这两天帮朋友修改一个项目,看到一个存储过程,感觉性能非常高。于是,整合自己以前搜集的比较好的存储过程,拿来跟大家分享下
(下面的代码原来我想用折叠的代码的,但是在google里面老是添加不了折叠的代码,所以就整屏的贴出来了,望大家不要见外。)朋友的比较好的存储过程。优点是:性能非常的高,每次查询都是根据ID查询,每次都是对一半的数据进行分页。缺点是:当有多个排序条件时,分页数据显示会出现问题。(该问题在第二个网友的分页存储过程中有解决的方法)。
代码如下:
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
ALTER PROCEDURE [dbo].[proc_page]
(
@tblName nvarchar(200), ----要显示的表或多个表的连接lihu
@fldName nvarchar(500) = '*', ----要显示的字段列表
@pageSize int = 10, ----每页显示的记录个数
@page int = 1, ----要显示那一页的记录
@fldSort nvarchar(200) = null, ----排序字段列表或条件
@Sort bit = 0, ----排序方法,0为升序,1为降序(如果是多字段排列Sort指代最后一个排序字段的排列顺序(最后一个排序字段不加排序标记)--程序传参如:' SortA Asc,SortB Desc,SortC ')
@strCondition nvarchar(1000), ----查询条件,不需where
@ID nvarchar(150), ----主表的主键
@Dist bit = 0, ----是否添加查询字段的 DISTINCT 默认0不添加/1添加
@pageCount int = 1 output, ----查询结果分页后的总页数
@Counts int = 1 output ----查询到的记录数
)
AS
SET NOCOUNT ON
Declare @sqlTmp nvarchar(1000) ----存放动态生成的SQL语句
Declare @strTmp nvarchar(1000) ----存放取得查询结果总数的查询语句
Declare @strID nvarchar(1000) ----存放取得查询开头或结尾ID的查询语句
Declare @strSortType nvarchar(10) ----数据排序规则A
Declare @strFSortType nvarchar(10) ----数据排序规则B
Declare @SqlSelect nvarchar(50) ----对含有DISTINCT的查询进行SQL构造
Declare @SqlCounts nvarchar(50) ----对含有DISTINCT的总数查询进行SQL构造
declare @timediff datetime --耗时测试时间差
select @timediff=getdate()
if @Dist = 0
begin
set @SqlSelect = 'select '
set @SqlCounts = 'Count(*)'
end
else
begin
set @SqlSelect = 'select distinct '
set @SqlCounts = 'Count(DISTINCT '+@ID+')'
end
if @Sort=0
begin
set @strFSortType=' ASC '
set @strSortType=' DESC '
end
else
begin
set @strFSortType=' DESC '
set @strSortType=' ASC '
end
--------生成查询语句--------
--此处@strTmp为取得查询结果数量的语句
if @strCondition is null or @strCondition='' --没有设置显示条件
begin
set @sqlTmp = @fldName + ' From ' + @tblName
set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName
set @strID = ' From ' + @tblName
end
else
begin
set @sqlTmp = + @fldName + 'From ' + @tblName + ' where (1>0) ' + @strCondition
set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName + ' where (1>0) ' + @strCondition
set @strID = ' From ' + @tblName + ' where (1>0) ' + @strCondition
end
----取得查询结果总数量-----
exec sp_executesql @strTmp,N'@Counts int out ',@Counts out
declare @tmpCounts int
if @Counts = 0
set @tmpCounts = 1
else
set @tmpCounts = @Counts
--取得分页总数
set @pageCount=(@tmpCounts+@pageSize-1)/@pageSize
/**当前页大于总页数 取最后一页**/
if 2>@pageCount
set 2=@pageCount
--/*-----数据分页2分处理-------*/
declare @pageIndex int --总数/页大小
declare @lastcount int --总数%页大小
set @pageIndex = @tmpCounts/@pageSize
set @lastcount = @tmpCounts%@pageSize
if @lastcount > 0
set @pageIndex = @pageIndex + 1
else
set @lastcount = @pagesize
--//***显示分页
if @strCondition is null or @strCondition='' --没有设置显示条件
begin
if @pageIndexbegin
if 2=1
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' order by '+ @fldSort +' '+ @strFSortType
else
begin
if @Sort=1
begin
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
+' order by '+ @fldSort +' '+ @strFSortType
end
else
begin
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(2-1) as Varchar(20)) +' '+ @ID +' from '+@tblName
+' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
+' order by '+ @fldSort +' '+ @strFSortType
end
end
end
else
begin
set 2= @pageIndex-2+1 --后半部分数据处理
if 2set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
else
if @Sort=1
begin
