how to eliminate duplicate records in sql

Http://www.jb51.net/article/34820.htm\1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to determineCopy CodeThe code is as follows:SELECT * from Peoplewhere Peopleid in (select Peopleid from People GROUP by Peopleid have count(Peopleid) > 1)2, delete redundant records

How can I use an SQL statement to delete the same records in a table? Delete duplicate data I. Primary KeyA. Unique field ID (unique primary key)Delete tableWhere id not in(Select max (ID) from Table group by col1, col2, col3...)The field followed by the group by clause is the condition for you to judge repetition, such as only col1,If the content of the col1 fi

Select top n * from table order by id desc -- first sort by id, then obtain the first n, and return an ordered set sorted by id[NOTE: When sorting by an attribute, it is best that the values of the data column in this sorting attribute are not repeated. If there are duplicate values, the order of the rows with the same sorting attribute values in the result set cannot be determined beforehand]Chestnuts are as follows ~ We use pid as the sorting at

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

Tags: style http color using data for AR DivSQL statement method to delete all records in a tableHow to delete all the records in a table with an SQL statement, share my method here.Reference Links: How do SQL statements remove duplicate

In most applications, it is common to return a large number of qualified records. The most typical method is to search. In the search application, the user gives the search criteria and the server finds the matching records. However, a search usually returns a large amount of data records. If you are on a webpage, the page is usually implemented by pagination. Th

In most applications, it is common to return a large number of qualified records. The most typical method is to search. In the search application, the user gives the search criteria and the server finds the matching records. However, a search usually returns a large amount of data records. If you are on a webpage, the page is usually implemented by pagination. Th

enumeration ABirthday DATE,--Birthday -Tel VARCHAR ( One) --Telephone -);② Data Query Language (DQL): queries for data in the database1 -- query All genders DISTINCT represents the removal of duplicate columns 2SELECT DISTINCT sex from t_student; 3 4 --Querying all the data in the table, * representing all columns in the query table 5 SELECT * from t_student; 6 7 -- Query the first start of the data, showing 3 re