In this article, we will discuss typical errors that newbie developers may face with while designing T-SQL code. In addition, we will have a look at the best practices and some useful tips that may help you when working with SQL Server, as well as workarounds to improve performance.
In the previous article, we analyzed how to compare objects by value on a particular example with the Person class that includes:
- Overriding the GetHashCode() andObject.Equals(Object) methods;
- Implementation of the IEquatable (Of T) interface;
- Implementation of the type-specific static method Equals(Person, Person) and operators ==(Person, Person), !=(Person, Person).
Sooner or later, a DB administrator would like to have a performance indicator for SQL Server queries. As we all know, running Profiler for 24 hours will lead to a considerable system load and therefore, it cannot be considered an optimal solution for databases used in the 24/7 mode.
So, how can we detect the state of SQL Server queries? How can we run trace for detected query-related problems without the human input?
In this article, I will provide an implementation of the SQL Server performance indicator for queries, stored procedures and triggers, as well as its usage for the trace run. Read More
The World Wide Web offers a bunch of information on SQL Server index defragmentation or SQL Server index rebuild. However, most of the recommendations refer to databases that have minimum load time (mostly, at night).
And what about databases that are used for both, data modification, and retrieving information on a 24/7 basis?
In this article, I will provide a mechanism for automating SQL Server index defragmentation implemented in a database used in the company I work for. This mechanism allows defragmenting required indexes on a regular basis since index fragmentation takes place constantly in the 24/7 system. Often, this is not enough to perform index defragmentation once a day. Read More
What are unique key constraints?
A unique constraint is a rule that restricts column entries to unique. In other words, this type of constraints prevents inserting duplicates into a column. A unique constraint is one of the instruments to enforce data integrity in an SQL Server database. Since a table can have only one primary key, you can use a unique constraint to enforce the uniqueness of a column or a combination of columns that do not constitute a primary key.
Creating a unique constraint on a column automatically creates a unique index. This way SQL Server implements the integrity requirement of the unique constraint. Therefore, when attempting to insert a duplicate value into a column, on which a unique constraint is defined, the Database Engine will detect the unique constraint violation and issue a corresponding error. As a result, the row with the duplicate values will not be added to a table.
Now, we will explore a type-specific implementation of how to compare objects by value including the IEquatable(Of T) generic interface and overload of “==” and “!=” operators.
Type-specific comparison of objects by value allows achieving:
- a more stable, scalable and mnemonic (readable) code through overloaded operators;
- higher performance.
Recently, I was involved in the development of the functionality that required a fast and frequent transfer of large volumes of data to disc. In addition, this data was supposed to be read from disk from time to time. Therefore, I was destined to find out the place, the way and the means for storing this data. In this article, I will briefly review the task, as well as investigate and compare solutions for completion of this task.
Context of the task: I work in a team that develops tools for relative database development (SQL Server, MySQL, Oracle). The tool range includes both, standalone tools, and add-ins for MS SSMS.
Task: Restoring documents that were opened at the moment of IDE closing at the next start of IDE. Read More
Parsing data from XML using XQuery is a routine practice. In order to do this most effectively, little effort is required.
Suppose we need to parse data from the disk file with the following structure:
<tables> <table name="Accounting" schema="Production" object="Accounting"> <column name="Date" order="3" visible="1" /> <column name="DateFrom" order="5" visible="1" /> <column name="DateTo" order="6" visible="1" /> <column name="Description" order="4" visible="1" /> <column name="DocumentUID" order="1" visible="0" /> <column name="Number" order="2" visible="1" /> <column name="Warehouse" order="7" visible="1" /> </table> </tables>
Use BULK INSERT, if you need to read data from a file:
SELECT BulkColumn FROM OPENROWSET(BULK 'D:\data.xml', SINGLE_BLOB) x sample xml file
This article helps to enrich the functionality of SSIS. It is possible for example to set properties in tasks using expressions and we can assign values and create code to enrich the SSIS functionality.
This article is oriented to SSIS developers who have experience with basic tasks, but are not familiar with variables, scripts to enrich the functionality of the SSIS and to provide dynamic functionality.
This time we will talk about SSIS expressions, variables, and loops in SSIS. We will use expressions to set values in tasks using variables. We will also learn to create Script code in C#.
We will first talk about SSIS expressions and then we will use SSIS with the script task. Finally, we will work with Loop containers and the script task.Read More
In the previous article, we have reviewed a general concept of implementing a minimum set of required modifications that include overriding the Object.Equals(Object) and Object.GetHashCode() methods in order to compare class objects by value on a standard .NET framework.
Let’s consider the implementation features of the Object.Equals(Object) method so that it meets the following documentation requirement:
x.Equals(y) returns the same value as y.Equals(x).