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(2-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName
+' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
end
else
begin
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
end
end
end
else --有查询条件
begin
if @pageIndexbegin
if @page=1
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where 1=1 ' + @strCondition + ' order by '+ @fldSort +' '+ @strFSortType
else if(@Sort=1)
begin
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' +' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
+' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType
end
else
begin
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName
+' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
+' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType
end
end
else
begin
set 2= @pageIndex-2+1 --后半部分数据处理
if 2set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
else if(@Sort=1)
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName
+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
+' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
else
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
+' where '+@ID+' +' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
+' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
end
end
------返回查询结果-----
exec sp_executesql @strTmp
select datediff(ms,@timediff,getdate()) as 耗时
print @strTmp
SET NOCOUNT OFF
网上的比较经典的存储过程
代码如下:
Create PROC P_viewPage
/**//*
nzperfect [no_mIss] 高效通用分页存储过程(双向检索) 2007.5.7 QQ:34813284
敬告:适用于单一主键或存在唯一值列的表或视图
ps:Sql语句为8000字节,调用时请注意传入参数及sql总长度不要超过指定范围
*/
@TableName VARCHAR(200), --表名
@FieldList VARCHAR(2000), --显示列名,如果是全部字段则为*
@PrimaryKey VARCHAR(100), --单一主键或唯一值键
@Where VARCHAR(2000), --查询条件 不含'where'字符,如id>10 and len(userid)>9
@Order VARCHAR(1000), --排序 不含'order by'字符,如id asc,userid desc,必须指定asc或desc
--注意当@SortType=3时生效,记住一定要在最后加上主键,否则会让你比较郁闷
@SortType INT, --排序规则 1:正序asc 2:倒序desc 3:多列排序方法
@RecorderCount INT, --记录总数 0:会返回总记录
@PageSize INT, --每页输出的记录数
@PageIndex INT, --当前页数
@TotalCount INT OUTPUT , --记返回总记录
@TotalPageCount INT OUTPUT --返回总页数
AS
SET NOCOUNT ON
IF ISNULL(@TotalCount,'') = '' SET @TotalCount = 0
SET @Order = RTRIM(LTRIM(@Order))
SET @PrimaryKey = RTRIM(LTRIM(@PrimaryKey))
SET @FieldList = REPLACE(RTRIM(LTRIM(@FieldList)),' ','')
WHILE CHARINDEX(', ',@Order) > 0 or CHARINDEX(' ,',@Order) > 0
BEGIN
SET @Order = REPLACE(@Order,', ',',')
SET @Order = REPLACE(@Order,' ,',',')
END
IF ISNULL(@TableName,'') = '' or ISNULL(@FieldList,'') = ''
or ISNULL(@PrimaryKey,'') = ''
or @SortType 3
or @RecorderCount BEGIN
PRINT('ERR_00')
RETURN
END
IF @SortType = 3
BEGIN
IF (UPPER(RIGHT(@Order,4))!=' ASC' AND UPPER(RIGHT(@Order,5))!=' DESC')
BEGIN PRINT('ERR_02') RETURN END
END
DECLARE @new_where1 VARCHAR(1000)
DECLARE @new_where2 VARCHAR(1000)
DECLARE @new_order1 VARCHAR(1000)
DECLARE @new_order2 VARCHAR(1000)
DECLARE @new_order3 VARCHAR(1000)
DECLARE @Sql VARCHAR(8000)
DECLARE @SqlCount NVARCHAR(4000)
IF ISNULL(@where,'') = ''
BEGIN
SET @new_where1 = ' '
SET @new_where2 = ' Where '
END
ELSE
BEGIN
SET @new_where1 = ' Where ' + @where
SET @new_where2 = ' Where ' + @where + ' AND '
END
IF ISNULL(@order,'') = '' or @SortType = 1 or @SortType = 2
BEGIN
IF @SortType = 1
BEGIN
SET @new_order1 = ' orDER BY ' + @PrimaryKey + ' ASC'
SET @new_order2 = ' orDER BY ' + @PrimaryKey + ' DESC'
END
IF @SortType = 2
BEGIN
SET @new_order1 = ' orDER BY ' + @PrimaryKey + ' DESC'
