SQL code

SQL code

  

   
   --
   处理表重复记录(查询和删除)
    /*
   ***************************************************************************************************************************************************** 1、Num、Name相同的重复值记录,没有大小关系只保留一条 2、Name相同,ID有大小关系时,保留大或小其中一个记录 整理人：中国风(Roy) 日期:2008.06.06 *****************************************************************************************************************************************************
   */
    
   --
   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)
    
    
   --
   > --> (Roy)生成測試數據
    
    
   if
    
   not
    
   object_id
   (
   '
   Tempdb..#T
   '
   ) 
   is
    
   null
    
   drop
    
   table
    #T 
   Go
    
   Create
    
   table
    #T(
   [
   ID
   ]
    
   int
   ,
   [
   Name
   ]
    
   nvarchar
   (
   1
   ),
   [
   Memo
   ]
    
   nvarchar
   (
   2
   )) 
   Insert
    #T 
   select
    
   1
   ,N
   '
   A
   '
   ,N
   '
   A1
   '
    
   union
    
   all
    
   select
    
   2
   ,N
   '
   A
   '
   ,N
   '
   A2
   '
    
   union
    
   all
    
   select
    
   3
   ,N
   '
   A
   '
   ,N
   '
   A3
   '
    
   union
    
   all
    
   select
    
   4
   ,N
   '
   B
   '
   ,N
   '
   B1
   '
    
   union
    
   all
    
   select
    
   5
   ,N
   '
   B
   '
   ,N
   '
   B2
   '
    
   Go
    
   --
   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
    
   方法1: 
   Select
    
   *
    
   from
    #T a 
   where
    
   not
    
   exists
   (
   select
    
   1
    
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   <
   a.ID) 方法2: 
   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 方法3: 
   select
    
   *
    
   from
    #T a 
   where
    ID
   =
   (
   select
    
   min
   (ID) 
   from
    #T 
   where
    Name
   =
   a.Name) 方法4: 
   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
    方法5: 
   select
    
   *
    
   from
    #T a 
   group
    
   by
    ID,Name,Memo 
   having
    ID
   =
   (
   select
    
   min
   (ID)
   from
    #T 
   where
    Name
   =
   a.Name) 方法6: 
   select
    
   *
    
   from
    #T a 
   where
    (
   select
    
   count
   (
   1
   ) 
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   <
   a.ID)
   =
   0
    方法7: 
   select
    
   *
    
   from
    #T a 
   where
    ID
   =
   (
   select
    
   top
    
   1
    ID 
   from
    #T 
   where
    Name
   =
   a.name 
   order
    
   by
    ID) 方法8: 
   select
    
   *
    
   from
    #T a 
   where
    ID
   !>all
   (
   select
    ID 
   from
    #T 
   where
    Name
   =
   a.Name) 方法9(注:ID为唯一时可用): 
   select
    
   *
    
   from
    #T a 
   where
    ID 
   in
   (
   select
    
   min
   (ID) 
   from
    #T 
   group
    
   by
    Name) 
   --
   SQL2005:
    
    方法10: 
   select
    ID,Name,Memo 
   from
    (
   select
    
   *
   ,
   min
   (ID)
   over
   (partition 
   by
    Name) 
   as
    MinID 
   from
    #T a)T 
   where
    ID
   =
   MinID 方法11: 
   select
    ID,Name,Memo 
   from
    (
   select
    
   *
   ,row_number()
   over
   (partition 
   by
    Name 
   order
    
   by
    ID) 
   as
    MinID 
   from
    #T a)T 
   where
    MinID
   =
   1
    生成结果: 
   /*
    ID Name Memo ----------- ---- ---- 1 A A1 4 B B1 (2 行受影响) 
   */
    
   --
   II、Name相同ID最大的记录,与min相反:
    
   方法1: 
   Select
    
   *
    
   from
    #T a 
   where
    
   not
    
   exists
   (
   select
    
   1
    
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   >
   a.ID) 方法2: 
   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 方法3: 
   select
    
   *
    
   from
    #T a 
   where
    ID
   =
   (
   select
    
   max
   (ID) 
   from
    #T 
   where
    Name
   =
   a.Name) 
   order
    
   by
    ID 方法4: 
   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
    方法5: 
   select
    
   *
    
   from
    #T a 
   group
    
   by
    ID,Name,Memo 
   having
    ID
   =
   (
   select
    
   max
   (ID)
   from
    #T 
   where
    Name
   =
   a.Name) 方法6: 
   select
    
   *
    
   from
    #T a 
   where
    (
   select
    
   count
   (
   1
   ) 
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   >
   a.ID)
   =
   0
    方法7: 
   select
    
