Delete duplicate records in the Table. Only one row is retained.

1. The SQL statement I used:
2. Delete from fp_sgfpxx
   Where fphm in (select fphm from fp_sgfpxx group by fphm having count (fphm)> 1)
   And rowid not in (select min (rowid) from fp_sgfpxx group by fphm having count (fphm)> 1)
3. Delete duplicate invoice numbers
5. SQL statement used to query Repeated Records of multiple fields in the same table
6. From: 7th string
9. For example, there is a personnel table (table name: peosons)
10. Select p1. * from persons p1, persons p2 where p1.id <> p2.id and p1.cardid = p2.cardid and p1.pname = p2.pname and p1.address = p2.address
11. The above results can be achieved.
12. Several SQL statements used to delete Repeated Records
14. 1. Use the rowid Method
15. 2. Use the group by Method
16. 3. Use the distinct method
18. 1. Rowid Method
19. The statement is as follows:
20. Query data:
21. Select * from table1 a where rowid! = (Select max (rowid)
22. From table1 B where a. name1 = B. name1 and a. name2 = B. name2 ......)
23. Delete data:
24. Delete from table1 a where rowid! = (Select max (rowid)
25. From table1 B where a. name1 = B. name1 and a. name2 = B. name2 ......)
26. 2. group by Method
27. Query data:
28. Select count (num), max (name) from student -- lists the number of repeated records and its name attribute
29. Group by num
30. Having count (num)> 1 -- group by num to find the num column in the table, that is, more than once
31. Delete data:
32. Delete from student
33. Group by num
34. Having count (num)> 1
35. In this way, all duplicates are deleted.
36. 3. Use the distinct method-useful for small tables
37. Create table table_new as select distinct * from table1 minux
38. Truncate table table1;
39. Insert into table1 select * from table_new;
42. How to query and delete duplicate records
44. 1. Search for redundant duplicate records in the Table. duplicate records are determined based on a single field (peopleId ).
45. Select * from people
46. Where peopleId in (select peopleId from people group by peopleId having count (peopleId)> 1)
49. 2. Delete unnecessary duplicate records in the Table. Repeat records are determined based on a single field (eagleid), leaving only the records with the smallest rowid
50. Delete from people
51. Where peopleId in (select peopleId from people group by peopleId having count (peopleId)> 1)
52. And rowid not in (select min (rowid) from people group by peopleId having count (peopleId)> 1)
55. 3. Search for redundant duplicate records in the table (multiple fields)
56. Select * from vitae
57. Where (a. peopleId, a. seq) in (select peopleId, seq from vitae group by peopleId, seq having count (*)> 1)
60. 4. Delete redundant record (multiple fields) in the table, leaving only the records with the smallest rowid
61. Delete from vitae
62. Where (a. peopleId, a. seq) in (select peopleId, seq from vitae group by peopleId, seq having count (*)> 1)
63. And rowid not in (select min (rowid) from vitae group by peopleId, seq having count (*)> 1)
66. 5. Search for redundant duplicate records (multiple fields) in the table, excluding records with the smallest rowid
67. Select * from vitae
68. Where (a. peopleId, a. seq) in (select peopleId, seq from vitae group by peopleId, seq having count (*)> 1)
69. And rowid not in (select min (rowid) from vitae group by peopleId, seq having count (*)> 1)
72. (2)
73. For example
74. There is A field "name" in Table ",
75. The "name" value may be the same for different records,
76. Now, you need to query items with duplicate "name" values between records in the table;
77. Select Name, Count (*) From A Group By Name Having Count (*)> 1
78. If the gender is also the same, the statement is as follows:
79. Select Name, sex, Count (*) From A Group By Name, sex Having Count (*)> 1
82. (3)
83. Method 1
84. Declare @ max integer, @ id integer
85. Declare cur_rows cursor localForSelect Main field, count (*) from table name group by main field having count (*)>; 1
86. Open cur_rows
87. Fetch cur_rows into @ id, @ max
88. While@ Fetch_status = 0
89. Begin
90. Select @ max = @ max-1
91. Set rowcount @ max
92. Delete from table name where primary field = @ id
93. Fetch cur_rows into @ id, @ max
94. End
95. Close cur_rows
96. Set rowcount 0
99. Method 2
100. "Repeat record" has two duplicate records. One is a completely repeated record, that is, a record with all fields already exists. The other is a record with duplicate key fields, for example, the Name field is repeated, while other fields are not necessarily repeated or can be ignored.
103. 1. For the first type of repetition, it is easier to solve.
104. Select distinct * from tableName
105. You can get the result set without repeated records.
106. If the table needs to delete duplicate records (one record is retained), you can delete the record as follows:
107. Select distinct * into # Tmp from tableName
108. Drop table tableName
109. Select * into tableName from # Tmp
110. Drop table # Tmp
111. The reason for this repetition is that the table design is not weekly. You can add a unique index column.
114. 2. Repeat problems usually require that the first record in the repeat record be retained. The procedure is as follows:
115. Assume that the duplicate fields are Name and Address. You must obtain the unique result set of the two fields.
116. Select identity (Int, 1, 1) as autoID, * into # Tmp from tableName
117. Select min (autoID) as autoID into # Tmp2 from # Tmp group by Name, autoID
118. Select * from # Tmp where autoID in (select autoID from # tmp2)
119. The last select command gets the result set with no duplicate Name and Address (but an autoID field is added, which can be omitted in the select clause when writing)
122. (4)
123. Duplicate Query
124. Select * from tablename where id in (
125. Select id from tablename
126. Group by id
127. Having count (id)> 1
128. )
129. ======================================

