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Summary of several methods for removing duplicate data in SQL (window function for data deduplication)
catalogueMethod 1: distinctMethod 2: groupbyMethod 3: Window functionWhen using SQL to extract and analyze data, we often encounter scenarios where data is duplicated, requiring us to perform data deduplication and subsequent analysis.Taking the sales report of a certain e-commerce company as an example, we commonly use distinct or group by statements to deduplicate data...
Database Operation Tutorial 2023-05-12 12:13:26 -
Complete uninstallation and reinstallation of SQL Server
catalogueComplete uninstallation and reinstallation of SQL Server1. Control Panel Delete Names with&quo; SQL” Procedure for2...
Database Operation Tutorial 2023-05-12 12:13:17 -
Sql Server Management Implementation steps for Studio to connect to MySQL
targetGiven MySQL connection parameters (address and user), expect to use Microsoft; SqlServer Management Studio (hereinafter referred to as MSSSMS) connects to MySQL and directly queries or modifies data in MySQL in MSSSMS.realizationStep 1/4: Download and install MySqlConnector/ODBC at MySQL:: DownloadConnector/ODBCSelect the corresponding installation file based on the number of bits in the operating system...
Database Operation Tutorial 2023-05-12 12:13:01 -
SQLServer Index Fragmentation Query and Processing of Tables
1.2...
Database Operation Tutorial 2023-05-12 12:12:48 -
sql server The issue of not being able to fully utilize the number of logical cores in the CPU in 2016
Recently, I encountered a problem in my work where sqlserver2016 cannot fully utilize the CPU core. Through analysis tools, I can see that;There are a total of 72 CPU cores, but SQL Only 40 cores can be used, and many people have encountered this problem...
Database Operation Tutorial 2023-05-12 12:12:37 -
SQL Server Detailed steps for changing the default backup directory for databases
This article also applies to the latest version of SQL server 2008, 2016, 2019Open SSMSSelect Database, right-click, PropertiesSelect&quo; Permissions”, Click on&quo; View Server Permissions&# quo;Select&quo; Database Settings;, Modify&quo; Backup; Box PathNote: After changing the backup path of a database, it is valid for all databases. Please note that the final prompt indicates whether to save...
Database Operation Tutorial 2023-05-12 12:12:17 -
SQL Server judges whether there is summary for database, table, column, view, stored procedure and function
catalogue1 Introduction Overview2 Database related judgments2.1...
Database Operation Tutorial 2023-05-12 12:11:57 -
SELECT... Specific usage of INTO
catalogue1 SELECT… INTO Introduction2 SELECTINTOFROM statement3 The difference between select in from and insert in to select:From the official manual address of MySQL 5.71 SELECT… INTO IntroductionSELECT… INTO is used to store query results in variables or write them to files...
Database Operation Tutorial 2023-05-12 12:11:37 -
Detailed explanation of SQL Server's memory management architecture
WindowsSQL Server 2.12...
Database Operation Tutorial 2023-05-12 12:11:27 -
SQL Detailed explanation of server's row level security
catalogue1 Preface2 Description3 Permissions4 Security note: Side channel attack5 Cross functional compatibility6 Example1 PrefaceRow level security allows you to control access to rows in database tables using group membership or execution context.Row level security (RLS) simplifies security design and coding in applications...
Database Operation Tutorial 2023-05-12 12:11:21 -
SQL Server's execution plan
catalogue1 Background2 Display and Save Execution Plan3 Display estimated execution plan4 Display actual execution plan5 Save execution plan in XML format6 Compare and analyze execution plans6.1 Comparison of execution plans6...
Database Operation Tutorial 2023-05-12 12:11:18 -
SQL Detailed explanation of sub queries for Server
catalogue1 Basic knowledge of sub queries2 Sub query rules3 Column names in qualified subqueries4 Multi layer nesting of subqueries5 Related sub queries6 Sub query typesummary1 Basic knowledge of sub queriesA subquery is a query nested within a SELECT, Insert, UPDATE, DELETE statement, or another subquery.You can use subqueries anywhere an expression is allowed...
Database Operation Tutorial 2023-05-12 12:11:06
