remove duplicate rows in sql

about 4 hours. 4 hours, a long time. It takes less than 10 minutes to insert 5 million data deduplication (1/2 duplicates) to a temporary table.Remove duplicate records from SQL statements and obtain duplicate records Search for duplicate data with these fields in the table based on several field names and delete the

This is one of the problems that you encounter in your daily work.Dt_user_pay_record tableID UserID Time Money122014-3-2 2222015-3-2 33322011-9-5 5452016-2-2 66552015-4-4 77Remove dataUserID Time Money22015-3-2 3352016-2-2 66I want to take out the same UserID and time Max data.Scenario 1:SELECT * FROM (Select ID, user_id, created, Pay_money,Row_number () over (partition by user_id ORDER by created DESC) seq from dt_user_pay_record) tbl where seq =1Scenario 2:SELECT * FROM Dt_user_pay_record T1Wh

SQL SELECT DISTINCT Statement Grammar: SELECT DISTINCT column name from table name using DISTINCT keyword If you want to select all the values from the company column, we need to use the SELECT statement: SELECT Company from Orders To select only a different value from the company column, we need to use the Select DISTINCT statement: The code is as follows Copy Code SELECT DISTINCT Company from OrdersLet's take a look

Write a SQL query to delete all duplicate e-mail entries in a table named Person , keeping unique emails based on its smallest Id. +----+------------------+| Id | Email |+----+------------------+| 1 | [Email protected] | | 2 | [email protected] | | 3 | [Email protected] |+----+------------------+id is the primary key, column for this table.For example, after running your query, th

by Field 1, Field 2, Field 3 having COUNT (*) > 1) Where: Field 1, Field 2, Field 3 refers to the three fields that need to establish a unique constraint, selfid refers to one of the self-increment fields in tables table. 2. Delete duplicate records and keep only the Selfid minimum records, that is, the first inserted records:[SQL]View Plaincopy DELETE from dbo. Tablesign WHERE S

Someone in the group asked a question today. I have a table named test, which contains three fields A, B, and C. Now field B has a lot of duplicate data. Some of these duplicate data fields are empty, some have data, and the C field is correct. Excuse me: I want to remove duplicates Based on the B field. If the two data fields are the same, and the field is empty

Given a sequenced file, Uniq deletes the duplicate rows and outputs the results to standard output. Uniq is typically used in conjunction with sort to remove duplicate rows from the sort output.Command formatUniq [OPTION] ... [INPUT [OUTPUT]]Command parameters-C,--countOutpu

Linux text processing tools are very rich and powerful, such as a file: Copy Code code as follows: Cat Log Www.jb51.net 192.168.1.1 Www.jb51.net 192.168.1.1 Www.jb51.net 192.168.1.2 Ffffffffffffffffff Ffffffffffffffffff Eeeeeeeeeeeeeeeeeeee Fffffffffffffffffff Eeeeeeeeeeeeeeeeeeee Eeeeeeeeeeeeeeeeeeee Gggggggggggggggggggg You can remove duplicate

DataTable removes duplicate rows and performs distinct based on a field. datatabledistinct There are many methods on the Internet, such as using view processing: // Remove the duplicate row DataView dv = table. defaultView; table = dv. toTable (true, new string [] {"name", "code"}); in this case, the table has only two

Use editplus to delete duplicate rows in a text file] Http://bbs.dianbo.org/viewthread.php? Tid = 6877 Today, I posted a list of executable commands for running options in the Start Menu. But I found that some rows have been repeated three times, and some rows have only been repeated once or twice. I thought of a

VS2005 has a well-packaged deduplication approach to the DataTable:1 //Remove Duplicate Rows2DataView DV =table. DefaultView;3Table = dv. ToTable (true,New string[] {"name","Code" });4 5 at this point, the table has only name, code no duplicate two lines, if you also need the ID value6 7Table = dv. ToTable (true,New string[] {"Id","name","Code"});//First paramete

When text processing, you often want to delete duplicate rows, here are three ways First, with Sort+uniq, note, simple uniq is not. Sort-n Test.txt | Uniq Second, with the Sort+awk command, note that simply awk also does not, the same reason. [Email protected] ~]$ uniq--help usage: uniq [options] ... [File] Filters adjacent matching rows from the input file

It is mainly used to record the rowid uniqueness of rows in Oracle. Remove duplicate records (pay attention to multiple executions until the impact record is 0 rows) Delete from WBH_TEMP2 where terminal_id in ( Select terminal_id from WBH_TEMP2 group by terminal_id having count (*)>1) And rowid in (select max (rowi

Delete a repeated DataTable column. Only duplicate rows in one of the columns are deleted. One datatable ColumnVs2005 has encapsulated deduplication methods for datatable: 1 // remove duplicate rows 2 DataView dv = table. defaultView; 3 table = dv. toTable (true, new string

Take PostgreSQL 9.2 official document as an example: Create table weather (City varchar (80 ),Temp_lo int, -- low temperatureTemp_hi int, -- high temperaturePrcp real, -- precipitationDate); Insert into weather VALUES('San Francisco ', 46, 50, 0.25, '2017-11-27 '),('San Francisco ', 43, 57, 0, '2017-11-29 '),('Hayward ', 37, 54, NULL, '2017-11-29 '),('Hayward ', 37, 54, NULL, '2017-11-29'); --- duplicated row Here are the three methods: Method 1: Replacement --

than onceDelete data:Delete from studentGROUP BY NumHaving count (num) >1In this case, all the duplicates are deleted.3. Using the distinct method-useful for small tablesCREATE TABLE Table_new as SELECT DISTINCT * FROM table1 MinuxTRUNCATE TABLE table1;INSERT INTO table1 select * from Table_new;The method of querying and deleting duplicate records. Reference Links: How do SQL statements

VS2005 has been encapsulated for the DataTable to repeat the method: Copy Code code as follows: Remove Duplicate rows DataView dv = table. DefaultView; Table = dv. ToTable (True, new string[] {"Name", "Code"}); At this point, the table has only two lines of name, code without duplicates, and if the ID value is required Table = dv. T

described in two parts: user_id and ID. I. Check user_id first 1. The effects of Count (ID) and count (user_id) after group by user_id are different. The following statement indicates that three rows of user_id are null, and count (null) seems invalid. 2. Make the userid in (null, 1257646) and user_id in (1257646) statements consistent, and the previous null will be ignored. In fact, all results are user_id in (1257646 ). Can it be u

Delete duplicate rows in the file It is actually a very simple operation. It is written here because I have been readingThinking in C ++ Volume 2For the iostream chapter, as an exercise, so write it out. J Define constants first Const int unique_lines_ OK = 0; Const int unique_lines_error = 1; Const int file_open_error = 2;

A recently written data collection program generates a file containing more than million rows of data. The data consists of four fields, and the second field must be deleted as required, no suitable tool was found in linux. stream processing tools such as sed/gawk can only process one row but cannot find rows with duplicate fields. It seems that I had to use a py