delete duplicate rows in sql

User_student (St_name,class,score)Values (' Zhang Si ', ' a ', ' 65 ')Insert into User_student (St_name,class,score)VALUES (' Five ', ' a ', ' 88 ')Insert into User_student (St_name,class,score)VALUES (' Lie triple ', ' B ', ' 97 ')Insert into User_student (St_name,class,score)VALUES (' John Doe ', ' B ', ' 88 ')Insert into User_student (St_name,class,score)VALUES (' Lee ', ' B ', ' 78 ')Insert into User_student (St_name,class,score)VALUES (' Wang San ', ' C ', ' 86 ')Insert into User_student (

Recently, I have been sorting out the database of my website. The database is mysql. Because of the increasing access function, I imported access and reviewed the SQL. There are a lot of data, 0.15 million records, about 1 GB. The two fields a and B of some data are repeated, so that duplicate rows can be considered as duplicated data, as long as any row is retai

In a table, some fields are not primary keys and are not unique, but in the process of use, the field does not apply duplicates, and sometimes it repeats. So, to find the row for a repeating field, use the SQL statement:--That is:--select * from table Where repeating field in (Select repeating field from table Group by repeating field having Count (*) >1)--to a specific example Select * from T_exte RM where Mainkeyindex in (select Mainkeyindex from T_

Method 1 Delete yourtable where [id] not in ( Select MAX ([id]) from yourtable Group by (name + Valu) E) Method 2 Delete a from table a LEFT join ( Select (ID) from table GROUP by Name,value ) b on A.id=b.id Where b.id is null Query and delete duplicate records SQL s

1. Querying duplicate Record single fieldsSELECT * from TBL a where exists (select 1 to tbl B where A.username=b.username GROUP by username have count (*) > 1)2. Number of query repetitionsSelect Clistname,count (clistname) from Clalist GROUP by Clistname have Count (*) >13. Delete duplicate records, leaving ROWID minimum recordsDelete from peoplewhere Peopleid i

SQL Duplicate record query 1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to judge SELECT * from people where Peopleid to (select Peopleid from People GROUP by Peopleid have count (Peopleid) > 1) Case Two: SELECT * from TestTable where Numeber to (select number from people group by nu

Tags: blog http sp c log r AD BSWith such a problem, a SQL statement is used to query the names of students who have more than 80 points per course.Here is the tableAnalysis, query each course is more than 80 students. SELECT DISTINCT name from dbo.student WHERE fenshuStatements less than or equal to 80 select name from Dbo.student WHERE fenshuThis is repeated, and it is worthwhile to use the words in the not-in (no-time) statement to spell the two se

SQL statement for mysql to delete duplicate data and mysql to delete data Create table tmp as select id FROM get_review_url WHERE (no, title, name, content) IN (SELECT no, title, name, content FROM get_review_url group by no, title, name, content having count (*)> 1) AND id not in (select min (id) FROM get_review_url

emp_name salary ------------------------------------------------------------ 1 sunshine 10000 2 semon 20000 SQL> select * from employee E1 Where rowid in (select max (rowid) from employe E2Where e1.emp _ id = e2.emp _ id and E1.emp _ name = e2.emp _ name and e1.salary = e2.salary ); Emp_id emp_name salary ------------------------------------------------------------ 1 sunshine 10000 3. XYZ 30000 2 semon 20000 2.