Copyright (c) 2007 Mike Chirico (email@example.com) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation. Last Updated: Fri Dec 21 12:37:14 EST 2007 TIP 1: Need to know how much fragmentation? DBCC SHOWCONTIG (tbl_transaction) There is also a more advanced option DBCC SHOWCONTIG (tbl_transaction) WITH TABLERESULTS, ALL_LEVELS There is also a defrag command DBCC INDEXDEFRAG(Northwind,Customers,1) TIP 2: This is a cool feature: IF object_id('OutputTest') IS NOT NULL BEGIN drop table OutputTest END CREATE TABLE OutputTest ( ID int NOT NULL, Description varchar(max) NOT NULL, ) INSERT INTO OutputTest (ID, Description) VALUES (1, 'row 1') INSERT INTO OutputTest (ID, Description) VALUES (2, 'row 2') INSERT INTO OutputTest (ID, Description) VALUES (3, 'row 3') DECLARE @DeleteLog AS TABLE (LogID INT, LogEntry VARCHAR(MAX)) DELETE OutputTest OUTPUT DELETED.ID, DELETED.Description INTO @DeleteLog WHERE ID = 1 SELECT *into DeleteLog FROM @DeleteLog select * from DeleteLog TIP 3: Standard table create statement, with getdate() for automatically recording the time when a record was added. CREATE TABLE [junk23]( [JunkID] [smallint] IDENTITY(1,1) NOT NULL, [Name] varchar(20) NOT NULL, [ModifiedDate] [datetime] NOT NULL DEFAULT (getdate())) TIP 4: create PROCEDURE Insert_Top as /* CREATE TABLE [dbo].[top]( [SPID] [float] NULL, [Status] [nvarchar](255) NULL, [Login] [nvarchar](255) NULL, [HostName] [nvarchar](255) NULL, [BlkBy] [nvarchar](255) NULL, [DBName] [nvarchar](255) NULL, [Command] [nvarchar](255) NULL, [CPUTime] [float] NULL, [DiskIO] [float] NULL, [LastBatch] [nvarchar](255) NULL, [ProgramName] [nvarchar](255) NULL, [SPID1] [float] NULL, [REQUESTID] [float] NULL, [ModifiedDate] [datetime] NULL CONSTRAINT [DF_top_ModifiedDate] DEFAULT (getdate()) ) ON [PRIMARY] */ INSERT INTO [DPart_P008_Dev].[dbo].[top] ( [SPID], [Status], [Login], [HostName], [BlkBy], [DBName], [Command], [CPUTime], [DiskIO], [LastBatch], [ProgramName], [SPID1], [REQUESTID]) EXEC sp_who2 Now, create the loop procedure: create PROCEDURE Loop_Insert_Top as WHILE (1=1) BEGIN EXEC insert_top WAITFOR DELAY '00:01:00'; END To view the records: select * from [top] TIP 5: sp_help sp_helptext Insert_Page7_into_Combined_sproc "All that really happens when you create a procedure is that its syntax is checked and its source code is inserted into the syscomments system table" TIP 6: Getting a directory listing of the c:\ drive. -- To allow advanced options to be changed. EXEC sp_configure 'show advanced options', 1 GO -- To update the currently configured value for advanced options. RECONFIGURE GO -- To enable the feature. EXEC sp_configure 'xp_cmdshell', 1 GO -- To update the currently configured value for this feature. RECONFIGURE GO EXEC master..xp_cmdshell "dir c:\*" TIP 7: select 'Name' = o.name, 'Owner' = user_name(ObjectProperty( object_id, 'ownerid')), 'Object_type' = substring(v.name,5,31) --into t_sp_help from sys.all_objects o, master.dbo.spt_values v where o.type = substring(v.name,1,2) collate database_default and v.type = 'O9T' and substring(v.name,5,31) ='stored procedure' and user_name(ObjectProperty( object_id, 'ownerid'))='dbo' order by [Owner] asc, Object_type desc, Name asc TIP 8: You may need indexes. Try running the following query to see if the value is above 5000. SELECT * FROM (SELECT user_seeks * avg_total_user_cost * (avg_user_impact * 0.01) AS index_advantage, migs.