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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 -
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 -
Using SQL; Server partition table function improves database read/write performance
Generally speaking, the first bottleneck point in a system is likely to be the database. For example, our production system has a high concurrency...
Database Operation Tutorial 2023-05-12 12:12:34 -
Row_ Summary of the usage of the number() function
Row_ The number() function is a type of SQLSERVER system function that assigns a continuous integer to each row in the partition of the result set. Simply put, it is to generate a unique table with the sequence number starting from the first row of each partition...
Database Operation Tutorial 2023-05-12 12:12:05 -
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 -
Practical cases of SQL Server database connection queries and sub queries
cataloguepreface1. Query the student ID, name, elective course ID, and grades of all students2...
Database Operation Tutorial 2023-05-12 12:11:09 -
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 -
SQL Server Single Table Data Query Example Explanation
catalogue1 Import data into SQL Server2 Example questions1. Query all information of all students2...
Database Operation Tutorial 2023-05-12 12:11:01 -
The issue of SQL database connection timeout expired
catalogueSQL database connection timeout has expiredproblemresolventSummary of database access timeout configuration1. Background2...
Database Operation Tutorial 2023-05-12 12:10:55 -
Tesla Raises Prices of Some Models in the United States
On May 12th, according to Tesla's official website in the United States, Tesla raised the prices of some models in the United States, with the Model Y being priced at $47490, the Model Y Long Range version being priced at $50490, and the Model Y High Performance version being priced at $54490. The selling price of the ModelS has been increased to $88490, and the selling price of the ModelSPlaid version has been increased to $108490...
Intelligent devices 2023-05-12 11:12:22
