Category:DBT

  • Introduction to MySQL Source command

    Time:2021-10-27

    Reflections on an online problem At work today, my development colleagues took a. Zip compressed package file and said that they wanted to pour the data into the database. Originally, they thought it was formed SQL. They just need to copy and paste it and pour it into the database. When I got it, I […]

  • SQL Server 2012 cannot connect to the WMI provider solution

    Time:2021-10-27

    Today, a colleague encountered the following error when starting the SQL Server 2012 configuration manager of his working machine: Unable to connect to WMI provider. You do not have permission or the server cannot be accessed. Note that you can only use SQL Server Configuration Manager to manage SQL Server 2005 servers. The specified module […]

  • MySQL FAQs

    Time:2021-10-26

    reset password Close MySQL servicesudo /etc/init.d/mysql stopRun in MySQL safe mode and skip permission verificationsudo mysqld_safe –user=mysql –skip-grant-tables –skip-networking &Log in to MySQL as root with an empty passwordsudo mysql -u root mysqlUpdate passwordupdate user set Password = PASSWORD(‘root’) where User =’root’;update mysql.user set authentication_string=password(‘root’) where user=’root’ ;Refresh permissionsFLUSH PRIVILEGES;sign outquitThe password is too simple. […]

  • Mongodb introduction and Development Guide

    Time:2021-10-26

    catalogue1、 Introduction to mongodb2、 Build mongodb3、 Java with mongodb4、 Spring session mongodb5、 Mongodb development specifications and examples6、 Mongodb + nodejs See Annex: mongodb introduction and Development Guide for details_ 20200409224211.pdf Mongodb learning exchange group:

  • Addition, deletion, modification and query of MySQL common command manual

    Time:2021-10-26

    1、 Database operation Create database Syntax: CREATE DATABASE database_name; Delete database Be careful when deleting the database! Because after executing the delete command, all data will disappear. Syntax: DROP DATABASE database_name; Select database Syntax: USE database_name; 2、 Data table operation data type value type type size purpose TINYINT 1 byte Small integer value SMALLINT 2 […]

  • Optimized implementation of count() for MySQL large tables

    Time:2021-10-26

    The following is my judgment based on the combination of the data structure of the B + tree and the speculation of the experimental results. If there is any error, please correct it! Today, I experimented with the count () operation optimization of MySQL. The following discussion is based on mysql5.7 InnoDB storage engine. X86 […]

  • Summary of SQL server link server technology

    Time:2021-10-26

    1、 Link MySQL using Microsoft OLE DB provider for ODBC Install the ODBC driver for MySQL 1. Create an ODBC system data source for MySQL. For example, select the database as test and the data source name as myDSN 2. Establish linked database EXEC sp_addlinkedserver @server = ‘MySQLTest’, @srvproduct=’MySQL’, @provider = ‘MSDASQL’, @datasrc = ‘myDSN’ […]

  • [Mr. Zhao Qiang] use mongodb’s Web console

    Time:2021-10-25

    Mongodb can monitor the database through the web interface. By default, this option is turned off and needs to be turned on at startup.Enableweb Console, need to be startedmongodbAdd:–httpinterface Start mongodb and observe the output log information:   Use the browser to access port 28017 to see mongodb’s Web console interface.  

  • MySQL restores data through binlog

    Time:2021-10-25

    objective By understanding the relevant configuration of binlog log, you can simply master the data recovery operation of database through binlog; MySQL log file Any mature software will have a mature log system. When there is a problem with the software, these logs are the treasure house to query the source of the problem. Similarly, […]

  • Introduction to database transactions

    Time:2021-10-25

    1、 Transaction classification Transaction is a program execution unit that accesses and updates various data items in the database. Transaction will convert the database from one consistent state to another consistent state. This is the purpose of transaction and one of the important characteristics that distinguish the transaction model from the file system. Transactions in […]

  • Implementation method of adding field annotation to MySQL create table

    Time:2021-10-25

    Direct Po codes and cases #Write comments when creating tables CREATE TABLE userinfo( Id int comment ‘number’, Uname varchar (40) comment ‘user name’, Address varchar (120) comment ‘home address’, Hobby varchar (200) comment ‘hobby’ )Comment = ‘user information table’; #Modify comments for tables Alter table userinfo comment ‘user information table’; #Modify the comments of the […]

  • Sample code for creating and deleting constraints using SQL statements

    Time:2021-10-25

    Create and delete constraints using SQL statements Constraint type Primary key constraint: the primary key column data is required to be unique and cannot be empty. Unique constraint: the column is required to be unique and can be null, but only one null value can appear. Check constraint: limit the value range and format of […]