group by name

Mysql distinct usage-when using mysql to filter out non-duplicate data, you sometimes need to query records with no repeated fields, although mysql provides the keyword distinct to filter out redundant duplicate records and retain only one record,

How can I improve the efficiency of sorting this simple mysql? [Select distinct A. name from table A order by (select sum (num) as num from table where name = A. name) desc In a table, the name field is repeated, and the num field is a number ..

When using mysql, you sometimes need to query records with unique fields. Although mysql provides the keyword distinct to filter out redundant duplicate records, only one record is retained, but it is often used to return the number of records that

Tzh's written test mainly involves T-SQL. Original questions: ID Value 1 1 2 1 5 2 6 2 8 3 9 3         Difficulty: Calculate grouping statistics sorted by ID

There are several identical records in thousands of records. How can I use SQL statements to delete duplicates?1. Search for redundant duplicate records in the Table. duplicate records are determined based on a single field (peopleid ).Select * from

The distinct keyword can be used to remove duplicate rows from the results of the SELECT statement. If noDistinct: All rows, including duplicate rows, are returned. For example, if you select all author IDs in titleauthorDistinct, the following rows

Comparison and usage of distinct and group by statements in MySQL, mysqldistinct The data table records the bibliography used for user verification. Now I want to retrieve all the bibliography and use DISTINCT and group by to get the expected

Recently, due to the surge in archive logs, deleting archivelog all seems to be unable to clear all archived logs. Why? 1. Demo Environment SQL> select * from v $ version where rownum BANNER ---------------------------------------------------------

Zookeeper Problem Description In the evaluation system, the row-to-column application of data is involved in the query of instructor scores. First, the following problems to be solved are described: The Data Structure Stored in our database is

Summary of Row-to-column conversion problems-1. Row-to-column conversion (various problems in the forum will be sorted out later) --- 1. Simplest row-to-column Conversion/* Question: Suppose there is a student orders table (TB) as follows:Name

Summary of Row-to-column conversion problems-1. Row-to-column conversion (various problems in the forum will be sorted out later) --- 1. Simplest row-to-column Conversion/* Question: Suppose there is a student orders table (TB) as follows:Name

$ Link = mysql_connect ("localhost", "root", "root ");$ Db = mysql_select_db ("bustest", $ link );$ Sql1 = "Select name from Info group by name order by id asc ";Print (" ");$ RES1 = mysql_query ($ sql1 );While ($ row1 = mysql_fetch_array ($ RES1 )){

SQL server interview questions, SQL SERVER interview questions I went to the interview today and got caught by a small database problem. I am ashamed and brave. SQL interview questions 1. I can't help but want to say this, because the field

When using mysql, you sometimes need to query records with unique fields. Although mysql provides the keyword distinct to filter out redundant duplicate records, only one record is retained, but it is often used to return the number of records that

How to convert the Column records of database records into rows under sqlserver. For more information, see. How to convert the Column records of database records into rows under sqlserver. For more information, see. Assume that there is a student

Mysql deletes the record statement bitsCN.com in the subquery. Mysql deletes record statements in a subquery. SQL code delete from t_5star where locationid in (select e. locationid from (select a. * from t_5star as a, t_als_data as B where a.

Duplicate records in the MySQL Query table: bitsCN.com Query repeated records in the MySQL table (1) 1. search for redundant duplicate records in the table. Repeat Records determine the select * from peoplewhere peopleId in (select peopleId from

1. Show multi-column to single lineData file and content: Student.txtxiaoming|english|92.0xiaoming|chinese|98.0xiaoming|math|89.5huahua|chinese|80.0huahua|math|89.5To create a table studnet:CREATE table Student (name String,subject string,score

PHP generates the table instance code. The following code is used to generate a table instance in PHP, which is post after the program home test runs normally on this site .? Php $ linkmysql_connect (localhost, root, 123456); $ dbmysql_select_db.

Usage of distinct in SQL bitsCN.com When using mysql, you sometimes need to query records with unique fields. Although mysql provides the keyword distinct to filter out redundant duplicate records, only one record is retained, but it is often used