Database Administrator

Two auto-increment methods for Oracle Database primary key (SEQUENCE and trigger)1. Preparations Create an Oracle database table. In the user table SYS_USERS, user_id is the primary key. -- Create tablecreate table SYS_USERS( user_id NUMBER(9)

Oracle initialization or shutdown in progress solution appears after the data file is deleted by mistake in oracleI. Error Analysis 1. In this case, the tablespace generated after the following SQL statement is executed. -- Custom tablespace data

Use XtraBackup for MySQL master-slave replication without locking tables Xtrabackup is an open-source project of percona to implement the innodb Hot Backup function similar to InnoDB's official Hot Backup tool. It can quickly back up and restore

Expdp and impdp parameter usage 1. Create a logical directory. This command does not create a real directory in the operating system. It is best to create a directory as an administrator such as system.Create directory dpdata as '/opt ';2. Check the

Restoration test after Oracle 11gR2 database files are lost I. Test EnvironmentThe database version is Oracle 11gR2. After completing a full backup, shut down and create a snapshot. After each boot, the database executes the alter system switch

What is the 'virtual columns 'of MySQL 5.7? MySQL 5.7 introduces a very practical function: Virtual column Generated (Virtual) Columns. For its purpose, we use a scenario to describe it. Suppose there is a table containing a column of the date type.

Oracle Releases high water level line /*************************************** **************************Cause: because the original exported database did not sort the table space, there are two main aspects. First, the user generated too many

ORA-12170: TNS: Connection timeout problem solved The virtual machine can access the database normally, but the physical machine connection to the database appeared "ORA-12170: TNS: Connection timeout", you can solve the problem with the following

Oracle Database File Management Database files include data files, log files, control files, password files, and parameter files. Management of these files can be seen as the process of adding, deleting, modifying, and querying. 1. Data File

Install MongoDB on CentOS7 MongoDB is one of the most well-developed NOSQL databases. It is eye-catching in the storage of big data and space data!Generally, mongoDB is deployed on a linux System in enterprise-level applications. For Tom, deploying

Master-slave database settings for Yii2 As the project grows, the master and slave databases are still indispensable. Using the Yii framework for development, how do I set the master and slave databases? It is actually very simple. First, modify the

MySQL database migration MySQL database migration (direct migration of data files) In late October this year, the company's servers needed to be migrated, which involved MySQL database migration. Check the MySQL data file size, which is close to 60

Oracle uses RMAN for data migration Overall process: perform A hot backup for the database of machine A, and perform A full backup. Then, use the scp command to upload the backup to machine B, stop database A (note that archive is not triggered when

SparkSQL reads data in Hive Because Spark uses CDH of Cloudera and is automatically installed and deployed online. I recently learned SparkSQL and saw SparkSQL on HIVE. The following describes how to read HIVE data through SparkSQL. (Note: if you do

Notes for installing the lnmp environment by bogo Video tutorial address: https://chuanke.baidu.com/v5659343-234411-1698133.htmlCreate a virtual machine Note: After the configuration is complete, click Finish (the reason is that the selected

Common PHP Redis operations, phpredis connect ('2017. 0.0.1 ', 6379);/** string */$ redis-> set ('name', 'huangyuxin'); echo $ redis-> get ('name '); $ redis-> setex ('name', 10, 'setex '); // set the lifecycle $ redis-> del ('name '); // delete/**

Comparison between MySQL and Oracle five stored procedures & functions, mysqloracle Stored Procedure & Function No. Category ORACLE MYSQL Note 1 The statement for creating a stored procedure is different.

Unable to connect to server 127.0.0.1: 27017: Unable to connect because the target machine is actively rejected. 127.0.0.1: 27017. type: MongoDB. driver. mongoConnectionExceptionStack: at MongoDB. driver. internal. directConnector. connect (TimeSpan

Table B: 3 million, primary key IDDelete records with ID = Table A IDs from Table B.Delete from B WHERE EXISTS (SELECT 1 FROM (SELECT ID FROM (SELECT T. ID, rownum rn from a) where rn> 0 and rn However, the execution plan shows that the COST is

REVER-----54321 SQL> select reverse ('oracle ') from dual;REVERS------ElcarO SQL> select reverse ('test') from dual;REVE----???? NAME TYPE VALUE-----------------------------------------------------------------------------Nls_language string