Database Administrator

1. Table: table1 (FId, Fclass, Fscore). The most efficient and simple SQL statement is used to list the highest scores of each class. Two fields are displayed: class and score. Select fclass, max (fscore) from table1 group by fclass, fid 2. There is

Monty Widenius, the father of MySQL, announced the establishment of an Open Database Alliance with the goal of becoming the industry center of Open source Database MySQL. Monty Widenius said it would join all MySQL-related development and services

To install the Oracle database on Linux x86, perform the following steps: 1. install Linux and Oracle components; 2. Verify system requirements, Create users and groups, Create a directory, Configure Linux kernel parameters, Set Shell restrictions

Log_archive_dest_n allows you to set the archive location, which can be a remote location or a local location. You can configure 10 locations. For example, you can set it to point to the backup node server, it helps to ensure the security of

Because the data structure design of some modules in the Oracle project is not strictly in accordance with certain specifications, the data structure can only be queried from the database. The information to be queried is as follows: field name,

1. Execute the stored procedure in the Oracle database Proc. sh script content (in ibm aix environment) ORACLE_BASE =/oracle; export ORACLE_BASE ORACLE_HOME = $ ORACLE_BASE/product/10.2.0; export ORACLE_HOME ORACLE_SID = commdb; export ORACLE_SID $

I. Principle of master-slave Configuration: MySQL Replication is an asynchronous Replication process, from one Mysql instace (we call it the Master) to another Mysql instance (we call it the Slave ). The entire replication process between the Master

EXP-00091 error when exporting database dmp file in Linux Solution:1. view the NLS_CHARACTERSET value of the DB:SQL> select * from nls_database_parameters t where t. parameter = 'nls _ CHARACTERSET '; PARAMETER--------------------------------------

The slow_query_log_file log becomes very large and it is inconvenient to analyze its input items. We want to generate a slow_query_log_file file every day and analyze the log file every day. How to cut by day? We have come up with such a way to

Just installed Oracle 11gR2 RAC cluster Three nodes After creating a database, everything is normal. Then I installed an oracle client, and the ORA-12545 appeared during the link. Then the baidu is simple. Some people say it is the 11gR1 bug. Modify

-- Create the data table space t_space1 as the data table space name datafile as the data file path Create tablespace t_space1 datafile 'e: \ OracleTableSpace \ space_1 \ t_space1.dbf' size 5 M autoextend on next 5 M maxsize 20 M extent management

1. Introduction "Neo4j is a high-performance, non-relational, fully transactional, and robust graph database ." When processing complex network data, neo4j has excellent performance [1] and is suitable for social networks, dynamic networks, and

MySQL is a powerful open-source database. With more and more database-driven applications, people have been pushing MySQL to its limit. Here are 101 tips for adjusting and optimizing MySQL installation. Some tips are applicable to specific

Weibo will discuss how MySQL can reduce MySQL hang time When deleting a large table engine = innodb (30G + ). When buffer_pool is large (30 GB +), because the table is deleted, the entire buffer pool will be traversed to clean up data, resulting in

The semicolon is the end character of the SQL statement. This is also true in hql, but hive does not recognize the semicolon intelligently as follows: Select concat (';', 'A') from lhc limit 1; FAILED: Parse Error: line cannot recognize input near

Define a subquery• Describes the types of problems that subqueries can solve • lists the types of subqueries • Write single-row and multi-row subqueries • subqueries: types, syntaxes, and guidelines • single-row subqueries: -Group function in

The virtual environment has a RedHat 5.4 + 10 GRAC. You want to clear and deploy the 11.2.0.4 library to test goldengat 12c.When DBCA is used, node 2 reports Exception in thread "main"Xhl @ XHL :~ $ Ssh-X Oracle@192.168.3.201Oracle@192.168.3.201's

Note: by adding four listening services to RAC, different service names can be used to connect to different instances.1. View and use srvctl to add a service name [Oracle @ bysrac1 ~] $ Crs_stat-t-Bash: crs_stat: command not found[Oracle @ bysrac1 ~]

When update is used, there is only one subnode in most cases. Only when a subquery is used in the set clause can it have more than two nodes. If it has only one node, similar to the filter operation (exploring the filter principle in the execution

Backup tools are limited to xtrabackup (2.0 +) Umask is no stranger. It sets the default permissions for files (directories). Generally, the permissions for newly created directories are 755 and those for files are 644; However, MySQL has 700