SET @new_order2 = ' orDER BY ' + @PrimaryKey + ' ASC'
END
END
ELSE
BEGIN
SET @new_order1 = ' orDER BY ' + @Order
END
IF @SortType = 3 AND CHARINDEX(','+@PrimaryKey+' ',','+@Order)>0
BEGIN
SET @new_order1 = ' orDER BY ' + @Order
SET @new_order2 = @Order + ','
SET @new_order2 = REPLACE(REPLACE(@new_order2,'ASC,','{ASC},'),'DESC,','{DESC},')
SET @new_order2 = REPLACE(REPLACE(@new_order2,'{ASC},','DESC,'),'{DESC},','ASC,')
SET @new_order2 = ' orDER BY ' + SUBSTRING(@new_order2,1,LEN(@new_order2)-1)
IF @FieldList '*'
BEGIN
SET @new_order3 = REPLACE(REPLACE(@Order + ',','ASC,',','),'DESC,',',')
SET @FieldList = ',' + @FieldList
WHILE CHARINDEX(',',@new_order3)>0
BEGIN
IF CHARINDEX(SUBSTRING(','+@new_order3,1,CHARINDEX(',',@new_order3)),','+@FieldList+',')>0
BEGIN
SET @FieldList =
@FieldList + ',' + SUBSTRING(@new_order3,1,CHARINDEX(',',@new_order3))
END
SET @new_order3 =
SUBSTRING(@new_order3,CHARINDEX(',',@new_order3)+1,LEN(@new_order3))
END
SET @FieldList = SUBSTRING(@FieldList,2,LEN(@FieldList))
END
END
SET @SqlCount = 'Select @TotalCount=COUNT(*),@TotalPageCount=CEILING((COUNT(*)+0.0)/'
+ CAST(@PageSize AS VARCHAR)+') FROM (Select * FROM ' + @TableName + @new_where1+') AS T'
IF @RecorderCount = 0
BEGIN
EXEC SP_EXECUTESQL @SqlCount,N'@TotalCount INT OUTPUT,@TotalPageCount INT OUTPUT',
@TotalCount OUTPUT,@TotalPageCount OUTPUT
END
ELSE
BEGIN
Select @TotalCount = @RecorderCount
END
IF @PageIndex > CEILING((@TotalCount+0.0)/@PageSize)
BEGIN
SET @PageIndex = CEILING((@TotalCount+0.0)/@PageSize)
END
IF @PageIndex = 1 or @PageIndex >= CEILING((@TotalCount+0.0)/@PageSize)
BEGIN
IF @PageIndex = 1 --返回第一页数据
BEGIN
SET @Sql = 'Select * FROM (Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM '
+ @TableName + @new_where1 + @new_order1 +') AS TMP ' + @new_order1
END
IF @PageIndex >= CEILING((@TotalCount+0.0)/@PageSize) --返回最后一页数据
BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ('
+ 'Select TOP ' + STR(ABS(@PageSize*@PageIndex-@TotalCount-@PageSize))
+ ' ' + @FieldList + ' FROM '
+ @TableName + @new_where1 + @new_order2 + ' ) AS TMP '
+ @new_order1
END
END
ELSE
BEGIN
IF @SortType = 1 --仅主键正序排序
BEGIN
IF @PageIndex BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM '
+ @TableName + @new_where2 + @PrimaryKey + ' > '
+ '(Select MAX(' + @PrimaryKey + ') FROM (Select TOP '
+ STR(@PageSize*(@PageIndex-1)) + ' ' + @PrimaryKey
+ ' FROM ' + @TableName
+ @new_where1 + @new_order1 +' ) AS TMP) '+ @new_order1
END
ELSE --反向检索
BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ('
+ 'Select TOP ' + STR(@PageSize) + ' '
+ @FieldList + ' FROM '
+ @TableName + @new_where2 + @PrimaryKey + ' + '(Select MIN(' + @PrimaryKey + ') FROM (Select TOP '
+ STR(@TotalCount-@PageSize*@PageIndex) + ' ' + @PrimaryKey
+ ' FROM ' + @TableName
+ @new_where1 + @new_order2 +' ) AS TMP) '+ @new_order2
+ ' ) AS TMP ' + @new_order1
END
END
IF @SortType = 2 --仅主键反序排序
BEGIN
IF @PageIndex BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM '
+ @TableName + @new_where2 + @PrimaryKey + ' + '(Select MIN(' + @PrimaryKey + ') FROM (Select TOP '
+ STR(@PageSize*(@PageIndex-1)) + ' ' + @PrimaryKey
+' FROM '+ @TableName
+ @new_where1 + @new_order1 + ') AS TMP) '+ @new_order1
END
ELSE --反向检索
BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ('
+ 'Select TOP ' + STR(@PageSize) + ' '
+ @FieldList + ' FROM '
+ @TableName + @new_where2 + @PrimaryKey + ' > '
