Database Administrator

Related order statistics for mysql and related order statistics for mysql 1. the requirements are as follows: Recipient shipping address Order Number user ID Zhang San, Beijing 1001 1 Zhang Si Shanghai 1002 2 Zhang Wu, Beijing 1003 3 ZHANG Liu,

Oracle Installation check if the DISPLAY variable is set error, oraclevariable Original Works are from the blog of "Deep Blue blog". You are welcome to reprint them. Please note the following source when reprinting them. Otherwise, you will be held

Oracle practical tips and oracle tips 1. Flashback Note: delete the "T_SPC_ROOM" table, but you can use the following command to restore the table without commit. flashback table MW_APP.T_SPC_ROOM to before drop2. Handling special characters NOTE:

Introduction to E-R model, E-R analysis and e-r Model Analysis 1 Overview 1.1 Role of the ER Model Taking the example of a building house, the role of architects, construction engineers, and raw material suppliers is illustrated, and the roles of

LeetCode Second Highest Salary, leetcodehighest Write a SQL query to get the second highest salary fromEmployeeTable. + ---- + -------- + | Id | Salary | + ---- + -------- + | 1 | 100 | 2 | 200 | 3 | 300 | + ---- + -------- + For example, given

[Translated from mos] Create synonym and mossynonym for table partition Reference: How to Create a Synonym on a Table Partition (Doc ID 119805.1)   How to Create a Synonym on a Table Partition:=============================================You cannot

Postgresql auto-increment statement and Postgresql increment statement If it is simply starting from 1 and the incremental value is 1, you can write it like this. serail is a special type: Add Value and result to Employee: If you want to set

(8) view in mysql, view in mysql Concept   ViewIt is a virtual table, which is basically the same as a normal table for users who use views. The view does not exist in the database, and the data in the view is dynamically generated.Advantages of the

Log on to the mysql database at the command prompt. Format: mysql-h server address-P server port number-u username-p C: \ Users \ Administrator> mysql-h localhost-P 3390-uroot-p (the-P before the port number is a capital letter) Enter password: *

Dump leaf block of Oracle indexes, oracleleaf Dump the Oracle index leaf block F: \ oracle \ product \ 10.2.0 \ db_1 \ BIN> sqlplus/as sysdbaSQL * Plus: Release 10.2.0.4.0-Production on Thu Apr 9 06:28:17 2015 Copyright (c) 1982,200 7, Oracle. all

LeetCode Rising Temperature, leetcode GivenWeatherTable, write a SQL query to find all dates 'IDs with higher temperature compared to its previous (yesterday's) dates. + --------- + ------------ + ---------------- + | Id (INT) | Date (DATE) |

LeetCode Customers Who Never Order, leetcodecustomers Suppose that a website contains two tables,MERsTable andOrdersTable. Write a SQL query to find all customers who never order anything. Table:MERs. + ---- + ------- + | Id | Name | + ---- + --

Database optimization tutorial (7) cost and cost of INDEX OPTIMIZATIONIii. Index 4. index costThe previous sections introduced the power of indexes in improving performance and how to use indexes. However, indexes also have overhead. 1) disk space

Mongodb monogstat and mongodbmonogstat Environment Introduction:Monogdb 2.4.10Command Introduction: view the performance status of the active monogdb instance Main parameters:Execute unzip stat -- helpIn addition to command usage, a keyword field

Database optimization tutorial (8) under what circumstances should indexes be used and indexes be optimized?Iii. Index 5. Under what circumstances should indexes be used? Since the index has a cost, you should not use it without using the

Database optimization tutorial (13) Other MySQL database Optimization MethodsVi. Other MySQL database Optimization Methods In the last chapter, we will talk about some optimization methods not mentioned above. 1. My. ini configuration file Here

Database optimization tutorial (12) Optimize SQL statements and optimize SQL statements5. Optimize SQL statements The previous chapter describes how to design a good table. A good table naturally requires a good SQL statement to operate on it. This

Sakila data usage learning records and sakila data recordsImport sakila Database Download the sakila database and see the sakila-data. SQL data file and sakila-schema file. Create database sakila on the database; Use sakila and use the

Database Tuning tutorial summary, Database Tuning Summary Some time ago, I helped the company optimize the database. With my previous knowledge, I used the learning knowledge step by step in practice, and finally I got the speed up, it takes only

Oracle converts the score row into a column, and oracle scores 1. The table contains the following data: Name Subject January February March Zhang San Chinese 30 40 50 Zhang San