Tag:Duplicate record

  • MySQL notes, continuously updated

    Time:2021-10-7

    1. Because I’m making a statistical requirement that does not duplicate records recently, I naturally thought of distinct and count. So I found that the two guys can be used together. No duplicate records queried Select count (distinct column name) from table name; 2. Based on the above, statistics under different conditions will be extended. […]

  • Example of deleting duplicate records in data table in SQL Server

    Time:2021-7-17

    [PROJECT] Users table in database, containing u_ name,u_ PWD, where u_ Name has duplicate items. Now we need to delete the duplicate items! [analysis] 1. Generate a temporary table new_ Users, the table structure is the same as users table;2. Do a loop to the users table according to ID, read out a record from […]

  • Mysql database, how to deal with duplicate data?

    Time:2021-1-27

    preface In fact, there are two ways to solve the problem of whether duplicate data can be inserted, just like water control, the first is from the source, and the second is on the way of water flow. We continue to look down with these two ideas: problem In our MySQL database, there are often […]

  • Three methods of deleting duplicate records in Oracle query

    Time:2020-11-14

    For example, there is a personnel table (Table Name: peosons)If you want to record the name, ID number and address of the three fields exactly the same, Copy codeThe code is as follows: select p1.*   from persons  p1,persons  p2   where p1.id<>p2.id   and  p1.cardid = p2.cardid and p1.pname = p2.pname and p1.address = p2.address The above […]

  • [Oracle] – set operation: Union, union all

    Time:2020-10-13

    Three types of set operations are provided in Oracle: Union, intersect and minus Union: Union,Duplicate records are displayed only once。 Union all: Union all, display all record information. Intersect: find intersection Minus: returns the difference set of two query results ​ Let’s introduce the set operation of Oracle 1、 Data preparation Create emp10 table based […]

  • Methods of querying and deleting duplicate records in MySQL

    Time:2020-7-30

      preface This paper mainly introduces the methods of querying and deleting duplicate records in mysql, and shares them for your reference. Here’s a detailed introduction: Find all records with duplicate Titles: 1 select title,count(*) as count from user_table group by title having count>1; 1 SELECT * FROM t_info a WHERE ((SELECT COUNT(*) FROM t_info WHERE Title = a.Title) > 1) ORDER BY Title DESC 1、 Find duplicate records 1. […]

  • [SQL interview question 1] MySQL or Oracle Database

    Time:2020-7-6

    There are three interview questions as follows: Create two tables: CREATE TABLE CUSTOMERS ( ID NUMBER(2), NAME VARCHAR2(10) ); CREATE TABLE ORDERS ( ID NUMBER(2), CUSTOMERID NUMBER(2) ); SELECT * FROM CUSTOMERS; INSERT INTO CUSTOMERS VALUES(1,’JOE’); INSERT INTO CUSTOMERS VALUES(2,’HENRY’); INSERT INTO CUSTOMERS VALUES(3,’SAM’); INSERT INTO CUSTOMERS VALUES(4,’MAX’); SELECT * FROM ORDERS; INSERT INTO ORDERS […]

  • Loading feature master data to automatically delete duplicate key values

    Time:2020-2-17

    When extracting the attribute data of information object, an error is found. After checking, it is found that the data source has duplicate key values Originally, I wanted to delete duplicates in the start routine and found that DTP already has this function. Check [process duplicate key value] in DTP [update] After re execution, duplicate […]

  • SQL deletes duplicate records in tables

    Time:2019-10-13

    When we encounter the problem of duplicate records in the table, it is the fastest to delete SQL directly, so we should not copy it slowly to find it manually in the excel table. Following sql, find the duplicate record and the record with the lowest ID value in the duplicate record (the ID in […]

  • Method Sharing of Deleting Duplicate Records in SQL Server 2008

    Time:2019-9-12

    Now let’s see how to delete these records in SQL SERVER 2008. First, we can simulate some simple duplicate records: Copy codeThe code is as follows: Create Table dbo.Employee ( [Id] int Primary KEY , [Name] varchar(50), [Age] int, [Sex] bit default 1 ) Insert Into Employee ([Id] , [Name] , [Age] , [Sex] ) […]