联合主键 去重复记录的方法

方法1、 就是将三个字段连接起来作为主键，进行数据是否重复的判断。这里值得注意的是某列的值可能为空，所以要赋一个空字符串过去： select * from t1 where nvl(col1,'')|| nvl(col2,'')|| col3 not in (select col1||col2||col3 from t2) 方法2、 统计多表联合查询 去重复记录的方法 两表结构不一样，或者一样的，多个表结合起来查询的，都可以 1. --> 生成测试数据表:a 2. 3. IF NOT OBJECT_ID('[a]') IS NULL 4. DROP TABLE [a] 5. GO 6. CREATE TABLE [a]([id] INT,[name] NVARCHAR(10),[parentid] INT) 7. INSERT [a] 8. SELECT 1,'area',0 UNION ALL 9. SELECT 2,'category',0 UNION ALL 10. SELECT 3,'north',1 UNION ALL 11. SELECT 4,'south',1 UNION ALL 12. SELECT 5,'Shanghai',4 UNION ALL 13. SELECT 6,'Beijing',3 UNION ALL 14. SELECT 7,'pudong',5 UNION ALL 15. SELECT 8,'xuhui',5 UNION ALL 16. SELECT 9,'chaoyang',6 UNION ALL 17. SELECT 10,'desk',2 UNION ALL 18. SELECT 11,'chair',2 UNION ALL 19. SELECT 12,'bed',2 20. GO 21. 22. --> 生成测试数据表:b 23. 24. IF NOT OBJECT_ID('[b]') IS NULL 25. DROP TABLE [b] 26. GO 27. CREATE TABLE [b]([id] INT,[area] INT,[city] INT,[district] NVARCHAR(10)) 28. INSERT [b] 29. SELECT 1,4,5,'pudong' UNION ALL 30. SELECT 2,4,5,'xuhui' UNION ALL 31. SELECT 3,4,6,'chaoyang' 32. GO 33. --> 生成测试数据表:c 34. 35. IF NOT OBJECT_ID('[c]') IS NULL 36. DROP TABLE [c] 37. GO 38. CREATE TABLE [c]([id] INT,[category] INT,[area] INT,[city] INT,[district] INT) 39. INSERT [c] 40. SELECT 1,10,4,5,7 UNION ALL 41. SELECT 2,10,4,5,7 UNION ALL 42. SELECT 3,11,4,5,8 UNION ALL 43. SELECT 4,11,3,6,9 UNION ALL 44. SELECT 5,10,3,6,9 45. GO 46. 47. -->SQL查询如下: 48. --SELECT * FROM [a] 49. --SELECT * FROM [b] 50. --SELECT * FROM [c] 51. 52. -->SQL查询如下: 53. select a0.name area, 54. a1.name city, 55. a2.name district, 56. '' address, 57. MAX(case a3.name when 'desk' then 数量 else 0 end) 桌子数量, 58. MAX(case a3.name when 'chair' then 数量 else 0 end) 椅子数量, 59. MAX(case a3.name when 'bed' then 数量 else 0 end) 床数量 60. from ( 61. select category,area,city,[district],COUNT(1) 数量 62. from c 63. group by category,area,city,[district] 64. ) c 65. join a a0 on a0.id=c.area 66. join a a1 on a1.id=c.[city] 67. join a a2 on a2.id=c.district 68. join a a3 on a3.id=c.category 69. left join b on b.area=c.area and c.city=b.city 70. group by a0.name,a1.name,a2.name 71. /* 72. area city district address 桌子数量 椅子数量 床数量 73. ---------- ---------- ---------- ------- ----------- ----------- ----------- 74. north Beijing chaoyang 1 1 0 75. south Shanghai pudong 2 0 0 76. south Shanghai xuhui 0 1 0 77. 78. (3 行受影响) 79. */ 1. --处理表重复记录(查询和删除) 2. /****************************************************************************************************************************************************** 3. 1、Num、Name相同的重复值记录,没有大小关系只保留一条 4. 2、Name相同,ID有大小关系时,保留大或小其中一个记录 5. 整理人：中国风(Roy) 6. 7. 日期:2008.06.06 8. ******************************************************************************************************************************************************/ 9. 10. --1、用于查询重复处理记录(如果列没有大小关系时2000用生成自增列和临时表处理,SQL2005用row_number函数处理) 11. 12. --> --> (Roy)生成測試數據 13. 14. if not object_id('Tempdb..#T') is null 15. drop table #T 16. Go 17. Create table #T([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2)) 18. Insert #T 19. select 1,N'A',N'A1' union all 20. select 2,N'A',N'A2' union all 21. select 3,N'A',N'A3' union all 22. select 4,N'B',N'B1' union all 23. select 5,N'B',N'B2' 24. Go 25. 