_stat_get_backend_activity_start (S. backendid) AS start,

View Oracle Database Table lock example-Fault Locating 1. Start a session session1 (actually, you can establish a connection with the database through a third-party software or directly use sqlplus) SQL> select sid from v $ mystat where rownum =