db2 union

SQL UNION operator The UNION operator is used to merge the result sets of two or more SELECT statements. Note:: 1. SELECT statements within UNION must have the same number of columns. Columns must also have similar data types. In addition, the columns in each SELECT statement must be in the same order. 2. The column name in the

matching rows in the right table (table_name2). Select Persons.lastname, Persons.firstname, Orders.orderno from Persons left JOIN Orders on Persons.id_p=orders.id_p ORDER by Persons.lastname The right JOIN keyword returns all rows from the table (table_name2), even if there are no matching rows in the left table (table_name1). SELECT persons.lastname, Persons.firstname, Orders.orderno from Persons right JOIN Orders on Persons.id_p=orders.id_p ORDER by Persons.lastname Full JOIN keyword: The

In the database, the UNION and union all keywords combine the two results into one, but both have different usage and efficiency.UNION in MySQLUNION filters out duplicate records after table link. Therefore, after table link, it sorts the generated result sets and deletes duplicate records before returning results. In most applications, duplicate records are not generated. The most common is the

The difference between union and union all and the use of join 1. The difference between union and union all is www.2cto.com Union. union operations are performed on two result sets, excluding repeated rows, sort the default rules

Federated result set New TEMP Data Sheet Copy Code code as follows: CREATE TABLE T_tempemployee (Fidcardnumber VARCHAR (), FName VARCHAR (), Fage int,primary KEY (fidcardnumber)); INSERT into T_tempemployee (fidcardnumber,fname,fage) VALUES (' 1234567890121 ', ' Sarani ', 33); INSERT into T_tempemployee (fidcardnumber,fname,fage) VALUES (' 1234567890122 ', ' Tom ', 26); INSERT into T_tempemployee (fidcardnumber,fname,fage) VALUES (' 1234567890123 ', ' Yalaha ', 38); INSER

Union is inefficient because it is scanned for duplicate values. If the merge does not intentionally delete duplicate rows, then use UNION ALL Two the number of SQL statement fields to be joined must be the same, and the field type should be "compatible" (consistent); If we need to display the results of the two SELECT statements as a whole, we need the union or

Tags: style http color using IO data ar artdifferences in the Union and Union All in Oracle (for multiple databases)If we need to display the results of the two SELECT statements as a whole, we need to use the union or UNION ALL keyword. Union (or

HDU1116 Play on Words [European Union] + [query set], hdu1116 European Union Play on WordsTime Limit: 10000/5000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission (s): 5736 Accepted Submission (s): 1897 Problem DescriptionSome of the secret doors contain a very interesting word puzzle. the team of archaeologists has to solve it to open that doors. because there is no other way to

The Union operator can combine two or more query results into one result set display. The syntactic format of the unionf operator is:Query 1[union[all] Query N] ...[ORDER BY clause][COMPUTE clause]The format of query 1 to query n is:SELECT select_list[INTO clause][FROM clause][WHERE clause][GROUP by clause]Example: Merge the two query results from the titles table and the discounts table. In a federated

Tags: problem bank table MEM Code Stat SQL NiO from 1 Create TableBuyer as 2 SELECTb.ID asBankID3 fromV_product_deal_main m, Base_member b4 WHEREb.ID=M.buyerid5 andM.dealdateTo_date ('20160630','YYYYMMDD') 6 andM.state= 9 7 andB.state= 0; 8 ---441947 9 --Seller Square TenCreate table seller asSELECT * fromseller; One Create TableSeller as A SELECTb.ID asBankID - fromV_product_deal_main m, Base_member b - WHEREb.ID=M.sellerid the andM.dealdateTo_date ('20160630','YYYY

('Maitreya Buddha','Buddhist', -), +('Buddha Buddha','Buddhist', -), A('Buddhist Bodhisattva','Buddhist', -), the('The Buddha','Buddhist',101)--For convenience, add 1 points to the Bodhisattva + - Insert intoDaojiateacher $ Values('nu wa Niang','Taoism', -), $('Yangmn greedy wolf too star June','Taoism',101), -('Yin Jing giant door Yuan Xing June','Taoism',101), -('Live Lu, the true star','Taoism',101), the('Xuan Ming Wen qu new star June','Taoism',101) - Wuyi the Select * fromDaojiat

Union operates on two result sets, excluding duplicate rows, while ordering the default rules; UNION all sets up and does a set of two result sets, including repeating rows, not sorting Union ALL is much faster than union, so if you can confirm that the merged two result sets do not contain duplicate data, then use

The Union and UNION all are the results and collections that are used to get multiple query statements, and there are some specifications to follow, of course:The internal SELECT statement must have the same number of columns.The column must also have a similar data type.Also, the order of the columns in each SELECT statement must be the same.and the column name takes the column name of the most preceding q

values (' AS3 ', ' 19 ')Insert tab2 values (' As4 ', ' 19 ')GoSELECT * FROM Tab1SELECT * from Tab1 where tab1.bid= ' a ' union ALL select * from tab2 where tab2.bid= ' 19 'The words of the moderator:1. The join produces the Cartesian product.2, union will exclude duplicate records3. Union ALL does not exclude duplicate records The

For exampleFirst, create a, b two tables, in order to facilitate understanding, both tables create only one field column, respectively, A_col and B_col, add a tableData 1, 4, 5, 9, add B table Data 2, 3, 4, 5.Second, enter the following statement: SELECT * FROM A Union SELECT * FROM B;Results: 1, 4, 5, 9, 2, 3. (Remove duplicate rows)Enter the following statement: SELECT * FROM A UNION ALL SELECT * from B;R

Http://hi.baidu.com/wader2006/blog/item/78406b60b51f8b47ebf8f8f0.html DB2 Common Command Set----DB2 maintenance 2007-09-09 10:10 in the DB2 development process, the whole development process also has a very important part of the work is the maintenance of the database, for the maintenance of a huge information system is very necessary; Leave a simple maintenance

Difference between union and union all in mysql, mysqlunion When querying data from multiple tables with identical table structures: 1. when the query conditions are identical and do not include the primary key, the union query will filter out the queried duplicate records and missed records. The union all clause wil

In the database, the UNION and union all keywords combine the two results into one, but both have different usage and efficiency.Several tables are extracted by UNION at runtime.OfResult, and then use the sorting space to sort and delete duplicates.OfRecord, and finally return the result set. If the table has a large amount of dataOfThe disk may be used for sorti

A concise tutorial on SQL statements in linux --- UNION ALL, a concise tutorial --- union UNION ALLThe purpose of this command is to combine the results of two SQL statements.UNION ALLAndUNIONThe difference is thatUNION ALLEach qualified item is listed, regardless of whether the item value is repeated. UNION ALLSyntax:

Union and Union all both display the results of the two select statements as a whole, and combine the two records into a query. However, the premise is that the field names of the selected two tables must be consistent. But there are differences between the two: Union: merges multiple result sets and returns them as a single result set (deduplication and sortin