26. 27. --I、Name相同ID最小的记录(推荐用1,2,3),方法3在SQl05时，效率高于1、2 28. 方法1: 29. Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID 30. 31. 方法2: 32. select a.* from #T a join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID 33. 34. 方法3: 35. select * from #T a where ID=(select min(ID) from #T where Name=a.Name) 36. 37. 方法4: 38. select a.* from #T a join #T b on a.Name=b.Name and a.ID>=b.ID group by a.ID,a.Name,a.Memo having count(1)=1 39. 40. 方法5: 41. select * from #T a group by ID,Name,Memo having ID=(select min(ID)from #T where Name=a.Name) 42. 43. 方法6: 44. select * from #T a where (select count(1) from #T where Name=a.Name and ID 45. 46. 方法7: 47. select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID) 48. 49. 方法8: 50. select * from #T a where ID!>all(select ID from #T where Name=a.Name) 51. 52. 方法9(注:ID为唯一时可用): 53. select * from #T a where ID in(select min(ID) from #T group by Name) 54. 55. --SQL2005: 56. 57. 方法10: 58. select ID,Name,Memo from (select *,min(ID)over(partition by Name) as MinID from #T a)T where ID=MinID 59. 60. 方法11: 61. 62. select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID) as MinID from #T a)T where MinID=1 63. 64. 生成结果: 65. /* 66. ID Name Memo 67. ----------- ---- ---- 68. 1 A A1 69. 4 B B1 70. 71. (2 行受影响) 72. */ 73. 74. 75. --II、Name相同ID最大的记录,与min相反: 76. 方法1: 77. Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID>a.ID) 78. 79. 方法2: 80. select a.* from #T a join (select max(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID order by ID 81. 82. 方法3: 83. select * from #T a where ID=(select max(ID) from #T where Name=a.Name) order by ID 84. 85. 方法4: 86. select a.* from #T a join #T b on a.Name=b.Name and a.ID<=b.ID group by a.ID,a.Name,a.Memo having count(1)=1 87. 88. 方法5: 89. select * from #T a group by ID,Name,Memo having ID=(select max(ID)from #T where Name=a.Name) 90. 91. 方法6: 92. select * from #T a where (select count(1) from #T where Name=a.Name and ID>a.ID)=0 93. 94. 方法7: 95. select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID desc) 96. 97. 方法8: 98. select * from #T a where ID! 99. 100. 方法9(注:ID为唯一时可用): 101. select * from #T a where ID in(select max(ID) from #T group by Name) 102. 103. --SQL2005: 104. 105. 方法10: 106. select ID,Name,Memo from (select *,max(ID)over(partition by Name) as MinID from #T a)T where ID=MinID 107. 108. 方法11: 109. select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID desc) as MinID from #T a)T where MinID=1 110. 111. 生成结果2: 112. /* 113. ID Name Memo 114. ----------- ---- ---- 115. 3 A A3 116. 5 B B2 117. 118. (2 行受影响) 119. */ 1. --分组取其中某字段最小，去重复 2. if object_id('[tb]') is not null drop table [tb] 3. go 4. create table [tb]([EID] varchar(2),[OID] varchar(2),[Value] int) 5. insert [tb] 6. select 'E1','O1',4 union all 7. select 'E2','O2',16 union all 8. select 'E3','O1',5 union all 9. select 'E4','O2',8 union all 10. select 'E5','O1',3 union all 11. select 'E6','O3',9 12. 13. select t1.