   *
    
   from
    #T a 
   where
    ID
   =
   (
   select
    
   top
    
   1
    ID 
   from
    #T 
   where
    Name
   =
   a.name 
   order
    
   by
    ID 
   desc
   ) 方法8: 
   select
    
   *
    
   from
    #T a 
   where
    ID
   !<all
   (
   select
    ID 
   from
    #T 
   where
    Name
   =
   a.Name) 方法9(注:ID为唯一时可用): 
   select
    
   *
    
   from
    #T a 
   where
    ID 
   in
   (
   select
    
   max
   (ID) 
   from
    #T 
   group
    
   by
    Name) 
   --
   SQL2005:
    
    方法10: 
   select
    ID,Name,Memo 
   from
    (
   select
    
   *
   ,
   max
   (ID)
   over
   (partition 
   by
    Name) 
   as
    MinID 
   from
    #T a)T 
   where
    ID
   =
   MinID 方法11: 
   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
    生成结果2: 
   /*
    ID Name Memo ----------- ---- ---- 3 A A3 5 B B2 (2 行受影响) 
   */
    
   --
   2、删除重复记录有大小关系时,保留大或小其中一个记录
    
    
   --
   > --> (Roy)生成測試數據
    
    
   if
    
   not
    
   object_id
   (
   '
   Tempdb..#T
   '
   ) 
   is
    
   null
    
   drop
    
   table
    #T 
   Go
    
   Create
    
   table
    #T(
   [
   ID
   ]
    
   int
   ,
   [
   Name
   ]
    
   nvarchar
   (
   1
   ),
   [
   Memo
   ]
    
   nvarchar
   (
   2
   )) 
   Insert
    #T 
   select
    
   1
   ,N
   '
   A
   '
   ,N
   '
   A1
   '
    
   union
    
   all
    
   select
    
   2
   ,N
   '
   A
   '
   ,N
   '
   A2
   '
    
   union
    
   all
    
   select
    
   3
   ,N
   '
   A
   '
   ,N
   '
   A3
   '
    
   union
    
   all
    
   select
    
   4
   ,N
   '
   B
   '
   ,N
   '
   B1
   '
    
   union
    
   all
    
   select
    
   5
   ,N
   '
   B
   '
   ,N
   '
   B2
   '
    
   Go
    
   --
   I、Name相同ID最小的记录(推荐用1,2,3),保留最小一条
    
   方法1: 
   delete
    a 
   from
    #T a 
   where
    
   exists
   (
   select
    
   1
    
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   <
   a.ID) 方法2: 
   delete
    a 
   from
    #T a 
   left
    
   join
    (
   select
    
   min
   (ID)ID,Name 
   from
    #T 
   group
    
   by
    Name) b 
   on
    a.Name
   =
   b.Name 
   and
    a.ID
   =
   b.ID 
   where
    b.Id 
   is
    
   null
    方法3: 
   delete
    a 
   from
    #T a 
   where
    ID 
   not
    
   in
    (
   select
    
   min
   (ID) 
   from
    #T 
   where
    Name
   =
   a.Name) 方法4(注:ID为唯一时可用): 
   delete
    a 
   from
    #T a 
   where
    ID 
   not
    
   in
   (
   select
    
   min
   (ID)
   from
    #T 
   group
    
   by
    Name) 方法5: 
   delete
    a 
   from
    #T a 
   where
    (
   select
    
   count
   (
   1
   ) 
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   <
   a.ID)
   >
   0
    方法6: 
   delete
    a 
   from
    #T a 
   where
    ID
   <>
   (
   select
    
   top
    
   1
    ID 
   from
    #T 
   where
    Name
   =
   a.name 
   order
    
   by
    ID) 方法7: 
   delete
    a 
   from
    #T a 
   where
    ID
   >any
   (
   select
    ID 
   from
    #T 
   where
    Name
   =
   a.Name) 
   select
    
   *
    
   from
    #T 生成结果: 
   /*
    ID Name Memo ----------- ---- ---- 1 A A1 4 B B1 (2 行受影响) 
   */
    
   --
   II、Name相同ID保留最大的一条记录:
    