+ '(Select MAX(' + @PrimaryKey + ') FROM (Select TOP '
+ STR(@TotalCount-@PageSize*@PageIndex) + ' ' + @PrimaryKey
+ ' FROM ' + @TableName
+ @new_where1 + @new_order2 +' ) AS TMP) '+ @new_order2
+ ' ) AS TMP ' + @new_order1
END
END
IF @SortType = 3 --多列排序,必须包含主键,且放置最后,否则不处理
BEGIN
IF CHARINDEX(',' + @PrimaryKey + ' ',',' + @Order) = 0
BEGIN PRINT('ERR_02') RETURN END
IF @PageIndex BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ( '
+ 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ( '
+ ' Select TOP ' + STR(@PageSize*@PageIndex) + ' ' + @FieldList
+ ' FROM ' + @TableName + @new_where1 + @new_order1 + ' ) AS TMP '
+ @new_order2 + ' ) AS TMP ' + @new_order1
END
ELSE --反向检索
BEGIN
SET @Sql = 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ( '
+ 'Select TOP ' + STR(@PageSize) + ' ' + @FieldList + ' FROM ( '
+ ' Select TOP ' + STR(@TotalCount-@PageSize *@PageIndex+@PageSize) + ' ' + @FieldList
+ ' FROM ' + @TableName + @new_where1 + @new_order2 + ' ) AS TMP '
+ @new_order1 + ' ) AS TMP ' + @new_order1
END
END
END
PRINT(@SQL)
EXEC(@Sql)
公司的存储过程,虽然效率不是太高,不过还行。
代码如下:
USE [CaiLi]
GO
/****** Object: StoredProcedure [dbo].[SqlPagination] Script Date: 10/26/2011 11:40:46 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE [dbo].[SqlPagination]
/*
***************************************************************
** 千万数量级分页存储过程 **
***************************************************************
参数说明:
1.Tables :表名称,视图
2.PrimaryKey :主关键字
3.Sort :排序语句,不带Order By 比如:NewsID Desc,OrderRows Asc
4.CurrentPage :当前页码
5.PageSize :分页尺寸
6.Filter :过滤语句,不带Where
7.Group :Group语句,不带Group By
***************************************************************/
(
@Tables varchar(1000),
@PrimaryKey varchar(100),
@Sort varchar(200) = NULL,
@CurrentPage int = 1,
@PageSize int = 10,
@Fields varchar(1000) = '*',
@Filter varchar(1000) = NULL,
@Group varchar(1000) = NULL
)
AS
/*默认排序*/
if @PrimaryKey IS NULL or @PrimaryKey = ''
set @PrimaryKey='ID'
IF @Sort IS NULL or @Sort = ''
SET @Sort = @PrimaryKey
IF @Fields IS NULL or @Fields = ''
SET @Fields = '*'
DECLARE @SortTable varchar(100)
DECLARE @SortName varchar(100)
DECLARE @strSortColumn varchar(200)
DECLARE @operator char(2)
DECLARE @type varchar(100)
DECLARE @prec int
/*设定排序语句.*/
if charindex(',',@Sort) >0
set @strSortColumn = substring(@Sort,0,charindex(',',@Sort))
else
set @strSortColumn = @Sort
IF CHARINDEX('DESC',@Sort)>0
BEGIN
SET @strSortColumn = REPLACE(@strSortColumn, 'DESC', '')
SET @operator = 'END
ELSE
BEGIN
IF CHARINDEX('ASC',@Sort)> 0
BEGIN
SET @strSortColumn = REPLACE(@strSortColumn, 'ASC', '')
SET @operator = '>='
END
END
IF CHARINDEX('.', @strSortColumn) > 0
BEGIN
SET @SortTable = SUBSTRING(@strSortColumn, 0, CHARINDEX('.',@strSortColumn))
SET @SortName = SUBSTRING(@strSortColumn, CHARINDEX('.',@strSortColumn) + 1, LEN(@strSortColumn))
END
ELSE
BEGIN
SET @SortTable = @Tables
SET @SortName = @strSortColumn
END
Select @type=t.name, @prec=c.prec
FROM sysobjects o
JOIN syscolumns c on o.id=c.id
JOIN systypes t on c.xusertype=t.xusertype
Where o.name = @SortTable AND c.name = @SortName
IF CHARINDEX('char', @type) > 0
SET @type = @type + '(' + CAST(@prec AS varchar) + ')'
DECLARE @strPageSize varchar(50)
DECLARE @strStartRow varchar(50)
DECLARE @strFilter varchar(1000)
DECLARE @strSimpleFilter varchar(1000)
DECLARE @strGroup varchar(1000)
