Month: October 2018

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SQL Server Database Engine

The "IGNORE_DUP_KEY" option in Primary Keys and Unique Indexes

Unlike foreign keys, primary keys and unique indexes cannot be “untrusted”. There’s no “NOCHECK” option for unique constraints. The closest there is, is the “ignore_dup_key” option. “Hmm… That sounds interesting”, you must be thinking. But let me stop you right there, buddy. Read this before you go off doing something potentially dangerous… Very, VERY dangerous. But it does NOT mean that you can create such … Continue reading The "IGNORE_DUP_KEY" option in Primary Keys and Unique Indexes

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T-SQL

Let SQL Server Write Code for You

Many times I happen to find myself in a situation where, as a DBA, I need to write some long and cumbersome code (usually for maintenance purposes). For example: Write a script to copy a bunch of tables from one database to another. Import the tables from one database to another database. Rebuild a bunch of indexes. Update a bunch of statistics. Write scripts for … Continue reading Let SQL Server Write Code for You

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SQL Server Performance, T-SQL

Efficiently UPDATE and DELETE using TOP and ORDER BY

Since SQL Server 2005, Microsoft had a nice addition to the common DML statements, UPDATE and DELETE, by allowing the use of the TOP keyword. Well, we’re now in the year 2018 and SQL Server 2019 is just around the corner, and yet unfortunately for many of us, SQL Server still doesn’t support the use of the TOP keyword in direct conjunction with the ORDER … Continue reading Efficiently UPDATE and DELETE using TOP and ORDER BY

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SQL Server Database Engine, SQL Server Performance

The Curious Case of Collations and Performance in SQL Server

One fateful night, cold and dreary, I’ve stumbled upon an apparently little known fact about SQL Server – specifically SQL Server collations and how they affect performance… Yes, really!

While normalizing a table in their database, one of my clients had weird and inconsistent performance problems and couldn’t find a solution for it for quite a while. Continue reading The Curious Case of Collations and Performance in SQL Server

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T-SQL

Remove the IDENTITY property from an existing column

How to remove the IDENTITY property from an existing column using T-SQL (without changing the order of the columns or moving the data into a new table) Recently I had a scenario at a client where I needed to remove the IDENTITY property of a column in an existing table. The two common methods to do this were quite problematic and were no good for … Continue reading Remove the IDENTITY property from an existing column

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SQL Server Database Engine, Tools and Scripts

Using Reporting Services as your Software Frontend

CREATE PROCEDURE MoveEmployeesFromManagerToManager @SourceManagerID INT, @DestinationManagerID INT AS DECLARE @RCount INT DECLARE @Output AS TABLE ( Msg NVARCHAR(MAX) ) BEGIN TRY INSERT INTO @Output VALUES( N’Moving employees from ManagerID ‘ + CONVERT(nvarchar(50), @SourceManagerID) + ‘ to ManagerID ‘ + CONVERT(nvarchar(50), @DestinationManagerID) + ‘…’ ) BEGIN TRANSACTION UPDATE Employees SET ManagerID = @DestinationManagerID OUTPUT N’Moved EmployeeID ‘ + CONVERT(nvarchar(50), INSERTED.EmployeeID) INTO @Output FROM HumanResources.Employee AS Employees … Continue reading Using Reporting Services as your Software Frontend

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