* FROM sys.dm_db_missing_index_group_stats migs) AS migs_adv INNER JOIN sys.dm_db_missing_index_groups AS mig ON migs_adv.group_handle = mig.index_group_handle INNER JOIN sys.dm_db_missing_index_details AS mid ON mig.index_handle = mid.index_handle ORDER BY migs_adv.index_advantage TIP 9: Need to see what users are doing? select * from sys.dm_exec_sessions TIP 10: Need the last day of the month? Select dateadd(mm,1,convert(datetime,convert(char(10),getdate(),110)) - day(getdate())+1)-1 TIP 11: Put last day of month into a user defined function. create FUNCTION dbo.GetLastDayOfMonth() RETURNS datetime AS BEGIN DECLARE @OutDate datetime set @OutDate = (Select dateadd(mm,1,convert(datetime,convert(char(10),getdate(),110)) - day(getdate())+1)-1) RETURN(@OutDate) END Now call it: select dbo.GetLastDayOfMonth() TIP 12: Need a function that gets the date a year ago at the beginning of the month? create FUNCTION dbo.Get1YearAgo() RETURNS datetime AS BEGIN DECLARE @OutDate datetime set @OutDate = (Select dateadd(mm,-12,convert(datetime,convert(char(10), getdate(),110)) - day(getdate())+1) ) RETURN(@OutDate) END select dbo.Get1YearAgo() TIP 13: Need to get a list of all stored procedures? SELECT name FROM dbo.sysobjects WHERE type = 'P' AND category = 0 TIP 14: Need to get the median? Also see TIP 15 below and TIP 19. SELECT Median=AVG(c1) FROM ( SELECT MIN(c1) AS c1 FROM ( SELECT TOP 50 PERCENT col AS c1 FROM table ORDER BY c1 DESC) t UNION ALL SELECT MAX(c1) FROM ( SELECT TOP 50 PERCENT col AS c1 FROM table ORDER BY c1) t ) M (Also reference: http://www.sqlmag.com/Article/ArticleID/49827/49827.html) But note, you can probably use the sp_executesql statement as well. Here's a way to get the 75%. WITH T AS ( SELECT [Sls Rep],[Prod No],[UOM],[Unit Sales $], ROW_NUMBER() OVER(PARTITION BY [Sls Rep],[Prod No],[UOM] ORDER BY [Unit Sales $]) AS RowNum, COUNT(*) OVER(PARTITION BY [Sls Rep],[Prod No],[UOM]) AS Cnt FROM Pg7_all_trans ) SELECT [Sls Rep],[Prod No],[UOM],Avg([Unit Sales $]) [Median Unit Sales $], Max(RowNum) [RowNum], Max(Cnt) [Cnt] into Pg7_75 FROM T WHERE RowNum >= 0.75*(Cnt+1) and RowNum <= 0.75*(Cnt+2) GROUP BY [Sls Rep],[Prod No],[UOM] TIP 15: sp_executesql -- Executing the contents of a string as a SQL statement. Declare @S nvarchar(500); set @S = 'select * from' + ' junk' execute sp_executesql @S But wait! You can do this in a sproc: create proc select_table(@a as nvarchar(50)) as Declare @t as nvarchar(500); set @t = 'select * from ' + @a; execute sp_executesql @t Now just run this as follows: select_table 'junk'; Here's another example with parameters: EXECUTE sp_executesql N'SELECT * FROM AdventureWorks.HumanResources.Employee WHERE ManagerID = @level', N'@level tinyint', @level = 109; Here's an example with quotes: Declare @S nvarchar(max); set @S = ' IF object_id(''junk'') IS NOT NULL BEGIN DROP TABLE junk END create table junk (a int, b varchar(20)); insert into junk (a,b) values (1,''one''); insert into junk (a,b) values (2,''two''); select * from junk; ' -- print @S execute sp_executesql @S (Also reference: http://msdn2.microsoft.com/en-us/library/ms188001.aspx) TIP 16: More sp_executesql -- DECLARE @sql AS NVARCHAR(MAX), @i AS INT; SET @sql = N''; SET @i = 1; WHILE @i <= 100 BEGIN SET @sql = @sql + N'PRINT ' + CAST(@i AS NVARCHAR(10)) + NCHAR(13) + NCHAR(10); SET @i = @i + 1; END EXEC sp_executesql @sql; TIP 17: Simple example of a union statement: select * into t1_t2_combined from (select * from t1 union select * from t2) as a TIP 18: Need to find SQL version? SELECT @@VERSION or SELECT SERVERPROPERTY('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition') Reference: http://support.microsoft.com/kb/321185 TIP 19: Example calculating Median on the table Median_table GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO alter FUNCTION [dbo].