group by name

/***********************************************Duplicate records in two meanings:1. is a completely duplicate record, that is, all fields are duplicates of the record,2. is a duplicate record of some key fields, such as username field

Thanks to Sun Yunan's summary, address http://www.cnblogs.com/sunxiaonan/archive/2009/11/24/1609439.htmlFor example:ID Name Value1 a pp2 a PP3 B III4 B pp5 B pp6 C pp7 C pp8 C IIIID is primary keyAsk for such a resultID Name Value1 a pp3 B III4 B pp6

For example:ID Name Value1 a pp2 a PP3 B III4 B pp5 B pp6 C pp7 C pp8 C IIIID is primary keyAsk for such a resultID Name Value1 a pp3 B III4 B pp6 C pp8 C IIIMethod 1Delete yourtablewhere [id] not in (Select MAX ([id]) from yourtableGroup BY (name +

There are two ways to use it:1. Single Statement method:1) Delete b from Sys_test B, (select *,max (UUID) from Sys_test Group BY ' name ' have count (' name ') > 1) as D where B.uu Id>d.uuid and b.name = D.nameDelete b from Sys_test B is a set alias,

ifNot OBJECT_ID ('Tempdb: #T') is NULLdrop table #TGoCreate table #T ([ID]int, [Name] nvarchar (1), [Memo] nvarchar (2) ) Insert #TSelect 1N'A'N'A1'Union AllSelect 2N'A'N'A2'Union AllSelect 3N'A'N'A3'Union AllSelect 4N'B'N'B1'Union AllSelect

MySQL grouping and aggregation functionsThere are 5 Mysql aggregation functions:1, COUNT () number of records (count (1), COUNT (*) Table rows, count (column name) statistics column non-null number)2, max () maximum value3, min () minimum value4,

Oracle self-contained function wm_concat sorting when wm_concat connects strings, sometimes it is not sorted according to your requirements. For example, a table test has a field id, name, product Oracle self-contained function wm_concat sorting

For example:Id name value1 a pp2 a pp3 B iii4 B pp5 B pp6 c pp7 c pp8 c iiiId is the primary keyThis result is required.Id name value1 a pp3 B iii4 B pp6 c pp8 c iiiMethod 1Delete YourTableWhere [id] not in (Select max ([id]) from YourTableGroup by (

How does mysql Delete duplicate record statements ?? For example, idnamevalue1app2app3biii4bpp5bpp6cpp7cpp8ciiiid is the primary key required to obtain this result idnamevalue1app3biii4bpp6cpp8ciii method 1 deleteYourTable How does mysql Delete

Introduction: this is not a deep technical question, but a cool programming capability. This is not directly related to a person's development capabilities, but knowing this will be of great help to your SQL writing, troubleshooting and optimization.

1. Use the select statement to query the select * from data table name of a data table. 2. query the select Field 1 and 2from data table of one or more fields in the table; 3. query the specified data in the table. select * from the data table name

(1) Table Name: shopping information Number of commodity names of the shopper A A 2 B 4 C 1 A Ding 2 B C 5 ...... ( Others You can insert user lab records on your own) Records of buyers of two or more purchased items Answer: Select * from

For example:Id name value1 a pp2 a pp3 B iii4 B pp5 B pp6 c pp7 c pp8 c iiiId is the primary keyThis result is required.Id name value1 a pp3 B iii4 B pp6 c pp8 c iii Method 1Copy codeThe Code is as follows:Delete YourTableWhere [id] not in (Select

For example:Id name value1 a pp2 a pp3 B iii4 B pp5 B pp6 c pp7 c pp8 c iiiId is the primary keyThis result is required.Id name value1 a pp3 B iii4 B pp6 c pp8 c iiiMethod 1Delete YourTableWhere [id] not in (Select max ([id]) from YourTableGroup by (

Original post address: http://www.cnblogs.com/phpliu/archive/2010/06/21/1761726.html For example:ID name value1 A PP2 A PP3 B III4 B PP5 B PP6 c pp7 c pp8 C IIIID is the primary keyThis result is required.ID name value1 A PP3 B III4 B PP6 c pp8 C

For example:ID name value1 A PP2 A PP3 B III4 B PP5 B PP6 c pp7 c pp8 C IIIID is the primary keyThis result is required.ID name value1 A PP3 B III4 B PP6 c pp8 C III Method 1Delete yourtableWhere [ID] Not in (Select max ([ID]) from yourtableGroup by

(1) Table Name: shopping informationNumber of commodity names of the shopperA A 2B 4C 1A Ding 2B C 5......(You can insert records of other user experiments) Records of buyers of two or more purchased items Answer: Select * from shopping information

Convert multiple columns into one row, and convert multiple columns into one row. A friend asked me how to convert multiple columns into one row in Impala. In fact, the built-in functions in Impala can be implemented without using custom

-- Row and column conversion of classic SQL statements -- Http://www.programbbs.com/doc/4885.htm/##:normal row-column conversion (Version 2.0) Description: normal row-column conversion (version 1.0) only provides static and dynamic writing for SQL

– The structure of the table ' test '–CREATE TABLE IF not EXISTS ' test ' (' id ' int (one) not NULL auto_increment,' Name ' varchar (+) is not NULL,' Phone ' int (one) is not NULL,PRIMARY KEY (' id ')) Engine=myisam DEFAULT Charset=utf8;–– Export