SQL statement Query Results Merge UNION ALL usage _ database Tips

--Merge duplicate rows select * FROM Aunion SELECT * from b--do not merge duplicate rows select * FROM Aunion allselect * from B Sort by a field-merge duplicate row select *from (sele  CT * FROM Aunion select * to B) as Torder by field name--Do not merge duplicate rows select *from (SELECT * FROM Aunion allselect * from B) as Torder By field name//sql Server version SELECT * FROM (select top 2 id,adddate,title,url from barticle where classid=1 order by adddate Desc) Aunion Allselect * FROM (select top 2 id,adddate,title,url from barticle where classid=2 order by adddate Desc) bunion All SELECT * FROM (select top 2 id,adddate,title,url from barticle where classid=3 order by adddate Desc) cunion Allselect * F  Rom (select top 2 id,adddate,title,url from barticle where classid=4 order by adddate Desc) d//mysql Edition select * FROM (SELECT Id,adddate,title,url from Barticle where classid=1 order by adddate desc-limit 0,2) aunion Allselect * FROM (select Id,ad Ddate,title,url from Barticle where classid=2 order by adddate desc-limit 0,2) bunion Allselect * FROM (select Id,adddate, Title,url from Barticlewhere classid=3 ORDER BY adddate desc limit 0,2) cunion Allselect * FROM (select Id,adddate,title,url from Barticle where classid=4 ORDER BY adddate desc limit 0,2) D

SQL statement Query Results Merge UNION ALL usage _ database Tips