DECLARE @strSort varchar(200)
/*默认当前页*/
IF @CurrentPage SET @CurrentPage = 1
/*设置分页参数.*/
SET @strPageSize = CAST(@PageSize AS varchar(50))
SET @strStartRow = CAST(((@CurrentPage - 1)*@PageSize + 1) AS varchar(50))
/*筛选以及分组语句.*/
IF @Filter IS NOT NULL AND @Filter != ''
BEGIN
SET @strFilter = ' Where 1=1 ' + @Filter + ' '
SET @strSimpleFilter =@Filter + ' '
END
ELSE
BEGIN
SET @strSimpleFilter = ''
SET @strFilter = ''
END
IF @Group IS NOT NULL AND @Group != ''
SET @strGroup = ' GROUP BY ' + @Group + ' '
ELSE
SET @strGroup = ''
IF @Sort IS NOT NULL AND @Sort != ''
SET @strSort = ' ORDER BY ' + @Sort + ' '
ELSE
SET @strSort = ''
--print('Select ' + @Fields + ' FROM ' + '(Select *,ROW_NUMBER() OVER ('+@strSort+')as RowNumber FROM '+@Tables+') t' + ' Where t.RowNumber between '+@strStartRow+' and '+' ' + @strSimpleFilter + ' ' + @strSort + @strGroup)
/*执行查询语句*/
declare @STRORDER varchar(50)
if CHARINDEX(',',@strSort)>0
set @STRORDER=SUBSTRING(@strSort, 0, CHARINDEX(',',@strSort))
else
set @STRORDER=@strSort
EXEC(
' DECLARE @SortColumn ' + @type + '
DECLARE @TotalCount int
DECLARE @ENDCOUNT int
DECLARE @strENDCOUNT varchar(50)
--Select count(1) FROM ' + @Tables + @strFilter+'
set @TotalCount=(Select count(1) FROM ' + @Tables + @strFilter+')'+'
SET ROWCOUNT ' + @strStartRow + '
SET @ENDCOUNT=CAST('+@strStartRow+' AS int)+CAST('+@strPageSize+' AS int)-1
IF @ENDCOUNT > @TotalCount
BEGIN
SET @ENDCOUNT = @TotalCount
END
set @strENDCOUNT=CAST(@ENDCOUNT AS varchar(50))
Select @SortColumn=' + @strSortColumn + ' FROM ' + @Tables + @strFilter + ' ' + @strGroup + @strSort + '
SET ROWCOUNT ' + @strPageSize + '
Select ' + @Fields + ' FROM ' + '(Select *,ROW_NUMBER() OVER ('+@STRORDER+')as RowNumber FROM '+@Tables+' where 1=1 '+@strSimpleFilter+') t' + ' Where t.RowNumber between '+@strStartRow+' and @strENDCOUNT ' + @strGroup + @strSort + ' ')
GO

InnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.

Key metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.

Usingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB

MySQL/InnoDB supports four transaction isolation levels: ReadUncommitted, ReadCommitted, RepeatableRead and Serializable. 1.ReadUncommitted allows reading of uncommitted data, which may cause dirty reading. 2. ReadCommitted avoids dirty reading, but non-repeatable reading may occur. 3.RepeatableRead is the default level, avoiding dirty reading and non-repeatable reading, but phantom reading may occur. 4. Serializable avoids all concurrency problems but reduces concurrency. Choosing the appropriate isolation level requires balancing data consistency and performance requirements.

MySQL is suitable for web applications and content management systems and is popular for its open source, high performance and ease of use. 1) Compared with PostgreSQL, MySQL performs better in simple queries and high concurrent read operations. 2) Compared with Oracle, MySQL is more popular among small and medium-sized enterprises because of its open source and low cost. 3) Compared with Microsoft SQL Server, MySQL is more suitable for cross-platform applications. 4) Unlike MongoDB, MySQL is more suitable for structured data and transaction processing.

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 English version
Recommended: Win version, supports code prompts!

SublimeText3 Mac version
God-level code editing software (SublimeText3)