* from tb t1 14. where EID = ( 15. select top 1 t2. EID from tb t2 16. where t2.Value = ( 17. select min(t3.Value) from tb t3 18. where t2.EID=t3.EID 19. ) and t1.OID=t2.OID 20. ) 21. and t1.EID in ('E1','E2','E4') 1. --按某一字段分组取最大(小)值所在行的数据 2. --(爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开) 2007-10-23于浙江杭州) 3. /* 4. 数据如下： 5. name val memo 6. a 2 a2(a的第二个值) 7. a 1 a1--a的第一个值 8. a 3 a3:a的第三个值 9. b 1 b1--b的第一个值 10. b 3 b3:b的第三个值 11. b 2 b2b2b2b2 12. b 4 b4b4 13. b 5 b5b5b5b5b5 14. */ 15. --创建表并插入数据： 16. create table tb(name varchar(10),val int,memo varchar(20)) 17. insert into tb values('a', 2, 'a2(a的第二个值)') 18. insert into tb values('a', 1, 'a1--a的第一个值') 19. insert into tb values('a', 3, 'a3:a的第三个值') 20. insert into tb values('b', 1, 'b1--b的第一个值') 21. insert into tb values('b', 3, 'b3:b的第三个值') 22. insert into tb values('b', 2, 'b2b2b2b2') 23. insert into tb values('b', 4, 'b4b4') 24. insert into tb values('b', 5, 'b5b5b5b5b5') 25. go 26. 27. --一、按name分组取val最大的值所在行的数据。 28. --方法1： 29. select a.* from tb a where val = (select max(val) from tb where name = a.name) order by a.name 30. --方法2： 31. select a.* from tb a where not exists(select 1 from tb where name = a.name and val > a.val) 32. --方法3： 33. select a.* from tb a,(select name,max(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name 34. --方法4： 35. select a.* from tb a inner join (select name , max(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name 36. --方法5 37. select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name 38. /* 39. name val memo 40. ---------- ----------- -------------------- 41. a 3 a3:a的第三个值 42. b 5 b5b5b5b5b5 43. */ 44. 45. --二、按name分组取val最小的值所在行的数据。 46. --方法1： 47. select a.* from tb a where val = (select min(val) from tb where name = a.name) order by a.name 48. --方法2： 49. select a.* from tb a where not exists(select 1 from tb where name = a.name and val < a.val) 50. --方法3： 51. select a.* from tb a,(select name,min(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name 52. --方法4： 53. select a.* from tb a inner join (select name , min(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name 54. --方法5 55. select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val < a.val) order by a.name 56. /* 57. name val memo 58. ---------- ----------- -------------------- 59. a 1 a1--a的第一个值 60. b 1 b1--b的第一个值 61. */ 62. 63. --三、按name分组取第一次出现的行所在的数据。 64. select a.* from tb a where val = (select top 1 val from tb where name = a.name) order by a.name 65. /* 66. name val memo 67. ---------- ----------- -------------------- 68. a 2 a2(a的第二个值) 69. b 1 b1--b的第一个值 70. */ 71. 72. --四、按name分组随机取一条数据。 73. select a.* from tb a where val = (select top 1 val from tb where name = a.name order by newid()) order by a.name 74. /* 75. name val memo 76. ---------- ----------- -------------------- 77. a 1 a1--a的第一个值 78. b 5 b5b5b5b5b5 79. */ 80. 81. --五、按name分组取最小的两个(N个)val 82. select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val < a.val ) order by a.name,a.val 83. select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val) order by a.name,a.val 84. select a.