Database Administrator

Usage of order 1. Processing of null in order Default processing: Oracle considers null as the maximum value in order by, so if it is asc, it is placed at the end, and desc is placed at the top. We can use nulls first or nulls last to control the

Quickly build a slave Database Based on mysqldump Mysql master-slave architecture is generally divided into three steps: one is to add the parameters required for replication to the master instance and the other is to create a snapshot in the master

Semi-synchronous replication instance of MySQL5.6 one master and multiple slaves Semi-sync introduction:By default, MySQL replication is asynchronous, which means that the master server and its slave server are independent. Asynchronous replication

How to modify the character encoding of mysql 5.6.24 decompressed (Installation-free or zip), mysql 5.6.24   [It takes nearly three hours to solve the default encoding problem of this character. The modification method provided on the Internet is

What is the difference between the set and select assignment modes in SQL ?, Sqlselect The variables in the T-SQL are divided into local variables and global variables, the use of local variables is first declared, and then assigned a value. Global

SQL Server recursive query and SQL Server recursive query -- SQL Server recursive query, mainly used to create a tree structure IF OBJECT_ID ('category') IS NOT NULL DROP TABLE CategoriesGOCREATE TABLE Categories (CategoryID INT, CategoryName

Oracle Data Pump (expdp) backup reports ORA-39006: internal error, expdpora-39006 in Linux Problem description: Oracle has been using a Data Pump backup, today at the terminal backup suddenly reported ORA-39006: internal error. The data pump

Database indexing technology, database indexingTechnical Principle index is a structure that sorts the values of one or more columns in a database table (for example, the name column of the employee table. If you want to search for him or her by the

Mysql for Mac and mysql for Mac 1. Install mysql 2. Start the mysql service in preference settings 3. Open the terminal and enter mysql. chenhong:~ chenhong$ mysql-bash: mysql: command not found 4. Set the mysql command and enter 1) alias mysql =

Automatic PostgreSQL backup tutorial in Windows and postgresql backup tutorial BackgroundAn automated system is required for my work on a PostgreSQL database project to perform backups every day. After some research, we decided to create a Windows

Note the following when using the date type in PostgreSQL: postgresql date Those of us who use Rails will not be surprised when they see 5. weeks. from_nowor3.days.ago + 2. hours. Similarly, PostgreSQL can also achieve the same functionality by

Describes the jsonb data type in PostgreSQL, postgresqljsonb PostgreSQL 9.4 is loading a new feature called jsonb, which is a new type of data that can store JSON data that supports GIN indexes. In other words, the most important feature in the

MySQL obtains the continuous range. mysql obtains the range. 1. Raw Data 2. Convert running_number into data and add an ordered number to the column. SELECT d. running_number + 0 running_number, @ a: = @ a + 1 rn FROM device_data d, (SELECT @ a:

[Hibernate] Hibernate cluster query, grouping query, sorting and time difference, hibernate Cluster In Hibernate, HQL statements can basically implement what SQL statements do, just as jQuery does javascript. Although the HQL statement is a query of

Mysql recursive query tree table and mysql recursive tree table Drop table if exists 't_ areainfo '; create table 't_ areainfo' ('id' int (11) not null AUTO_INCREMENT, 'level' int (11) DEFAULT 0, 'name' varchar (255), 'parentid' int (11), 'status'

If an archive log is deleted, the offline datafile cannot be accessed. An archive log is deleted and the offline datafile cannot be accessed. In fact, it is more appropriate to change the title to "rebuid online index encounters the problem of

DS stack achieves digital conversion (Supplement) and ds achieves digital conversion In computer hexadecimal conversion, binary, octal, decimal, hexadecimal, and conversion between them are commonly used. In real life, the most commonly used decimal

Installation notes for centos 6.5 mongodb3.11, centosmongodb3.11 Http://www.mongodb.org/downloads Download Curl-O-L https://fastdl.mongodb.org/linux/mongodb-linux-i686-3.0.2.tgz Unzip and install Tar-xvzf mongodb-Liunix-xxxxx.tgz Start

(14) mysql events and 14mysql events Overview The event scheduler is a new feature after MySQL5.1. It can trigger an operation on a database according to a custom time cycle and can be understood as a time trigger,Similar to crontab in linux, or

Process for creating an oracle database: Process for creating an oracle database Since there is already a database instance in the current environment, this does not affect the creation of a new instance sun Current System instance [Oracle @ DBA2