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Commit 1ccad56

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Trigers & Functions
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‎.vs/slnx.sqlite

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‎Triger_Functions/DDL.sql

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Use WideWorldImporters-Pluralsight;
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GO
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/*
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Create a DDL trigger in this current database that prevents
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altering or dropping a table
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*/
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CREATE OR ALTER TRIGGER TDB_PreventTableDropOrAlter
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ON DATABASE
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FOR DROP_TABLE,ALTER_TABLE
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AS
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BEGIN
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PRINT 'DROP and ALTER table events are not allowed. Disable trigger TDB_PreventTableDropOrAlter to complete action.'
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ROLLBACK
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END
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/*
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Attempt to drop our Audit Log table
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*/
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DROP TABLE Application.AuditLog;
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/*
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Attempt to add a column to the Application.Person table
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*/
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ALTER TABLE Application.People ADD TwitterHandle nvarchar(100);
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/*
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Disable the trigger so that we can complete our modification;
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*/
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DISABLE TRIGGER TDB_PreventTableDropOrAlter ON DATABASE;
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/*
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Attempt to add a column to the Application.Person table again
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*/
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ALTER TABLE Application.People ADD TwitterHandle nvarchar(100);
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/*
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Enable the trigger again
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*/
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ENABLE TRIGGER TDB_PreventTableDropOrAlter ON DATABASE;
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GO
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/*************************************
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*
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* Log DDL Events to a table
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*
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*************************************/
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CREATE TABLE Application.AuditLogDDL
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(
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Id INT IDENTITY,
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EventTime DATETIME,
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EventType NVARCHAR(100),
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LoginName NVARCHAR(100),
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Command NVARCHAR(MAX)
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)
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GO
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/*
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This will log ALL DDL events at the database level.
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In reality, this should be refined to only capture events
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on specific types OR this audit table should be aggressively
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managed to only keep relevant events and table size small.
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*/
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CREATE TRIGGER AuditLogDDLEvents
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ON DATABASE
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FOR DDL_DATABASE_LEVEL_EVENTS
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AS
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BEGIN
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SET NOCOUNT ON
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DECLARE @EventData XML = EVENTDATA()
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INSERT INTO Application.AuditLogDDL(EventTime,EventType,LoginName,Command)
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SELECT @EventData.value('(/EVENT_INSTANCE/PostTime)[1]', 'DATETIME'),
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@EventData.value('(/EVENT_INSTANCE/EventType)[1]', 'VARCHAR(100)'),
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@EventData.value('(/EVENT_INSTANCE/LoginName)[1]', 'VARCHAR(100)'),
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@EventData.value('(/EVENT_INSTANCE/TSQLCommand/CommandText)[1]', 'NVARCHAR(MAX)')
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END
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/*
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Now, let's perform some DDL Events and see what we get
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*/
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/*
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Attempt to add a column to the Application.Person table
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*/
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ALTER TABLE Application.People ADD InstagramHandle nvarchar(100);
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/*
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Check the Log
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*/
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SELECT * FROM Application.AuditLogDDL;
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/*
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Disable the trigger so that we can complete our modification;
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*/
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DISABLE TRIGGER TDB_PreventTableDropOrAlter ON DATABASE;
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/*
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Attempt to add a column to the Application.Person table again
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*/
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ALTER TABLE Application.People ADD InstagramHandle nvarchar(100);
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/*
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Check the Log
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*/
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SELECT * FROM Application.AuditLogDDL;
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/*
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Enable the trigger again
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*/
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ENABLE TRIGGER TDB_PreventTableDropOrAlter ON DATABASE;
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GO
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‎Triger_Functions/INSERT_AFTER.sql

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‎Triger_Functions/INSERT_INSTEAD_OF.sql