[calc_median_product_uom] (@product as nvarchar(30), @uom as nvarchar(4) ) -- Created: Mike Chirico <firstname.lastname@example.org> -- Updated: Thu Sep 27 16:30:20 EDT 2007 -- -- Example Usage: -- -- select product,uom,DPart_P008.dbo.calc_median_product_uom(product,uom) Median from Median_table -- -- RETURNS money AS BEGIN DECLARE @Median as money SELECT @Median=AVG(c1) FROM ( SELECT MIN(c1) AS c1 FROM (SELECT TOP 50 PERCENT AvqPrice AS c1 FROM Median_table where product=@product and uom=@uom ORDER BY c1 DESC ) as t UNION ALL select max(c1) as c1 from ( SELECT TOP 50 PERCENT AvqPrice AS c1 FROM Median_table where product=@product and uom=@uom ORDER BY c1 ) as t ) M RETURN(@Median) END TIP 20: Example listing all the indexes on table mytable. select a.name table_name, b.name index_name, d.name column_name, c.index_column_id from sys.tables a, sys.indexes b, sys.index_columns c, sys.columns d where a.object_id = b.object_id and b.object_id = c.object_id and b.index_id = c.index_id and c.object_id = d.object_id and c.column_id = d.column_id and a.name = 'mytable' TIP 21: Need a comparison between Oracle 10g and SQL 2005? Take a look at the following: http://www.wisdomforce.com/dweb/resources/docs/MSSQL2005_ORACLE10g_compare.pdf TIP 22: Need to free up space? The following query shows how much space can be freed. SELECT name ,size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0 AS AvailableSpaceInMB FROM sys.database_files; To free up space from the database 'mydatabase' use the following command: DBCC SHRINKDATABASE('mydatabase',0); To free up sapce from the logfile 'mylogfile' use the following command: DBCC SHRINKFILE('mylogfile',0); TIP 23: Getting the Sum, Max across rows in a table. Assume a simple table defined as follows: create table junk (a int, b int, c int); insert into junk (a,b,c) values (1,4,3); insert into junk (a,b,c) values (2,5,9); insert into junk (a,b,c) values (3,8,2); select *, (select sum(my_columns) from (select a as my_columns union all select b union all select c) as t) as sum_column from junk Tip 24: Delete all tables with the name delete in them. SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: <Mike Chirico email@example.com> -- Create date: <Thu Nov 1 08:34:41 EDT 2007> -- Description: <This proc will go through and delete -- all tables with the name delete in them.> -- ============================================= alter PROCEDURE free_space AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; DECLARE cursor_value CURSOR FOR select name from sys.tables where name like '%delete%' FOR READ ONLY DECLARE @cursor_row_value varchar(120) DECLARE @S nvarchar(500); OPEN cursor_value FETCH cursor_value INTO @cursor_row_value WHILE (@@FETCH_STATUS=0) BEGIN set @S = 'drop table ['+@cursor_row_value+']' execute sp_executesql @S FETCH cursor_value INTO @cursor_row_value END CLOSE cursor_value DEALLOCATE cursor_value END GO TIP 25: What is the difference between UNION and UNION ALL? UNION only returns the distinct number of rows and is slower than UNION ALL. TIP 26: What is the difference between NVARCHAR, VARCHAR and CHAR? NVARCHAR takes two bytes, VARCHAR takes 1 byte, and CHAR is fixed length. TIP 27: Order can make a difference when doing updates IF object_id('tempdb..