Database Administrator

Why NoSQL? Relational databases have become part of the computer culture due to their many advantages: Obtain persistent data Data can be persisted to the disk, and it is easy to access a small piece of data. Concurrency Relational databases have

Enable MySQL to support Emoji expressions Let MySQL support Emoji expressions. We recommend that you use the utf8mb4 character set in advance for MySQL databases involving wireless connections. What is the difference between utf8mb4 and utf8? In the

Oracle string truncation and splicing applications Today, someone asked me a question about Oracle string truncation and concatenation. I asked him to write an SQL statement. After reading the Problem description, I tried to solve it clearly, using

Oracle Parameter Optimization 1. Upgrade to 11gR2The Oracle Database Upgrade Assistant (DBUA) Configuration tool includes a Command Option to automatically expand system files, which can be upgraded from oracle express (XE or free version) to its

Analysis of several cases where the MySQL index will fail During the project process, it is inevitable that an index is created for MySQL, but the query is still very slow, next we will analyze the causes and solutions for this situation. Indexes

Install MySQL5.6 In the RPM package of CentOS6.5 1. View information about the operating system. [Root @ bkjia ~] # Cat/etc/issueCentOS release 6.5 (Final)Kernel \ r on an \ m[Root @ bkjia ~] # Uname-Linux bkjia 2.6.32-431. el6.x86 _ 64 #1 SMP Fri

How to Use Logdump and how to use logdump How to Use Logdump           Written on Thursday, April 16, 2015 Prepared by: snail mail QQ: 295013648     Use the following command in GGSCI to view the currently processed queue file and RBA number, for

Common query methods in oracle and common methods in oracleCommon query methods in oracleQuery all user information in oracleSelect * from dba_users;Query only users and passwordsSelect username, password from dba_users;Query current user

MySQL modifies the copy user and password, and mysql modifies the user In the production environment, you sometimes need to modify the password of the copied user account, for example, the password is lost, or because multiple different copied users

Install MySQL In Debian and DebianMySQLTo install MySQL In Debian, follow these steps: Debian:/# apt-get install mysql-server After installation, the root account has no password by default and can be changed. Debian:/# mysqladmin-u root password

Import a text file to the mysql database table and insert command to insert data to the table, mysqlinsert 1. Import a text file to a database TABLE: mysql> load data local infile 'text path 'into TABLE name; example: mysql> load data local

Data Mining basics: Find the relevant project-level algorithm in the data, and mine data-level data. Ck: Candidate itemset of size kLk: frequent itemset of size kL1 = {frequent items}; for (k = 1; Lk! =; K ++) do begin Ck + 1 = candidates generated

Note: (1) MySql usage This article is intended for those who previously engaged in enterprise-level application development, because enterprise-level applications, especially financial enterprises, usually use Oracle or DB2 as databases. Compared

Create and test the full-text index of SqlServer. -- Create test TABLE -- drop table FullTextIndexingCREATE TABLE FullTextIndexing (id int identity (1, 1) not null, Sentence VARCHAR (MAX )) -- create a CLUSTERED index alter table FullTextIndexing

SQL Server can concurrently obtain the maximum document number in the subscription database to test and solve the bill !, SQL Server Act Note: Many transaction systems require document numbers, and it is a headache to obtain document numbers

Difference between left join, right join, and inner join in SQL, joininnerDifference between left join, right join, and inner join in SQL Left join returns records that include all records in the left table and join fields in the right table.Right

Run scripts to transfer dynamic SQL statements and Report SQL statements. In most cases, the SQL statements of the report data source are fixed, but sometimes some of them need to be dynamically spelled out, for example, in a report application, you

Database Tuning tutorial (2) Prepare slow query data and optimize Databases 1. Slow query found In the previous section, we talked about the definition of slow queries. This section describes how to create a large table and prepare data for slow

Database Tuning tutorial (9) index TuningIii. Index 6. Several Common possibilities of indexing but not being used I talked about when to avoid using indexes, but sometimes I don't know how to use indexes. Below are several cases where indexes

Quickly build a slave Database Based on mysqldump and 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