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USE master;
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GO
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/*
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Create a new local login to test LOGON Triggers.
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ONLY do something like this in a local, non-shared environment!
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*/
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CREATE LOGIN login_test WITH PASSWORD = 'abc123!';
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GO
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/*
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Grant them access to see DMVs. There are many better ways to
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accomplish this in production, but this will work for the demo.
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*/
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GRANT VIEW SERVER STATE TO login_test;
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GO
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/*
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Create a LOGON trigger that will limit the number of connections
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for this specific user. They cannot open more than 2 connections.
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*/
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CREATE OR ALTER TRIGGER LimitConnectionsForUser
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ON ALL SERVER
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FOR LOGON
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AS
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BEGIN
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IF ORIGINAL_LOGIN()= 'login_test' AND
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(SELECT COUNT(*) FROM sys.dm_exec_sessions
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WHERE is_user_process = 1 AND
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original_login_name = 'login_test') > 2
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ROLLBACK;
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END;
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/***********************************************
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*
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* Create a server-level audit logging database
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*
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**********************************************/
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/*
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Create an Audit Log Database for server-level events. This
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will be owned by my local user for now.
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*/
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CREATE DATABASE AuditLogDB;
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GO
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USE AuditLogDB;
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GO
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/*
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Create a table within the new database to store login event data
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*/
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CREATE TABLE LogonEventData
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(
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LogonTime datetime,
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SPID int,
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HostName nvarchar(50),
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AppName nvarchar(100),
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LoginName nvarchar(50),
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ClientHost nvarchar(50)
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);
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GO
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/*
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Create a second LOGON Trigger to log information.
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This will be executed each time as the owner of the logging
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database. Without this, the Trigger would be executed as the
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CALLER ('test_login' in this case) and it would return an error
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because they do not have permission to write into that
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database.
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Much care and thought should be given to how permissions are
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used within your environments to protect data and users
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appropriately.
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*/
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CREATE OR ALTER TRIGGER SuccessfulLogonAudit
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ON ALL SERVER WITH EXECUTE AS 'RYANB-DEV\Ryan'
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FOR LOGON
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AS
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BEGIN
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DECLARE @LogonTriggerData xml,
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@EventTime datetime,
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@SPID int,
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@LoginName nvarchar(50),
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@ClientHost nvarchar(50),
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@LoginType nvarchar(50),
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@HostName nvarchar(50),
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@AppName nvarchar(100);
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SET @LogonTriggerData = EventData();
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SET @EventTime = @LogonTriggerData.value('(/EVENT_INSTANCE/PostTime)[1]', 'datetime');
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SET @SPID = @LogonTriggerData.value('(/EVENT_INSTANCE/SPID)[1]', 'int');
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SET @LoginName = @LogonTriggerData.value('(/EVENT_INSTANCE/LoginName)[1]', 'nvarchar(50)');
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SET @ClientHost = @LogonTriggerData.value('(/EVENT_INSTANCE/ClientHost)[1]', 'nvarchar(50)');
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SET @HostName = HOST_NAME();
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SET @AppName = APP_NAME();
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INSERT INTO AuditLogDB.dbo.LogonEventData
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(
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LogonTime, SPID, HostName, AppName, LoginName, ClientHost
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)
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VALUES
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(
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@EventTime, @SPID, @HostName, @AppName, @LoginName, @ClientHost
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)
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END
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GO
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/*
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Create a new query window and check the log
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*/
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SELECT * FROM AuditLogDB.dbo.LogonEventData
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ORDER BY LogonTime DESC;
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/*
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We can reset the order of these Triggers. Because everything is run in
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the same transaction, more work would be needed to log attempts that