* from tb a where exists (select count(*) from tb where name = a.name and val < a.val having Count(*) < 2) order by a.name,a.val 85. /* 86. name val memo 87. ---------- ----------- -------------------- 88. a 1 a1--a的第一个值 89. a 2 a2(a的第二个值) 90. b 1 b1--b的第一个值 91. b 2 b2b2b2b2 92. */ 93. 94. --六、按name分组取最大的两个(N个)val 95. select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name,a.val 96. select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val desc) order by a.name,a.val 97. select a.* from tb a where exists (select count(*) from tb where name = a.name and val > a.val having Count(*) < 2) order by a.name , a.val 98. /* 99. name val memo 100. ---------- ----------- -------------------- 101. a 2 a2(a的第二个值) 102. a 3 a3:a的第三个值 103. b 4 b4b4 104. b 5 b5b5b5b5b5 105. */ 106. --七，如果整行数据有重复，所有的列都相同。 107. /* 108. 数据如下： 109. name val memo 110. a 2 a2(a的第二个值) 111. a 1 a1--a的第一个值 112. a 1 a1--a的第一个值 113. a 3 a3:a的第三个值 114. a 3 a3:a的第三个值 115. b 1 b1--b的第一个值 116. b 3 b3:b的第三个值 117. b 2 b2b2b2b2 118. b 4 b4b4 119. b 5 b5b5b5b5b5 120. */ 121. --在sql server 2000中只能用一个临时表来解决，生成一个自增列，先对val取最大或最小，然后再通过自增列来取数据。 122. --创建表并插入数据： 123. create table tb(name varchar(10),val int,memo varchar(20)) 124. insert into tb values('a', 2, 'a2(a的第二个值)') 125. insert into tb values('a', 1, 'a1--a的第一个值') 126. insert into tb values('a', 1, 'a1--a的第一个值') 127. insert into tb values('a', 3, 'a3:a的第三个值') 128. insert into tb values('a', 3, 'a3:a的第三个值') 129. insert into tb values('b', 1, 'b1--b的第一个值') 130. insert into tb values('b', 3, 'b3:b的第三个值') 131. insert into tb values('b', 2, 'b2b2b2b2') 132. insert into tb values('b', 4, 'b4b4') 133. insert into tb values('b', 5, 'b5b5b5b5b5') 134. go 135. 136. select * , px = identity(int,1,1) into tmp from tb 137. 138. select m.name,m.val,m.memo from 139. ( 140. select t.* from tmp t where val = (select min(val) from tmp where name = t.name) 141. ) m where px = (select min(px) from 142. ( 143. select t.* from tmp t where val = (select min(val) from tmp where name = t.name) 144. ) n where n.name = m.name) 145. 146. drop table tb,tmp 147. 148. /* 149. name val memo 150. ---------- ----------- -------------------- 151. a 1 a1--a的第一个值 152. b 1 b1--b的第一个值 153. 154. (2 行受影响) 155. */ 156. --在sql server 2005中可以使用row_number函数，不需要使用临时表。 157. --创建表并插入数据： 158. create table tb(name varchar(10),val int,memo varchar(20)) 159. insert into tb values('a', 2, 'a2(a的第二个值)') 160. insert into tb values('a', 1, 'a1--a的第一个值') 161. insert into tb values('a', 1, 'a1--a的第一个值') 162. insert into tb values('a', 3, 'a3:a的第三个值') 163. insert into tb values('a', 3, 'a3:a的第三个值') 164. insert into tb values('b', 1, 'b1--b的第一个值') 165. insert into tb values('b', 3, 'b3:b的第三个值') 166. insert into tb values('b', 2, 'b2b2b2b2') 167. insert into tb values('b', 4, 'b4b4') 168. insert into tb values('b', 5, 'b5b5b5b5b5') 169. go 170. 171. select m.name,m.val,m.memo from 172. ( 173. select * , px = row_number() over(order by name , val) from tb 174. ) m where px = (select min(px) from 175. ( 176. select * , px = row_number() over(order by name , val) from tb 177. ) n where n.name = m.name) 178. 179. drop table tb 180. 181. /* 182. name val memo 183. ---------- ----------- -------------------- 184. a 1 a1--a的第一个值 185. b 1 b1--b的第一个值 186. 187. (2 行受影响) 188. */