131. There are several identical records in thousands of records. How can I use SQL statements to delete duplicates? Thank you!
     1. Search for redundant duplicate records in the Table. duplicate records are determined based on a single field (peopleId ).
     Select * from people
     Where peopleId in (select peopleId from people group by peopleId having count (peopleId)> 1)

     2. Delete unnecessary duplicate records in the Table. Repeat records are determined based on a single field (eagleid), leaving only the records with the smallest rowid
     Delete from people
     Where peopleId in (select peopleId from people group by peopleId having count (peopleId)> 1)
     And rowid not in (select min (rowid) from people group by peopleId having count (peopleId)> 1)

     3. Search for redundant duplicate records in the table (multiple fields)
     Select * from vitae
     Where (a. peopleId, a. seq) in (select peopleId, seq from vitae group by peopleId, seq having count (*)> 1)

     4. Delete redundant record (multiple fields) in the table, leaving only the records with the smallest rowid
     Delete from vitae
     Where (a. peopleId, a. seq) in (select peopleId, seq from vitae group by peopleId, seq having count (*)> 1)
     And rowid not in (select min (rowid) from vitae group by peopleId, seq having count (*)> 1)

     5. Search for redundant duplicate records (multiple fields) in the table, excluding records with the smallest rowid
     Select * from vitae
     Where (a. peopleId, a. seq) in (select peopleId, seq from vitae group by peopleId, seq having count (*)> 1)
     And rowid not in (select min (rowid) from vitae group by peopleId, seq having count (*)> 1)

     For example, there is A field "name" in Table A, and the "name" values may be the same between different records,
     Now, you need to query items with duplicate "name" values between records in the table;
     Select Name, Count (*) From A Group By Name Having Count (*)> 1

     If the gender is also the same, the statement is as follows:
     Select Name, sex, Count (*) From A Group By Name, sex Having Count (*)> 1

     2. group by Method

     Query data:
     Select count (num), max (name) from student -- lists the number of repeated records and its name attribute
     Group by num
     Having count (num)> 1 -- group by num to find the num column in the table, that is, more than once
     Delete data:
     Delete from student
     Group by num
     Having count (num)> 1
     In this way, all duplicates are deleted.

     3. Use the distinct method-useful for small tables

     Create table table_new as select distinct * from table1 minux
     Truncate table table1;
     Insert into table1 select * from table_new;

     Delete select a. * from FLRK1 a inner join FLRK1 B on a. Record Number = B. Record Number and
     (A. [ID] = B. [ID] and a. warehouse receiving date = B. warehouse receiving date and a. operation time = B. Operation Time)

     Delete from FLRK1 where record number in
     (Select min (Record Number) from FLRK1 group by record number having count (Record Number)> 1)

     Table A structure:

     ID RQ SJ C
     --------------------------------------------
     1 2005-07-14 14:20:50 A1
     2 05:12:23 A1
     3 2005-07-14 14:20:50 A1
     4 2005-06-16 16:16:16 A2
     5 16:16:16 A2
     6 05:10:35 A3
     7 05:12:23 A1

     --------------------------------------------

     Find one SQL statement and delete the same record for the RQ, SJ, and C fields in table.

     Result:

     ID RQ SJ C
     --------------------------------------------
     1 2005-07-14 14:20:50 A1
     2 2005-02-15 05:12:23 A1
     4 2005-06-16 16:16:16 A2
     6 05:10:35 A3
     --------------------------------------------

     Delete from A Where ID Not In (Select Min (ID) from A Group By RQ, SJ, C)

     Delete a from tb a inner join tb as B on. fid <B. fid and. c = B. c and. rq = B. rq and. sj = B. sj

     Delete from A t
     Where exists (select 1 from A where ID <A. ID and SJ = t. SJ and RQ = t. RQ and C = t. c)

     Method 1

     Declare @ max integer, @ id integer
     Declare cur_rows cursor local for select Main field, count (*) from table name group by main field having count (*)> 1
     Open cur_rows
     Fetch cur_rows into @ id, @ max
     While fetch_status = 0
     Begin
     Select @ max = @ max-1
     Set rowcount @ max
     Delete from table name where primary field = @ id
     Fetch cur_rows into @ id, @ max
     End
     Close cur_rows
     Set rowcount 0

     Method 2

     There are two Repeated Records. One is a completely repeated record, that is, records with all fields being repeated, and the other is records with duplicate key fields, such as duplicate Name fields, other fields are not necessarily repeated or can be ignored.

     1. For the first type of repetition, it is easier to solve.

     Select distinct * from tableName

     You can get the result set without repeated records.
     If the table needs to delete duplicate records (one record is retained), you can delete the record as follows:

     Select distinct * into # Tmp from tableName
     Drop table tableName
     Select * into tableName from # Tmp
     Drop table # Tmp

     The reason for this repetition is that the table design is not weekly. You can add a unique index column.

     2. Repeat problems usually require that the first record in the repeat record be retained. The procedure is as follows:

     Assume that the duplicate fields are Name and Address. You must obtain the unique result set of the two fields.

     Select identity (int, 1, 1) as autoID, * into # Tmp from tableName
     Select min (autoID) as autoID into # Tmp2 from # Tmp group by Name, autoID
     Select * from # Tmp where autoID in (select autoID from # tmp2)

     The last select command gets the result set with no duplicate Name and Address (but an autoID field is added, which can be omitted in the select clause when writing)