SQLSREVER如何創建和使用動態游標

▲創建游標

CREATE PROCEDURE Usp_CreateCursor(@Select_Command varchar(8000),@Cursor_Return CURSOR VARYING OUTPUT) AS
/*存儲過程名稱：Usp_CreateCursor
功能描述： 根據指定的SELECT創建一個動態游標
參數描述： @Select_Command ---SELECT語句;@Cursor_Return ---要返回的游標變量
思路： 動態游標的關鍵是不知如何去構造它的SELECT語句，因為SELECT是個字符串表量，定義時不能直接用它，但它可以來源於表。
所以我的目的就是創建一個統一的表，從中取數據不就可以了。建表有一定的語法規則，所以就應該根據欄位列表生成相應的
格式，這個可以從系統表中獲取。關鍵的問題是如何將數據插入到臨時表，我摸索出一條語句可
實現這個功能，那就是INSERT INTO EXECUTE ，而SQL7.0的幫助未講。有表有數據就可以創建了。
創建人： 康劍民
創建日期： 2001-07-11
*/
Declare @Select_Command_Temp Varchar(8000), ---存放SELECT臨時語法
@Table_List varchar(255), ---存放表的列表
@Column_List varchar(8000),---存放欄位列表
@Table_Name varchar(30),---存放單獨表名
@Column_Name varchar(30),---存放單獨欄位名（但有可能是*）
@Column_Syntax varchar(8000),---存放欄位建表時的語法（綜合）
@Column_Name_Temp varchar(30),---存放欄位名稱
@Column_Type_Temp varchar(30),----存放欄位類型
@Column_Syntax_Temp varchar(8000),---存放欄位建表時的語法（單個）
@Column_Length_Temp int,---存放欄位長度
@Column_Xprec_Temp int,---存放欄位精度
@Column_Xscale_Temp int,---存放欄位小數位數
@From_Pos int,---存放from的位置
@Where_Pos int,---存放where的位置
@Having_Pos int,---存放having的位置
@Groupby_Pos int,---存放groupby的位置
@Orderby_Pos int,---存放orderby的位置
@Temp_Pos int,---臨時變量
@Column_Count int,---存放欄位總數
@Loop_Seq int---循環步進變量

---創建臨時表
Create Table #Test(a int)
---如果傳來的SELECT語句不是以'select'開頭，自動修改
If Left(Lower(Ltrim(@Select_Command)),6) <> 'select' Select @Select_Command = 'Select ' + @Select_Command
---將開頭‘SELECT’去掉
Select @Select_Command_Temp = Lower(Ltrim(@Select_Command))
If Left(@Select_Command_Temp,6) = 'select' Select @Select_Command_Temp = Right(@Select_Command_Temp,Len(@Select_Command_Temp) - 7)
---取各保留字位置，以便獲得表的列表
Select @From_Pos = CHARINDEX(' from ',@Select_Command_Temp)
Select @Where_Pos = CHARINDEX(' where ',@Select_Command_Temp)
Select @Having_Pos = CHARINDEX(' having ',

@Select_Command_Temp)
Select @Groupby_Pos = CHARINDEX(' groupby ',@Select_Command_Temp)
Select @Orderby_Pos = CHARINDEX(' orderby ',@Select_Command_Temp)

If @Where_Pos > 0 Select @Temp_Pos = @Where_Pos
If @Having_Pos > 0 And @Having_Pos < @Temp_Pos Select @Temp_Pos = @Having_Pos
If @Groupby_Pos > 0 And @Groupby_Pos < @Temp_Pos Select @Temp_Pos = @Groupby_Pos
If @Orderby_Pos > 0 And @Orderby_Pos < @Temp_Pos Select @Temp_Pos = @Orderby_Pos
---取表列表
If @Temp_Pos > 0
Begin
Select @Table_List = SUBSTRING(@Select_Command_Temp,@From_Pos + 6 ,@Temp_Pos - @From_Pos - 1)
End
Else
Beg

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Select @Table_List = SUBSTRING(@Select_Command_Temp,@From_Pos + 6 ,Len(@Select_Command_Temp) - @From_Pos - 1)
End

Select @Column_Syntax = '
---只列出欄位
Select @Select_Command_Temp = Left(@Select_Command_Temp,@From_Pos - 1)
While Len(@Select_Command_Temp) > 0
Begin
---取逗號位置
Select @Temp_Pos = CHARINDEX(',',@Select_Command_Temp)
---初次取欄位名稱
If @Temp_Pos > 0
Begin
Select @Column_Name = Left(@Select_Command_Temp,@Temp_Pos - 1)
End
Else
Begin
Select @Column_Name = @Select_Command_Temp
End
---取表名和欄位名（可能是‘*’）
If CHARINDEX('.',@Column_Name) > 0
Begin
Select @Table_Name = Left(@Column_Name,CHARINDEX('.',@Column_Name) - 1)
Select @Column_Name = Right(@Column_Name,Len(@Column_Name) - CHARINDEX('.',@Column_Name))
End
Else
Begin
Select @Table_Name = @Table_List
End

