The specified data is grouped and the number of repetitions is obtained in Oracle

One 、 Business needs

    The business needs to realize grouping for the specified fields , And get the repetition times of the content under each group after grouping ; Also get the duplicate personnel information content .

    such as ： I have a personnel information form here , I need to know about all age groups after , The age repeats those ？ Then get the personnel information of repeated content .

Two 、 Thought analysis

    Oracle in ① For grouping Group by  Having sentence ;② Although there is no direct access to repeated statements , But you can use Count After obtaining the number , We are making a comparison to make the number greater than 1 You can get the duplicate content ;③ Can be used for comparison IN Condition or exists Conditions .

 

3、 ... and 、 Implementation method

3.1、 Group the specified data and get the number of repetitions syntax

SELECT  You need to judge the duplicate field name ,COUNT( You need to judge the duplicate field name )repateNumber FROM  Table name  GROUP BY  You need to judge the duplicate field name  HAVING COUNT( You need to judge the duplicate field name )>1 

3.2、 Group the specified data and get the repeated content information syntax

SELECT * FROM  Table name  WHERE  Duplicate field name to be judged  IN (SELECT  Duplicate field name to be judged  FROM  Table name  GROUP BY  Duplicate field name to be judged  HAVING COUNT( Duplicate field name to be judged )>1 ) 

3.3、 Take the content of personnel information table as an example

3.3.0、 Contents of personnel information table

3.3.1、 Get what age is repeated in the personnel information table and how many times

SELECT "Age",COUNT("Age")repateNumber FROM "PeopleInfo" GROUP BY "Age" HAVING COUNT("Age")>1 

 3.3.2、 Get the personnel information with the same age in the personnel information table

SELECT * FROM "PeopleInfo" WHERE "Age" IN (SELECT "Age" FROM "PeopleInfo" GROUP BY "Age" HAVING COUNT("Age")>1 )