duplicate

 Delete duplicate records (keep last duplicate data): Delete table where primary key ID not in (select MAX ([primary key ID]) from table group by (duplicate field one + duplicate field two)) Delete duplicate records (keep first duplicate

Share the following method of deleting duplicate records in a database with an SQL statement.For example, there is now a person table (table name: peosons)If you want to name, ID, address, the three fields exactly the same record querySelect p1.*

This is often the case when developing databases:When a piece of data does not exist, insert the data. If the primary key of the data already exists in the database, update the data.How do you do this? First, query data based on the primary key, and

This article refers to the link: http://blog.csdn.net/jbboy/article/details/46828917"I think the article is more suitable for learning and reference, it is worth a look"This article to provide you with three kinds of in MySQL to avoid repeated

This article to provide you with three kinds of in MySQL to avoid repeated insertion record method, mainly refers to the Ignore,replace,on DUPLICATE key update three methods, you can try to reference.Case one: Using the Ignore keywordIf the

Find records for all repeating headings:SELECT *From T_info AWHERE (SELECT COUNT (*)From T_infoWHERE Title = a.title) > 1)ORDER by Title DESCOne. Find Duplicate Records1. Find all duplicate recordsSELECT * FROM table Where repeating field in (Select

For example:ID Name Value1 a pp2 a PP3 B III4 B pp5 B pp6 C pp7 C pp8 C IIIID is primary keyAsk for such a resultID Name Value1 a pp3 B III4 B pp6 C pp8 C IIIMethod 1Delete yourtablewhere [id] not in (Select MAX ([id]) from yourtableGroup BY (name +

Find records for all repeating headings:SELECT * from T_info a WHERE ((SELECT COUNT (*) from t_info where Title = A.title) > 1) ORDER by Title DESCOne.find a repeating recordRecorded1. Find all duplicate recordsSELECT * FROM table Where repeating

Case one: Use the Ignore keyword If the uniqueness of the record is distinguished by the primary key primary or unique index unique, it is possible to avoid duplicate insertion records: The code is as follows Copy Code 1

Microsoft SQL Server tables should not contain duplicate rows and non-unique primary keys. For brevity, in this article we sometimes call the primary key "key" or "PK", but this always represents "primary key". Duplicate PK violates entity integrity

Original article: http://support.microsoft.com/kb/139444/SummaryThe Microsoft SQL Server table should not contain duplicate rows and non-unique primary keys. For the sake of conciseness, we sometimes refer to the primary key as "key" or "Pk" in this

MySQL prevent duplicate Insert Record method summaryThere are many ways to prevent MySQL from repeatedly inserting records, usually Ignore,replace,on DUPLICATE KEY UPDATE, which we can also judge in PHP.Scenario One: Using the Ignore keywordIf the

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

This article to provide you with three kinds of in MySQL to avoid repeated insertion record method, mainly refers to the Ignore,replace,on DUPLICATE key update three methods, you can try to reference.Case one: Using the Ignore keywordIf the

Find records for all duplicate headings: ? 1 SELECT * from T_info a WHERE (SELECT COUNT (*) from t_info where title = A.title) > 1) Order by Title DESC First, find duplicate records 1. Find all duplicate records ?

The Microsoft SQL Server table should not contain duplicate rows and non-unique primary keys. For the sake of conciseness, we sometimes refer to the primary key as "key" or "PK" in this article, but this always indicates "primary key ". Repeated PK

Although the SQL statements for querying and deleting duplicate records are messy, the content is still good. Although the SQL statements for querying and deleting duplicate records are messy, the content is still good. For example: Id name value 1

The SQL statement I used: Delete from fp_sgfpxxWhere fphm in (select fphm from fp_sgfpxx group by fphm having count (fphm)> 1)And rowid not in (select min (rowid) from fp_sgfpxx group by fphm having count (fphm)> 1) Delete duplicate invoice

For example: ID Name Value 1 a pp 2 a PP 3 B III 4 B pp 5 B pp 6 C pp 7 C pp 8 C III ID is primary key Ask for such a result ID Name Value 1 a pp 3 B III 4 B pp 6 C pp 8 C III Method 1 Delete yourtable where [id] not in ( Select MAX ([id]) from

How does mysql Delete duplicate record statements ?? For example, idnamevalue1app2app3biii4bpp5bpp6cpp7cpp8ciiiid is the primary key required to obtain this result idnamevalue1app3biii4bpp6cpp8ciii method 1 deleteYourTable How does mysql Delete