    方法1: 
   delete
    a 
   from
    #T a 
   where
    
   exists
   (
   select
    
   1
    
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   >
   a.ID) 方法2: 
   delete
    a 
   from
    #T a 
   left
    
   join
    (
   select
    
   max
   (ID)ID,Name 
   from
    #T 
   group
    
   by
    Name) b 
   on
    a.Name
   =
   b.Name 
   and
    a.ID
   =
   b.ID 
   where
    b.Id 
   is
    
   null
    方法3: 
   delete
    a 
   from
    #T a 
   where
    ID 
   not
    
   in
    (
   select
    
   max
   (ID) 
   from
    #T 
   where
    Name
   =
   a.Name) 方法4(注:ID为唯一时可用): 
   delete
    a 
   from
    #T a 
   where
    ID 
   not
    
   in
   (
   select
    
   max
   (ID)
   from
    #T 
   group
    
   by
    Name) 方法5: 
   delete
    a 
   from
    #T a 
   where
    (
   select
    
   count
   (
   1
   ) 
   from
    #T 
   where
    Name
   =
   a.Name 
   and
    ID
   >
   a.ID)
   >
   0
    方法6: 
   delete
    a 
   from
    #T a 
   where
    ID
   <>
   (
   select
    
   top
    
   1
    ID 
   from
    #T 
   where
    Name
   =
   a.name 
   order
    
   by
    ID 
   desc
   ) 方法7: 
   delete
    a 
   from
    #T a 
   where
    ID
   <any
   (
   select
    ID 
   from
    #T 
   where
    Name
   =
   a.Name) 
   select
    
   *
    
   from
    #T 
   /*
    ID Name Memo ----------- ---- ---- 3 A A3 5 B B2 (2 行受影响) 
   */
    
   --
   3、删除重复记录没有大小关系时，处理重复值
    
    
   --
   > --> (Roy)生成測試數據
    
    
   if
    
   not
    
   object_id
   (
   '
   Tempdb..#T
   '
   ) 
   is
    
   null
    
   drop
    
   table
    #T 
   Go
    
   Create
    
   table
    #T(
   [
   Num
   ]
    
   int
   ,
   [
   Name
   ]
    
   nvarchar
   (
   1
   )) 
   Insert
    #T 
   select
    
   1
   ,N
   '
   A
   '
    
   union
    
   all
    
   select
    
   1
   ,N
   '
   A
   '
    
   union
    
   all
    
   select
    
   1
   ,N
   '
   A
   '
    
   union
    
   all
    
   select
    
   2
   ,N
   '
   B
   '
    
   union
    
   all
    
   select
    
   2
   ,N
   '
   B
   '
    
   Go
    方法1: 
   if
    
   object_id
   (
   '
   Tempdb..#
   '
   ) 
   is
    
   not
    
   null
    
   drop
    
   table
    # 
   Select
    
   distinct
    
   *
    
   into
    # 
   from
    #T
   --
   排除重复记录结果集生成临时表#
    
    
   truncate
    
   table
    #T
   --
   清空表
    
    
   insert
    #T 
   select
    
   *
    
   from
    # 
   --
   把临时表#插入到表#T中
    
    
   --
   查看结果
    
   select
    
   *
    
   from
    #T 
   /*
    Num Name ----------- ---- 1 A 2 B (2 行受影响) 
   */
    
   --
   重新执行测试数据后用方法2
    
   方法2: 
   alter
    
   table
    #T 
   add
    ID 
   int
    
   identity
   --
   新增标识列
    
   go
    
   delete
    a 
   from
    #T a 
   where
    
   exists
   (
   select
    
   1
    
   from
    #T 
   where
    Num
   =
   a.Num 
   and
    Name
   =
   a.Name 
   and
    ID
   >
   a.ID)
   --
   只保留一条记录
    
   go
    
   alter
    
   table
    #T 
   drop
    
   column
    ID
   --
   删除标识列
    
    
   --
   查看结果
    
   select
    
   *
    
   from
    #T 
   /*
    Num Name ----------- ---- 1 A 2 B (2 行受影响) 
   */
    
   --
   重新执行测试数据后用方法3
    
   方法3: 
   declare
    Roy_Cursor 
   cursor
    local 
   for
    
   select
    
   count
   (
   1
   )
   -
   1
   ,Num,Name 
   from
    #T 
   group
    
   by
    Num,Name 
   having
    
   count
   (
   1
   )
   >
   1
    
   declare
    
   @con
    
   int
   ,
   @Num
    
   int
   ,
   @Name
    
   nvarchar
   (
   1
   ) 
   open
    Roy_Cursor 
   fetch
    
   next
    
   from
    Roy_Cursor 
   into
    
   @con
   ,
   @Num
   ,
   @Name
    
   while
    
   @@Fetch_status
   =
   0
    
   begin
    
   set
    
   rowcount
    
   @con
   ; 
   delete
    #T 
   where
    Num
   =
   @Num
    
   and
    Name
   =
   @Name
    
   set
    
   rowcount
    
   0
   ; 
   fetch
    
   next
    
   from
    Roy_Cursor 
   into
    
   @con
   ,
   @Num
   ,
   @Name
    
   end
    
   close
    Roy_Cursor 
   deallocate
    Roy_Cursor 
   --
   查看结果
    
   select
    
   *
    
   from
    #T 
   /*
    Num Name ----------- ---- 1 A 2 B (2 行受影响) 
   */