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are successful but cross the number of connections limit.
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*/
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sp_settriggerorder @triggername = 'SuccessfulLogonAudit', @order = 'first',
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@stmttype = 'LOGON', @namespace = 'SERVER';
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GO
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sp_settriggerorder @triggername = 'LimitConnectionsForUser', @order = 'last',
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@stmttype = 'LOGON', @namespace = 'SERVER';
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GO
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/*
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Cleanup
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*/
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DROP TRIGGER LimitConnectionsForUser ON ALL SERVER;
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DROP TRIGGER SuccessfulLogonAudit ON ALL SERVER;
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DROP DATABASE AuditLogDB;
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DROP LOGIN login_test;
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/*
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Look at a select statement with three built-in Scalar functions
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*/
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SELECT MONTH(GETDATE()) AS [MONTH], YEAR(GETDATE()) AS [YEAR];
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GO
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/*
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Create a very simple User-Defined, Multi-Statement Scalar Function
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*/
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CREATE OR ALTER FUNCTION dbo.SuperAdd_scaler(@a INT, @b INT)
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RETURNS INT
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WITH SCHEMABINDING
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AS
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BEGIN
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/*
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Although this just happens to be one statement, I can have more than
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one in a scalar function, so don't let that confuse you.
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*/
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RETURN @a + @b;
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END;
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GO
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/*
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Do simple addition
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*/
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select dbo.SuperAdd_scaler(2,2);
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GO
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/*
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Attempt to pass in bad data
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*/
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select dbo.SuperAdd_scaler('a',3);
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GO
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/*
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Create a slightly more complext Multi-Statement Scalar Function that
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returns the Fiscal Year Ending of a provided date/time.
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Defaulting to June as the default Fiscal Ending Month
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*/
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CREATE OR ALTER FUNCTION dbo.FiscalYearEnding(@SaleDate DATETIME, @FiscalEndMonth INT = 6)
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RETURNS INT
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WITH SCHEMABINDING
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AS
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BEGIN
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DECLARE @saleMonth INT = MONTH(@SaleDate);
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DECLARE @saleYear INT = YEAR(@SaleDate);
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DECLARE @fiscalYear INT = @saleYear;
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IF(@saleMonth > @FiscalEndMonth AND @FiscalEndMonth != 1)
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BEGIN
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SET @fiscalYear = @saleYear + 1;
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END;
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RETURN @fiscalYear;
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END;
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GO
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/*
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Select a given date and see if we get the correct year
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*/
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SELECT '2019年01月01日' SampleDate, dbo.FiscalYearEnding('2019年01月01日',1) FiscalYear; -- 2019
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SELECT '2019年07月01日' SampleDate, dbo.FiscalYearEnding('2019年07月01日',6) FiscalYear; -- 2020
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SELECT '2019年07月01日' SampleDate, dbo.FiscalYearEnding('2019年07月01日',7) FiscalYear; -- 2019
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SELECT '2019年12月01日' SampleDate, dbo.FiscalYearEnding('2019年05月01日',4) FiscalYear; -- 2020
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SELECT '2019年12月01日' SampleDate, dbo.FiscalYearEnding('2019年12月01日',12) FiscalYear; -- 2019
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/*
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Now on some real data
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*/
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SELECT TOP 100 OrderId, OrderDate, dbo.FiscalYearEnding(OrderDate, DEFAULT) as FiscalSaleYear from Sales.Orders
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WHERE OrderDate > '2013年06月28日'
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GO
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/*
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As stated earlier, Scalar Functions are often used in WHERE predicates. Unfortunately
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both of these examples are very inefficient because they prevent SARGability, which
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we'll discuss in a bit.
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These will both cause the Sales.Orders table to be scanned row-by-row to calculate the
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year and fiscal year respectively.
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Finding Orders based on YEAR
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*/
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SELECT TOP 100 OrderId, OrderDate, dbo.FiscalYearEnding(OrderDate, DEFAULT) as FiscalSaleYear from Sales.Orders
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WHERE YEAR(OrderDate) > 2015
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GO
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/*
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Using our new FiscalYearEnding function
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*/
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SELECT TOP 100 OrderId, OrderDate, dbo.FiscalYearEnding(OrderDate, DEFAULT) as FiscalSaleYear from Sales.Orders
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WHERE dbo.FiscalYearEnding(OrderDate,DEFAULT) > 2015
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GO
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‎Triger_Functions/Trigger_Order.sql

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‎Triger_Functions/UPDATE_AFTER.sql

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