基於Mysql的通用分頁存儲過程

　　前面“結合JSTL用配置來完成基於存儲過程的分頁顯示”文章中使用的是SQL Server 2000數據庫，而由於Web開發可能不僅僅使用一種數據庫，比如還可能用到Mysql等，因此爲了在Mysql下方便的使用分頁，筆者將分頁存儲過程P_viewPage在Mysql下進行了改寫，通用性不變，功能也基本一樣，讀者可以按照自己的需求自行調用該存儲過程實現分頁，也可以按照前面文章中那個項目模板實現分頁顯示，這裏不得不爲自己贊一下，由於前面文章中介紹的項目模板移植性好，你除了某些必要的工作如在Mysql下重新構建數據庫，重寫分頁存儲過程和加載Mysql驅動外，僅僅針對項目的變化就是重寫連接池配置文件Proxool.xml，使其適應Mysql配置，而項目其它任何地方均勿需做改動，是不是特別方便。而且我們完全可以實現項目中兩種不同數據庫的無縫結合，同時訪問兩種不同的數據庫而不對項目做任何代碼的改寫，你要做的工作也僅僅是在連接池配置文件Proxool.xml中添加一個新的連接池而已！Perfect！下面看看我們在Mysql下重寫的分頁存儲過程P_viewPage.

CREATE PROCEDURE `P_viewPage`(  
       $TableName VARCHAR(200),  
       $FieldList VARCHAR(2000),  
       $PrimaryKey VARCHAR(100),  
       $Where VARCHAR(1000),  
       $Order VARCHAR(1000),  
       $SortType INT,  
       $RecorderCount INT,  
       $PageSize INT,  
       $PageIndex INT,  
OUT    $TotalCount INTEGER,  
OUT    $TotalPageCount INTEGER  
)  
BEGIN  

IF !(($TableName is null OR $TableName='') OR ($FieldList is null OR $FieldList='') OR ($PrimaryKey is null OR $PrimaryKey='') OR $SortType < 1 OR $SortType >3 OR $RecorderCount < 0 OR $PageSize < 0 OR $PageIndex < 0) THEN  

IF ($where is null OR $where='') THEN  
  SET @new_where1 = ' ' ;  
  SET @new_where2 = ' WHERE ' ;  
ELSE  
  SET @new_where1 =concat(' WHERE ',$where);  
  SET @new_where2 =concat(' WHERE ',$where,' AND ');  
END IF;  

IF $order='' OR $SortType = 1 OR $SortType = 2 THEN  
  IF $SortType = 1 THEN  
       SET @new_order =concat(' ORDER BY ',$PrimaryKey,' ASC' );  
    END IF;  
  IF $SortType = 2 THEN  
       SET @new_order =concat(' ORDER BY ',$PrimaryKey,' DESC');  
    END IF;  
ELSE  
  SET @new_order =concat(' ORDER BY ',$Order);  
END IF;  

SET @SqlCount = concat('SELECT COUNT(*) into @TotalCount FROM ',$TableName,@new_where1);  
SET @SqlCount1 = concat('SELECT CEILING((COUNT(*)+0.0)/',$PageSize,') into @TotalPageCount FROM ',$TableName,@new_where1);  
IF $RecorderCount = 0 THEN  
     PREPARE stmt1 FROM @SqlCount;  
     EXECUTE stmt1;  
     set $TotalCount=@TotalCount;  
     PREPARE stmt1 FROM @SqlCount1;  
     EXECUTE stmt1;  
     set $TotalPageCount=@TotalPageCount;  
ELSE  
  set $TotalCount = $RecorderCount;  
END IF;  

IF $PageIndex > CEILING(($TotalCount+0.0)/$PageSize) THEN  
  SET $PageIndex = CEILING(($TotalCount+0.0)/$PageSize);  
END IF;  

IF $PageIndex = 0 or $PageIndex = 1 THEN  
   SET @Sql=concat('SELECT ',$FieldList,' FROM ',$TableName,@new_where1,@new_order,' limit ',$PageSize);  
ELSE  
  IF $SortType = 1 THEN  
       SET @Sql=concat('SELECT ',$FieldList,' FROM ',$TableName,@new_where2,$PrimaryKey,' > (SELECT max(',$PrimaryKey,') FROM (SELECT ',$PrimaryKey,' FROM ',$TableName,@new_where1,@new_order,' limit ',$PageSize*($PageIndex-1),' ) AS TMP) ',@new_order,' limit ',$PageSize);  
  END IF;  
  IF $SortType = 2 THEN  
       SET @Sql=concat('SELECT ',$FieldList,' FROM ',$TableName,@new_where2,$PrimaryKey,' < (SELECT MIN(',$PrimaryKey,') FROM (SELECT ',$PrimaryKey,' FROM ',$TableName,@new_where1,@new_order,' limit ',$PageSize*($PageIndex-1),' ) AS TMP) ',@new_order,' limit ',$PageSize);  
    END IF;  
  IF $SortType = 3 THEN  
      IF INSTR($Order,',') > 0 THEN  
            SET @Sql=concat('SELECT ',$FieldList,' FROM ',$TableName,@new_where2,$PrimaryKey,' NOT IN (SELECT ',$PrimaryKey,' FROM (SELECT ',$PrimaryKey,' FROM ',$TableName,@new_where1,@new_order,' limit ',$PageSize*($PageIndex-1),' ) a)',@new_order,' limit ',$PageSize);  
      ELSE  
            SET @new_order =concat(' ORDER BY ',$PrimaryKey,' ASC' );  
            SET @Sql=concat('SELECT ',$FieldList,' FROM ',$TableName,@new_where2,$PrimaryKey,' > (SELECT max(',$PrimaryKey,') FROM (SELECT ',$PrimaryKey,' FROM ',$TableName,@new_where1,@new_order,' limit ',$PageSize*($PageIndex-1),' ) AS TMP) ',@new_order,' limit ',$PageSize);  
      END IF;  
  END IF;  
END IF;  

Prepare stmt2 from @Sql;  
execute stmt2;  

END IF;  
END ;

 

Job Done！