group by name

Recent business Feedback A query exception problem requires the DBA to interpret the query result exceptions and help them resolve the problem. The problem essence is the problem of sorting the maximum within a group, and I built the test case

title: There is a test table containing three fields id,name,sex. Q: How do I query for duplicate data? Select Name,sex,count (*) from test GROUP by Name,sex has the count (*) >1.Q: How do I delete duplicate data and keep the data with the largest

MySQL GROUP by statementThe GROUP BY statement groups The result set based on one or more columns.On the grouped columns we can use COUNT, SUM, AVG, and so on.GROUP by syntaxSELECT column_name,function(column_name)operator Valuegroup by column_name;

First, create a sample tableCREATE TABLE testtable (name VARCHAR (ten), skill varchar), insert into TestTable VALUES (' Zhang San ', ' php '); INSERT INTO Testtab Le values (' Zhang San ', ' Java '), insert into testtable values (' Zhang San ', ' C #

There is a very interesting application with ROLLUP in MySQL's extended SQL, which is based on the statistical data of the group and then the same statistic (Sum,avg,count ... ), very similar to the functionality of statistical functions in Oracle,

From: http://blog.csdn.net/chinmo/article/details/21840201, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to determineSELECT * from Peoplewhere Peopleid in (select Peopleid from People GROUP by

Original is not easy, reproduced please be sure to indicate, original address, thank you for your cooperation!http://qindongliang.iteye.com/Pig series of learning documents, hope to be useful to everyone, thanks for the attention of the scattered

Preface DECODE () function, which compares the input value with the parameter list in the function and returns a corresponding value based on the input value. The parameter list of a function is a sequence of several numbers and their corresponding

The table has three columns: stunamem and subjectscore. table data includes: zhang San Language 0 Li Si Language 4 Wang Er English 90 Zhang San mathematics 333 requirements query results below student language English mathematics Zhang San 00333 Li

SQL deletes duplicate dataThis article provides a mysql statement for deleting duplicate data, that is, there are more than two duplicate data records in the data table, and the information with the smallest number is deleted.Delete 'borough _ name'

MySQL query repeated records in the table (1) 1. Search for redundant duplicate records in the Table. Repeat records determine the select * from peoplewhere peopleId in (select peopleId from people group by peopleId having count (peopleId)> 1) 2.

1. Copy the table structure and data, but do not copy the index and foreign key:Create table a select * from B;2. Copy the table structure, index, and foreign key without copying data:Create table a like B;3. Copy data only:Insert into a select *

SQL subquery instance SQL subquery instance introduction: A subquery is a query within a query. The results of the subquery are used by the DBMS to determine the results of the advanced query that contains the subquery. In the simplest form of a

This article summarizes how to delete the relational data between multiple data tables and multiple data tables at the same time. For more information, see. This article summarizes how to delete the relational data between multiple data tables and

The lifetime of a SparkSQL job Spark is a very popular computing framework developed by UC Berkeley AMP Lab, and Databricks created by the original team are responsible for commercialization. SparkSQL is an SQL solution built on Spark, focusing on

This article provides a detailed analysis of the implementation of Oracle SQL statements for querying and deleting jobs, for more information about how to query and delete duplicate records, see SQL statement 1. For more information about duplicate

SQL cross tabulation instance It's a simple thing. Many people on the internet asked "How to implement cross tabulation ?", The following is an example I wrote. The database is based on SQL Server 2000. -- ========================================

Sqlserver Delete duplicate records 1. Search for redundant duplicate records in the Table. duplicate records are determined based on a single field (peopleid ).Select* From peopleWhere peopleid in

Some time ago, I participated in the company's interview. One of the interview questions was the exchange of rows and columns in SQL. I know this idea, but I don't know how to implement it using SQL statements. Find and try it on the Internet.

A netizen in the group threw out the following question yesterday: Name Chinese Mathematical EnglishZhang San 75 90 85Li Si 80 85 85Obtain the table and query the subjects with the highest name score.Name score subjectJames 90 mathematicsLi Si 85