Today, I am going to talking about common table expressions. A common table expression (CTE) is a temporary result set that is defined within the execution scope of a single DML statement. A CTE is simular to a derived table in which the results are not stored as an object; However, CTE’s can be recursive or built upon other CTE’s. The WITH key word is used to indicate the start of a CTE and needs to be preceeded with a semicolon. The rest of the syntax is like a stored…
Tag: John F. Miner III
Temporary Tables – Part 4
Today, I am going to talk about regular tables in tempdb. Please check out the Microsoft white paper on working with tempdb for a detailed discussion. The advantage of creating a table in tempdb is that it is persistent until the server is rebooted. Upon startup of SQL Server, tempdb is created again from scratch. One use of this technique is to have startup procedures create tables in tempdb that are used by an application program. One can leverage the fact that operations within tempdb are minimally logged. The major…
Temporary Tables – Part 3
Today, I am going to talk about table variables. In general, TSQL variables are defined by using the DECLARE key word and preceeding the variable name with a @ sign. Table variables are created by using the TABLE key word just after the variable name. The declaration following this key word includes column definitions — names, data types, and constraints. The only constraint types allowed in the declaration are PRIMARY KEY, UNIQUE, NULL, and CHECK. Indexes are a bi-product of a PRIMARY and UNIQUE constraints. The scope of a table…
Temporary Tables – Part 2
Today, I am going to talk about local and global temporary tables. A local temporary table is defined by using the CREATE TABLE syntax with the name of the table prefixed by one number sign #. The scope of the local temporary table is the current session or SPID. A global temporary table is defined by using the CREATE TABLE syntax with the name of the table prefixed by two number signs ##. The table is visible to all sessions. The scope of the global temporary table is the current…
Temporary Tables – Part 1
Today, I am going to be starting a series of articles on temporary tables. I will be focusing on derived tables. A derived table is a sub-query that is used to as input to the outer query. An table alias should be used outside the parenthesis to reference the inner query. I think of derived tables as a cross between temporary tables and dynamic views that go away after the query executes. The first example of a derived table creates the car ownership table for person a. Please see the…
Testing Alerts
Having set up system and performance alerting, it is now time to test those darn alerts to make sure they work! Alerting can notify a operator via email, paging, or a net send messages. Now adays, most people have a smart phone, not an old fashion pager. Therefore, I usually create a Active Directory group that has both the regular company email of the DBA group and their cell phone eqivalents which are usually the phone number @ provider name dot com. Today, I am going to talk about two…
Performance Alerts
Today, I am going to talk about setting up performance alerts so that you can notified when a server has issues. Basically, there are two types of performance alerts, SQL Server and WMI. I am going to use the sp_add_category system procedure to define a peformance category.
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-- Add a custom category for alerts EXEC msdb.dbo.sp_add_category @class=N'ALERT', @type=N'NONE', @name=N'[Alert By Performance]' ; GO -- Show Alert categoryes EXEC msdb.dbo.sp_help_category @class=N'ALERT' GO |
The sp_add_alert stored procedure is used to create the alert and the sp_add_notification stored procedure is used to associate the alert with an operator. This process is used below to show examples of both SQL and WMI performance alerts. The first type…
Defining Operators
SQL Server supports the notification of administrators through operators. Operators are aliases for users or groups that can receive notifications when jobs complete or alerts have been raised. Each SQL Server instance can have its own set of defined operators. Today, I am going to walk you thru the following tasks in Transaction SQL. Adding an operator Updating an operator Deleting an operator Defining a fail-safe operator To define an operator, one needs to know the email address of the user and what time he is responsible for the SQL…
Database Mail – Part 1
Database Mail is an enterprise solution for sending e-mail messages from the SQL Server Database Engine. It is very important to configure mail on any server that you manage. Error and performance alerting as well as SQL agent job outcomes depend upon this service for notifications. I am going to copy a paragraph directly from Microsoft TechNet since I can not say it in any better in my own words. Database Mail is designed on a queued architecture that uses service broker technologies. When users execute sp_send_dbmail, the stored procedure…
DBA – Introduction
Today, I am going to start writing another topic thread for Database Administration (DBA). I do alot of DBA work among many other things at my current job. I am going to cheat a little by copying a list from a renown SQL Server MVP named Paul Randal. This list was published in a TechNet Magazine article in November, 2010. To be a succesful database administrator, you should start working your way through the following tasks (secrets) to manage choas at your organization.
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10. Take Inventory 9. Standardize Configurations 8. Understand the I/O Subsystem 7. Create a Customized Maintenance Plan 6. Ensure the Security of Your System 5. Get on Good Terms with Your Developers 4. Develop a Comprehensive Disaster Recovery Strategy 3. Take and Test Regular Backups 2. Monitor and Maintain Performance 1. Know Where to Find Information |
In the coming weeks, I am…