sql query to remove duplicates

Knss2009.dbo.yw_kck')Select * fromYw_kck++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++data operations between different server databases--create a linked server execsp_addlinkedserver'ITSV',' ','SQLOLEDB','remote server name or IP address' execsp_addlinkedsrvlogin'ITSV','false',NULL,'User name','Password' --Query Example Select * fromitsv. Database name. dbo. Table name--Import Sample Select * intoTable fromitsv. Database name.

SQL statement: Querying information for a single fieldSELECT from WHERE like ('2_');Then, since this is a statement in the stored procedure, the compilation does not report an error while executing the stored procedure, but the execution is reported incorrectly: Operand should contain 1 column (s); reason is not good explanation;Here is the official explanation (MYSQL): https://dev.mysql.com/doc/refman/5.0/en/row-subqueries.htmlSimilar may be report

1. Obtain the first row of data in the table select top 1 * from Dept 2. display a specific row in the first row select DeptNO,DeptName,Phone,Manager,Deputy,Remark from dept where parentID='3' order by case when deptNO='3' then 0 else 1 end 3. SQL nested Query select a,b,c from tableD where a=(select a from tableD) select * from table1 where field1 in (select field1 from table2 where field2 in

How can we query the information of different tables together when we talk about the inefficiency of the related sub-queries in the previous blog post? This requires a table join.Unlike the previous union query, the Union combines different tables, that is, vertical joins, which are spelled upright.A table join is a horizontal join of a table through a Cartesian product, and the so-called Cartesian product

Preface The best way to learn is practice! Therefore, my learning is based on practice. The most basic SQL statement is the query statement. Therefore, I also learned from the select statement. (In fact, this part of the author) has been mastered, but it is still necessary to grasp it again. For the previous study, we mainly used some existing tables in the Oracle database. Here I use Scott as a classic use

.distinct Remove the duplicate instance Code query teacher All units are not duplicated depart column. Select from Teacher Linq: from in teachers.distinct () Select t.depart Lambda: = T.depart) 4. Connection query between and instance Code queries all records in the score table that have scores between 60 and 80. Select* fromScorewheredegree bet

}) View Code 3.distinct Remove the duplicate instance Code query teacher All units are not duplicated depart column. Select from Teacher Linq: from in teachers.distinct () Select t.depart Lambda: = T.depart) View Code 4. Connection query between and instance Code queries all records in the score table that have scores between 60 and 80. Sel

can have no keys and rows are not necessarily unique, in which case the table is not a collection, but a multiset (multiset) or package (bag). But even if the table being queried has a primary key and meets the conditions of the collection, a select query against the table may still return a result that contains duplicates. The result set is often used when describing the output of a select

Original address: http://www.cnblogs.com/ginponson/p/5746435.htmlAssuming that this is page pageno, there are pagesize records per page, and now the student table is queried using MySQL, Oracle, and SQL Server paging.Paging Query for 1.MysqlSELECT * from Student -1* pagesize,pagesize;Understanding: (Limit n,m) + starts from the nth line to fetch M Records, n from 0 to calculate.Paging

. If you have one of the following tables: Table name ID URL Title Content In this table, the title section of the first and second records has a space, and if we don't know, or because of the inability of the content, there is a lot of uncertainty about whether or not there are spaces: The code is as follows SELECT * FROM table where title = ' Li Yang technology blog ';SELECT * FROM table where title like '% Li Yang technology blog% '; The above two

Tags: bracket ROM query SQL statement from Ora reason here sqlFor example: SELECT ename, Job, Deptno from emp WHERE Deptno in (Ten) NB sp; and (ename like '%I ' or job like '%er '); The executes the SQL with the following result set: 1 jones manager NBS P 2 clark manager Remove the upper s

Common SQL Server date comparison and date query statements In SQL Server, you may need to obtain the current date and calculate some other dates. For example, your program may need to determine the first or last day of a month. Most of you probably know how to divide a date (year, month, day, and so on ), then, just use the split year, month, and day to calculat

= @TotalCount outputselect @TotalCount as N ' @TotalCount ' SELECT ' Return Value ' = @return_valueExecution Plan:See the time is really fast, execution plan shows 4 queriesQuery 1, is the use of system tables to get sort fields, types and precision, this quickly, all index.Query 2, return the total number of records, the first time will be slow, and soon after.Query 3 and Query 4 (used to index) is the data we want to page,

First, execute SQL query directly: 1, mappers document extracts 2. DAO class Excerpt public interface somedao{ list 3. Attention Matters 3.1: Parameter sql of the incoming method must follow the following specification "Select XXX as Instanceid, xxx as instancename ..." or MyBatis cannot automatically turn the

in the table Mysql>show columns from TABLE01; Field invalid Null Key Default Extra FIELD01 Int (one) YES FIELD02 Char YES 7. Table Data Fill in Inserting data Mysql>insert into Table01 (FIELD01, FIELD02) VALUES (1, ' a '); Query OK, 1 row Affected (0.00 sec) 8. Increase of fields ... One field at a time Mysql>alter table table01 Add Column field03 char (20); Query OK, L row affected (0.04 sec) Records:1

1. Using OpenDataSourceSelect top *from opendatasource (' SQLOLEDB ', ' Data source=ip address; User id= connection name; password= Connect user password '). Remote target database. dbo. Table name2. Using a junction server--Create Linkserverexec sp_addlinkedserver ' alias ', ' ', ' SQLOLEDB ', ' IP address '--Landing Linkserverexec sp_addlinkedsrvlogin ' Alias ', ' false ', NULL, ' Connect user name ', ' Connect user password '--QuerySELECT * from alias. Library name. dbo. Table name--

-right join: The right connection is to remove all data from the right table, regardless of whether the table on the left has matching data: Select S.name,m.mark from student s right join Mark M on S.id=m.studentid The above statement takes all the data from the Mark score table, regardless of whether there is a data match in the student table, as shown in: Iv. fully connected-full join: Remove the data f

: The right connection is to remove all data from the right table, regardless of whether the table on the left has matching data: Select S.name,m.mark from student s right join Mark M on S.id=m.studentid The above statement takes all the data from the Mark score table, regardless of whether there is a data match in the student table, as shown in: Iv. fully connected-full join: Remove the data from the lef

data: Select S.name,m.mark from student s rightjoin Mark M on S.id=m.studentid The above statement takes all the data from the Mark score table, regardless of whether there is a data match in the student table, as shown in: Iv. fully connected-full join: Remove the data from the left and right two tables, whether or not they match: Select S.name,m.mark from student s fulljoin Mark M on S.id=m.studentid As shown, the data for the student and score ta

field) >1) 3. It's very easy to do a delete update on duplicate records. For example, keep only one of the minimum IDsDelete data table where ID in (the Select Max (ID) from packet Group by repeating record field has count (heavy Complex record field) >1)Update Operation No, it's the same. 4.group by field having count and distinct difference DISTCT query shows that all field values are the same, one record For exampleID Name Sex43 111 144 111 145 11