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Sql Server useful commands

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Categories: SQL, SQL Server Tags: ,

Logging by Triggers in SQL Server

We can alternatively use SQL Server feature CDC (Change Data Capture), but here I am providing one more way of doing it (custom solution).

Db Objects: (two tables and two triggers)

  1. TargetTableName: Table whose data we want to log
  2. LogTableName: Table where data will be logged. This table structure will be same as TargetTableName, and additionally this table will have three extra columns namely
    • [log_action_type]
    • [log_action_date]
    • [log_action_user]
    • [log_action_hostname]
  3. tl_TargetTableName: Trigger to log DML changes (Update and Delete only)
  4. tu_LogTableName: Trigger to avoid Delete or Update operations operations on logging table
 
use dbname
go

alter table LogTableName add [log_action_type] 	[char](1) not null;
alter table LogTableName add [log_action_date] 	[datetime] not null default getdate();
alter table LogTableName add [log_action_user] 	[varchar](50) null;
alter table LogTableName add [log_action_hostname] 	[varchar](50) default host_name();

go

IF OBJECT_ID ('dbo.tu_LogTableName ','TR') IS NOT NULL
   DROP TRIGGER dbo.tu_LogTableName;
GO
-- =============================================
-- Author:		Umesh Patil	
-- Create date: 2014/08/26
-- Description:	Restirct Delete or Update operations operations on logging table
-- =============================================
CREATE TRIGGER dbo.tu_LogTableName  
   ON  dbo.LogTableName 
   FOR DELETE,UPDATE
AS 
BEGIN
	RAISERROR ('Can not perform Delete or Update operations on UserTableName table, either disable/delete the trigger',16,1);
	ROLLBACK TRANSACTION;
	RETURN;
END
GO

use dbname
go

IF OBJECT_ID ('dbo.tl_TargetTableName','TR') IS NOT NULL
   DROP TRIGGER dbo.tl_TargetTableName;
GO
-- =============================================
-- Author:		Umesh Patil	
-- Create date: 2014/08/26
-- Description:	Log DML changes (Update and Delete only)
-- =============================================
CREATE TRIGGER dbo.tl_TargetTableName 
   ON  dbo.TargetTableName
   FOR DELETE,UPDATE
AS 
BEGIN
	SET NOCOUNT ON;
	DECLARE @ActionType char(1)

	IF EXISTS (SELECT 1 FROM deleted)
		BEGIN
			IF EXISTS(SELECT 1 FROM inserted)
				SET @ActionType='U'
			ELSE
				SET @ActionType='D'
		END

	IF  @ActionType='U' OR  @ActionType='D'
		INSERT INTO [dbo].[TargetTableName]
           	([PrimaryKey_Column]
		  --include all columns
		,[log_action_type]
		,[log_action_date]
		,[log_action_user]
		  ,[log_action_hostname])
		select		
			[PrimaryKey_Column]
			--include all columns
			,@ActionType as [log_action_type]
			,getdate() as [log_action_date]
			,suser_sname() as [log_action_user]
			,host_name() as [log_action_hostname]
		from deleted
END
GO
Categories: SQL, SQL Server, T-SQL Tags: , ,

Find Non-ASCII character in SQL Server

Here is a simple command to find character.

SELECT
	NOTES
	,patindex('%[' + CHAR(127)+ '-' +CHAR(255)+']%' COLLATE Latin1_General_BIN,NOTES) as [Position]
	,substring(NOTES,patindex('%[' + CHAR(127)+ '-' +CHAR(255)+']%' COLLATE Latin1_General_BIN,NOTES),1) as [InvalidCharacter]
	,ascii(substring(NOTES,patindex('%[' + CHAR(127)+ '-' +CHAR(255)+']%' COLLATE Latin1_General_BIN,NOTES),1)) as [ASCIICode]
FROM
      tablename (NOLOCK)
WHERE
      Notes LIKE '%[' + CHAR(127)+ '-' +CHAR(255)+']%'  COLLATE Latin1_General_100_BIN2

Hope it helps.

Regards,
Umesh

Categories: Data Quality, SQL, T-SQL Tags: ,

Understand Response Time vs. Total Time in SQL

June 8, 2012 Leave a comment

Response time is the time it takes for a query to return the first record. Total time is the time it takes for the query to return all records. For an interactive application, response time is important because it is the perceived time for the user to receive visual affirmation that a query is being processed. For a batch application, total time reflects the overall throughput. You have to determine what the performance criteria are for your application and queries, and then design accordingly.

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