group by name

The magic of MySQL will support select * from the Employee group by name This counter-logical SQL (assuming that the table is not just a column of name)The logic of MySQL is: The return field of select, if not in GroupBy, is not a statistical

MySQL GROUP by name Group to get the most value one, do not understand Ah, ask for doubts. Select A.* from Test a where 1 > (select COUNT (*) from test where name = A.name and val > A.val) SQL statement, the field that displays the largest Val value

Select A.* from Test a where 1 > (select COUNT (*) from test where name = A.name and val > A.val) SQL statement, the field that displays the largest Val value by name group Issue: SELECT COUNT (*) from test where name = A.name and val > a.val

There are two Repeated Records. One is a completely repeated record, that is, records with all fields being repeated, and the other is records with duplicate key fields, such as duplicate name fields, other fields are not necessarily repeated or can

In the process of preparing a database interview, first on the Internet a sea search, to find the history of interview questions, and then a bone a bone after the gnawing, now basically these problems (or called practice) are no problem. The

Original: http://www.cnblogs.com/zhangzt/archive/2010/07/29/1787825.html MSDN Documentation: Https://msdn.microsoft.com/zh-cn/library/ms177410.aspx According to the original text, a slight change, code specifications. --First, row column--1,

-- Process duplicate table records (query and delete)/*************************************** **************************************** **************************************** *******************************1. Repeat records with the same num and

-- Process duplicate table records (query and delete) /*************************************** **************************************** **************************************** ******************************* 1. Repeat records with the same num and

Find duplicate data T-SQL in the database ========== first article ============ there are duplicate records under a field in a table, there are many ways, however, there is a method that is relatively efficient. The following statement: Select

--Processing table duplicate records (query and delete)/************************************************************************************************************** ****************************************1, Num, name of the same duplicate value

-- Group data by a certain field to get the data of the row with the maximum (small) ValueCopy codeThe Code is as follows:/*The data is as follows:Name val memoA 2 a2 (the second value of)A 1 a1 -- the first value ofA 3 a3: The third value ofB 1 b1 -

About with cube, with rollup and grouping View the help document of SQL 2005 to find the specific difference between CUBE and ROLLUP.: The result set generated by CUBE displays the aggregation of all the combinations of the values in the selected

Query and delete duplicate records of the SQL statement  1, find redundant records in the table, duplicate records are based on a single field (ID) to determine the  select * from table where Id in (select ID from table group Byid have COUNT (ID) > 1

The mysql group obtains the first few records (ranking) in each group and the groupby and orderby research bitsCN.com -- obtains the data of the row where the maximum (small) value is located by grouping by a certain field /* The data is as

Mysql database groups are divided into three methods. Temporary tables are used for group by, compact (Tight) index scanning, and group by and Loose index scanning, but I often use 1. Use Loose index scanning to implement GROUP What is loose index

About with cube, with rollup and grouping View the help document of SQL 2005 to find the specific difference between CUBE and ROLLUP.: The result set generated by CUBE displays the aggregation of all the combinations of the values in the selected

About with cube, with rollup and grouping View the help document of SQL 2005 to find the specific difference between cube and rollup.: The result set generated by cube displays the aggregation of all the combinations of the values in the selected

About the WITH cube, with rollup and grouping The specific differences between cube and ROLLUP are found by looking at the Help documentation for SQL 2005 : Cube produces a result set that shows aggregates for all combinations of values in the

0x00 PrefaceSQL injection constructs the statement through user input to achieve the purpose. A word, do not believe any user input content, do a good job of protection.0x01 method of transfer of parametersThe method of transmitting parameters is

MySQL query repeating fields, and how to delete duplicate recordsMySQL, database, Database, field, serverThere is a large table in the database and you need to look for a duplicate record ID for the name in order to compare it. If you are simply