---欄位出現'*'
If CHARINDEX('*',@Column_Name) > 0
Begin
Select @Column_Name = '
Select @Loop_Seq = 1
---取欄位個數
Select @Column_Count = Count(*)
From SysColumns
Where Id = Object_Id(@Table_name)
While @Loop_Seq <= @Column_Count
Begin
---取欄位名稱,欄位類型，長度，精度，小數位
Select @Column_Name_Temp = SysColumns.Name,
@Column_Type_Temp = Lower(SysTypes.Name),
@Column_Length_Temp = SysColumns.Length,

@Column_Xprec_Temp = SysColumns.Xprec,
@Column_Xscale_Temp = SysColumns.Xscale
From SysColumns,SysTypes
Where SysColumns.Id = Object_Id(@Table_name) And
SysColumns.Colid = @Loop_Seq And
SysColumns.XuserType = SysTypes.XuserType
---形成欄位語法表達式
Select @Column_Syntax_Temp = Case When @Column_Type_Temp In ('datetime','image','int') Then @Column_Name_Temp + ' ' + @Column_Type_Temp
When @Column_Type_Temp In ('binary','bit','char','varchar') Then @Column_Name_Temp + ' ' + @Column_Type_Temp + '('+Convert(Varchar(10),@Column_Length_Temp) + ')'
&

您正在看的SQLserver教程是:SQLSREVER如何創建和使用動態游標。nbsp; Else @Column_Name_Temp + ' ' + @Column_Type_Temp + '('+Convert(varchar(10),@Column_Xprec_Temp) + ',' + Convert(varchar(10),@Column_Xscale_Temp) + ')'
End
Select @Column_Syntax = @Column_Syntax + @Column_Syntax_Temp + ','
Select @Loop_Seq = @loop_Seq + 1
End
End
Else
Begin
---取欄位名稱
Select @Column_Name_Temp = @Column_Name
---取欄位類型，長度，精度，小數位
Select @Column_Type_Temp = Lower(SysTypes.Name),
@Column_Length_Temp = Isnull(SysColumns.Length,0),
@Column_Xprec_Temp = Isnull(SysColumns.Xprec,0),
@Column_Xscale_Temp = Isnull(SysColumns.Xscale,0)
From SysColumns,SysTypes
Where SysColumns.Id = Object_Id(@Table_name) And
SysColumns.Name = @Column_Name_Temp And
SysColumns.XuserType = SysTypes.XuserType
---形成欄位語法表達式
Select @Column_Syntax_Temp = Case When @Column_Type_Temp In ('datetime','image','int') Then @Column_Name_Temp + ' ' + @Column_Type_Temp
When @Column_Type_Temp In ('binary','bit','char','varchar') Then @Column_Name_Temp + ' ' + @Column_Type_Temp + '('+Convert(Varchar(10),@Column_Length_Temp) + ')'
Else @Column_Name_Temp + ' ' + @Column_Type_Temp + '('+Convert(varchar(10),@Column_Xprec_Temp) + ',

' + Convert(varchar(10),@Column_Xscale_Temp) + ')'
End
Select @Column_Syntax = @Column_Syntax + @Column_Syntax_Temp + ','

End
---處理欄位列表
If @Temp_Pos > 0
Begin
Select @Select_Command_Temp = Right(@Select_Command_Temp,Len(@Select_Command_Temp) - @Temp_Pos)
End
Else
Begin
Select @Select_Command_Temp = '
 

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End
---形成正確的欄位創建語法
Select @Column_Syntax = Left(@Column_Syntax,Len(@Column_Syntax) - 1)
---修改臨時表的結構
Execute('Alter Table #Test Add '+@Column_Syntax)
Execute('Alter Table #Test Drop Column a')
---將SELECT執行的結構集插入到臨時表
Insert Into #Test
Execute(@Select_Command)
---創建游標
Set @Cursor_Return = CURSOR LOCAL SCROLL READ_ONLY FOR
Select *
From #Test
---打開游標
Open @Cursor_Return

▲使用游標

/注:在SELECT中有幾項,fetch from @cursor_name into @cust_id就應該聲明幾個變量,而且順序和類型必須一致.*/
declare @cursor_name cursor,
@select_command varchar(8000),
@cust_id varchar(20)
select @select_command = 'select cust_id from so_cust'
execute usp_createcursor @select_command,@cursor_name OUTPUT
fetch from @cursor_name into @cust_id
while @@fetch_status = 0
begin
fetch from @cursor_name into @cust_id
end
close @cursor_name
deallocate cursor_name

說明:上述代碼在MSS SQL Server7.0上通過。其它數據庫只需修改一下抓取欄位及其類型的系統表就可以了。