Details about duplicate rows

This article mainly introduces some complex sql statements of Mysql (querying and deleting duplicate rows). Friends in need can refer to the following 1. Find duplicate rows SELECT * FROM blog_user_relation a WHERE (a.account_instance_id, a.follow_account_instance_id ) IN (SELECT account_instance_id, follow_account_instance_id FROM blog_user_relation GROUP BY account_instance_id, follow_account_instance_id HAVING COUNT(*) >

1. Mysql Some complex sql statements (query and delete duplicate rows)

Introduction: This article mainly introduces some complex sql statements of Mysql (querying and deleting duplicate rows). Friends who need it can refer to it

2. Some complex sql statements for querying and deleting duplicate rows in Mysql

Introduction: This article mainly introduces some complex sql statements of Mysql (querying and deleting duplicate rows). Friends in need can refer to

3. Through nginx Log statistics of the number of independent ips The command can filter out duplicate lines in text files and perform statistics and other functions. It also accepts input from pipes. With awk, you can even operate on the columns in the row, such as counting the number of independent IPs in nginx log information, listing the IPs with the most visits, etc. What needs to be noted is that uniq only processes connected rows, so generally the sort operation must be performed first. Suppose there is a text file named test.txt, whose information is: ab ac ab ac ac ad ac executes the command uniq test.txt this

4. Delete lines with duplicate fields in the big data file under Linux

Introduction: A data collection program I wrote recently generated a file containing more than 10 million rows of data. The data consists of 4 fields. According to the requirements, rows with duplicate fields in the second field need to be deleted. Find Find

5. mysql query for unique row content and number of unique records.count,distinct

Introduction: There is such a table that records id, p_id, p_name, p_content, p_time 1 343 aaa aaaaaa 2012-09-01 2 344 bbb bbbbbb 2012-09-02 3 321 ccc cccccccc 2012-09-03 4 343 aaa aaaaaa 2012 -09-04 I want to query the contents of non-duplicate rows and output p_sum (the number of times the product p_id is repeated) sele

6. Delete duplicate rows in oracle

Introduction: In daily work, you may encounter that when trying to create a unique index on a certain column or columns in a library table, the system prompts ORA-01452: Unable to create a unique index. Duplicate records found. The principle of deleting duplicate records: (1). In Oracle, each record has a rowid. The rowid is unique in the entire database. The rowid determines whether each record is in Oracle

7. Relational operations in database

##Introduction: 1. Union ) operation, for rows, merge the two tables with the same attributes. If duplicate rows are encountered during the merging process, just keep one item. 2. Difference operation, for the row vc3Ryb25nPjwvcD4KPHA+PHN0cm9uZz4gICAgICA8L3N0cm9uZz7V67bUwb3Vxb7f09DP4M2syvQg0NS1xLHto6y12tK71

8.

SQL statement skills to remove duplicate rows

Introduction: To remove duplicate row data in a table, you may immediately think of using the DISINTCT keyword, but DISINTCT can only remove rows with the same columns in the table. If you need to remove multiple rows in the table, There are rows with duplicate fields (that is, some are the same and some are different), so what should I do? Through many years of database writing experience, I have compiled the following methods for your reference

9. mysql query for unique row content, unique record count, distinct_MySQL

Introduction: mysql query for unique row content, count of unique records, distinct

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