SQL Server性能常用语句

1. 查看各表的数据行数
   

   SELECT
   o.name, i. ROWS
   FROM sysobjects o, sysindexes i
   WHERE o.id = i.id  AND o.Xtype = 'U' AND i.indid < 2
   ORDER BY o.name;

2. 计算数据库中各个表每行记录所占用空间
   

   --SELECT * FROM Employees AS e;
   
   CREATE TABLE #tablespaceinfo
       (
         nameinfo VARCHAR(50) ,
         rowsinfo BIGINT ,
         reserved VARCHAR(20) ,
         datainfo VARCHAR(20) ,
         index_size VARCHAR(20) ,
         unused VARCHAR(20)
       )  
    
   DECLARE @tablename VARCHAR(255);  
    
   DECLARE Info_cursor CURSOR
   FOR
       SELECT  '[' + [name] + ']'
       FROM    sys.tables
       WHERE   type = 'U';  
    
   OPEN Info_cursor  
   FETCH NEXT FROM Info_cursor INTO @tablename  
    
   WHILE @@FETCH_STATUS = 0
       BEGIN 
           INSERT  INTO #tablespaceinfo
                   EXEC sp_spaceused @tablename  
           FETCH NEXT FROM Info_cursor  
       INTO @tablename  
       END 
    
   CLOSE Info_cursor  
   DEALLOCATE Info_cursor  
    
   --创建临时表
   CREATE TABLE [#tmptb]
       (
         TableName VARCHAR(50) ,
         DataInfo BIGINT ,
         RowsInfo BIGINT ,
         Spaceperrow  AS ( CASE RowsInfo
                            WHEN 0 THEN 0
                            ELSE CAST(DataInfo AS decimal(18,2))/CAST(RowsInfo AS decimal(18,2))
                          END ) PERSISTED
       )
   
   --插入数据到临时表
   INSERT  INTO [#tmptb]
           ( [TableName] ,
             [DataInfo] ,
             [RowsInfo]
           )
           SELECT  [nameinfo] ,
                   CAST(REPLACE([datainfo], 'KB', '') AS BIGINT) AS 'datainfo' ,
                   [rowsinfo]
           FROM    #tablespaceinfo
           ORDER BY CAST(REPLACE(reserved, 'KB', '') AS INT) DESC  
   
   
   --汇总记录
   SELECT  [tbspinfo].* ,
           [tmptb].[Spaceperrow] AS '每行记录大概占用空间（KB）'
   FROM    [#tablespaceinfo] AS tbspinfo ,
           [#tmptb] AS tmptb
   WHERE   [tbspinfo].[nameinfo] = [tmptb].[TableName]
   ORDER BY CAST(REPLACE([tbspinfo].[reserved], 'KB', '') AS INT) DESC  
   
   DROP TABLE [#tablespaceinfo]
   DROP TABLE [#tmptb]

3. 获取SQL语句执行时

　　　　

DECLARE @a DATETIME
DECLARE @b DATETIME
SELECT @a=GETDATE()
exec sp_tables;        --查看表
SELECT @b=GETDATE()
SELECT @b-@a