#t1') IS NOT NULL BEGIN DROP TABLE #t1 END IF object_id('tempdb..#t2') IS NOT NULL BEGIN DROP TABLE #t2 END IF object_id('tempdb..#t3') IS NOT NULL BEGIN DROP TABLE #t3 END create table #t1 (a int, b int); insert into #t1 (a,b) values (1,2); insert into #t1 (a,b) values (1,5); create table #t2 (a int ,b int, c int, d int, [order] int); insert into #t2 (a,b,c,d,[order]) values (1,2,10,10,0); insert into #t2 (a,b,c,d,[order]) values (1,2,50,60,1); -- Change order here: --select * into #t3 from #t2 order by [order] desc select * into #t3 from #t2 order by [order] asc update #t1 set #t1.a=#t3.c, #t1.b=#t3.d from #t1 ,#t3 where #t1.a=#t3.a and #t1.b=#t3.b select * from #t1 TIP 28: Need a listing of all stored procedures on the system that you created? SELECT * -- Stored Procs FROM sys.objects WHERE objectproperty( object_id, N'IsMSShipped' ) = 0 AND objectproperty( object_id, N'IsProcedure' ) = 1 Below are some other common methods. But take a look at the following below and note the condition where N'IsMSShipped' is false, or equal to zero. SELECT * -- Functions FROM sys.objects WHERE objectproperty( object_id, N'IsMSShipped' ) = 0 AND ( objectproperty( object_id, N'IsTableFunction' ) = 1 OR objectproperty( object_id, N'IsScalarFunction' ) = 1 ) SELECT * -- User tables FROM sys.objects WHERE objectproperty( object_id, N'IsMSShipped' ) = 0 AND objectproperty( object_id, N'IsTable' ) = 1 SELECT * -- Views FROM sys.objects WHERE objectproperty( object_id, N'IsMSShipped' ) = 0 AND objectproperty( object_id, N'IsView' ) = 1 Reference: http://msdn2.microsoft.com/en-us/library/ms176105.aspx http://sqlblogcasts.com/blogs/tonyrogerson/archive/2006/06/29/850.aspx TIP 29: Combining two tables into 1 pivot table create table p1 (a int, b int) create table p2 (a int, b int) delete from p1; delete from p2; insert into p1 (a,b) values (1,34); insert into p1 (a,b) values (2,12); insert into p1 (a,b) values (3,22); insert into p2 (a,b) values (1,500); insert into p2 (a,b) values (2,512); insert into p2 (a,b) values (4,600); select g.a,g.b,g.c from ( select p1.a, p1.b,p2.b as c from p1, p2 where p1.a=p2.a union all select p1.a,p1.b,null as c from p1 left outer join p2 on p1.a=p2.a where p2.a is null union all select p2.a,null as b,p2.b as c from p2 left outer join p1 on p2.a=p1.a where p1.a is null ) as g /* Results: a b c 1 34 500 2 12 512 3 22 NULL 4 NULL 600 */
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Gmail on Home Linux Box using Postfix and Fetchmail If you have a Google Gmail account, you can relay mail from your home linux system. It's a good exercise in configuring Postfix with TLS and SASL. Plus, you will learn how to bring down the mail safely, using fetchmail with the "sslcertck" option.
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Mike Chirico, a father of triplets (all girls) lives outside of
Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters
in Computer Science and Mathematics from Villanova University, and has
worked in computer-related jobs from Wall Street to the University of
Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was
known for his open collaboration with others.
Mike's notes page is souptonuts. For open source consulting needs, please send an email to firstname.lastname@example.org. All consulting work must include a donation to SourceForge.net.