Database Administrator

Destructive Testing of dual tables With regard to dual table destructive testing, since it is a destructive test, it needs to be determined that this test is limited to testing or personal learning, and some SQL statements may seem extremely simple,

Use trigger to call shell in MysSQL & MariaDB In Windows: Drop function if exists lib_mysqludf_sys_info;Drop function if exists sys_get;Drop function if exists sys_set;Drop function if exists sys_exec;Drop function if exists sys_eval; Create

The ORA-01940 cannot delete the user that is currently connected   When importing data in the test environment today, you need to remember the drop user operation. When you execute the drop user, the prompt is: ORA-01940: cannot drop a user that is

Install and use the MySQL Performance Testing Tool sysbench We need to use AWS and Azure MySQL services at work. We need to test and compare the performance of the two cloud services. As a result, Baidu + google began to search for performance

PostgreSQL export data dictionary documentation You need to sort out the data dictionary documents of the current database on the project. The project is not standardized. Such documents should be supplemented later. Each field in these tables is

Oracle redo complexity-oracle Core Technology Reading Note 3, redo-oracle I. Overview We know that in oracle, Every modification to a piece of data generates a redo (that is, redo, which records the modified content ). The purpose is to back up the

Redis for beginners (2) -- using Redis as the Mysql database cache, redismysql Two problems must be solved when Redis is used as the Mysql database cache. First, determine the data structure used to store data from Mysql. After determining the data

MySQL loads the JDBC driver and mysql loads the jdbc driver. First, install the MySQL database. MySQL5.5 is installed. The installation steps are not described here. Please note that if the installation process stops at the start service and

SQL Application and Development: (9) Improving efficiency indexes and SQL Indexes In a database, an index is a special object. It is a database structure that can accelerate data retrieval. It can quickly find the desired content from a large amount

Mysql HA-Install Keepalived + LVS + Mysql (dual master) On Redhat 6.3, keepalivedlvs Host information: Scheduling node: Name: lvsOS: Redhat 6.3IP: rule: 192.168.56.236 data node 1: Name: rule: Redhat 6.3IP: 192.168.56.230 data node 2: Name:

After mysql is uninstalled, the mysql service is still in progress and the read description fails. Error Code 2 and mysql error code First, I used 360 software manager to uninstall mysql5.5. After I uninstalled mysql, I deleted the mysql

Oracle special character escape: & and ', oracle special character escapeWhen we run the SQL show all command in SQL * PLUS, we can find a parameter: define & (hex 26), as shown below:Concat. (hex 2e)Copycommit 0Copytypecheck ONDefine & (hex

Characters corresponding to the ASCII code value and ascii characters Chr (9) tab space chr (10) newline chr (13) carriage return Chr (13) & chr (10) carriage return newline chr (32) space character chr (34) double quotation marks chr (39) single

Internet connection to intranet mssql and intranet connection to intranet mssql Reference: http://www.nat123.com/Pages_8_266.jsp The method in this article is as follows: (1) install and enable nat123 on the Intranet, add ing, and use other

It takes only 6 minutes to scan a 166G table from an oracle full table, and oracle166g How can I maximize the cpu usage? How to quickly scan a large table. If a large table has a primary key, count (*) takes the primary key. oracle only needs to

I SELECT a table in a production test database when a ORA-01578, a block damage, previously learned how to deal with block damage, to really have not met, today finally let me met, it's still a production test database, so you don't have to be

By slimming the database through the file system, it is to serialize the big data in the database and the data not involved in the search to a certain location on the hard disk through the file stream. The storage location uses the hash path, that

In the design of database applications, we often need to obtain the total number of records in some tables to determine whether the total number of records in the table is too large and whether data needs to be backed up. Our common practice is:

What is Database Links? First, we will explain its role: to allow users to access another remote database through one database. The Database Link stores the connection information of the remote Database. As shown in: Scott can query the emp table

In the process of using the Sybase database, we often encounter locks in the Sybase Database System. In most cases, users must log on to the system as Super Users to process the process. To ensure the security of the Sybase Database System, the