In this article, we’ll walk-through the SQL Pivot and SQL Unpivot operators and how they can be useful to transpose SQL Server data. Also, we’ll discuss both static and dynamic ways to use PIVOT and UNPIVOT relational operators that can be used to transform aggregated distinct values as column(s) in the result-set by specifying all the column values in the PIVOT IN clause.Read more »
In this article, we’ll walk-through the SQL update statement to modify one or more existing rows in the table.Read more »
In this article, we are going to learn how to use the SQL LIKE operator, in SQL Server, using regular expressions to find and/or manipulate text. We will start by learning the symbols and basic syntax of using wildcard regular expressions. We will use character sets and repetition expressions to create flexible matching patterns, and along the way, we’ll examine different ways to use the LIKE operator. And then, finally, in the latter part of the section, we will explore some of the most common and most useful regular expression examples.Read more »
This article will provide a deep dive into the SQL Union operator, describing its many uses along with examples and explore some common questions like the differences between Union vs Union All.Read more »
We all know that a Null value is a field with no value. The statements that we are running daily will have to deal with Null values, especially when it comes to strings concatenation (adding strings together).Read more »
This article will provide an overview of the SQL Join and cover all of the SQL join types including inner, self, cross and outer. For inner joins we’ll be discussing Equi and Theta joins.Read more »
The Case statement in SQL is mostly used in a case with equality expressions. The SQL Case statement is usually inside of a Select list to alter the output. What it does is evaluates a list of conditions and returns one of the multiple possible result expressions.Read more »
When we’re developing solutions, we can sometimes forget useful commands we can use in T-SQL that make it convenient to remove data, eliminate objects, or carefully remove data. We look at three of these commands with a few examples of where we might consider using them in development, or in rare production cases. While they may offer us speed and convenience in some cases, we also look at some situations where they may not be the best tool to use.Read more »
A client recently discovered a discrepancy on one of our reports that showed an improvement in performance metrics but was inaccurate. Our reports came from a software tool, which showed the average performance throughout the day. It derived this number from periodic checks and the frequency changed, which affected our report. When we showed an improvement in the metrics on a report, the client showed us that the frequency change may have impacted this, not necessarily any improvement in performance. In situations where we’re measuring values and comparing them to other values, how can we prevent a change in measurement from impacting our reports? Read more »
Error handling overview
Error handling in SQL Server give us control over Transact-SQL code. For example when things go wrong we get a chance to do something about it and possibly make it right again. SQL Server error handling can be as simple as just logging that something happened or it could be us trying to fix an error. It can even be translating the error in SQL language because we all know how technical SQL Server error messages could get making no sense and hard to understand. Luckily we have a chance to translate those messages into something more meaningful to pass on to the users, developers, etc.Read more »
SQL Server supports table valued functions, what are functions that return data in the form of tables.
JOIN operations in SQL Server are used to join two or more tables. However, JOIN operations cannot be used to join a table with the output of a table valued function.
APPLY operators are used for this purpose.Read more »
Data conversion is one of the most fundamental tasks of any programming language. Data received from different sources is often not in the right format. For example, if you receive an XML file where age is in the string format and you want to calculate an average age for the people in the file you will need to convert age into an integer.
To make the conversion process simple, the TRY_PARSE and TRY_CONVERT functions were introduced in SQL Server 2012. Before TRY_PARSE and TRY_CONVERT, SQL Server only had the PARSE and CONVERT functions.Read more »
One of the paramount ways to guard data within a database is to utilize database encryption. However, no one encryption solution is perfect for all databases. Which encryption solution you select totally depends on the requirements of your application. Note that more powerful encryption for larger amounts of data requires a healthy amount of CPU. So, be prepared in the event that that introduction of encryption increases the system load.Read more »
Sequence objects are used to sequentially generate numeric values. They were introduced in SQL Server 2012.
Sequence objects are similar to the IDENTITY column in any SQL table. However, unlike the IDENTITY column, they are independent and are not attached to any table. Sequence objects are used both independently and within the DML statements i.e. INSERT, UPDATE and DELETE.
This article will take a detailed look at sequence objects.Read more »
This collection of content will provide an overview of SQL formatter tools, with product page links for each of the tools. If you noticed a SQL formatter tool we missed, please let us know in the comments below.Read more »
Sometimes we need to store information including photos in our database. For example, the photo of the product, the photo of the team members. But how can we store images in SQL Server?
We could create an application in .NET or Java, but if we do not have experience in those programming languages, we could use SQL Server tools to do it.
In this new article, we will learn the following tips that will help us to work with images including how to:
- insert one image into SQL Server
- store multiple files into a table
- verify that the images were inserted
SQL Server table hints are a special type of explicit command that is used to override the default behavior of the SQL Server query optimizer during the T-SQL query execution This is accomplished by enforcing a specific locking method, a specific index or query processing operation, such index seek or table scan, to be used by the SQL Server query optimizer to build the query execution plan. The table hints can be added to the FROM clause of the T-SQL query, affecting the table or the view that is referenced in the FROM clause only.Read more »
I was training some Oracle DBAs in T-SQL and they asked me how to create arrays in SQL Server.
I told them that there were no arrays in SQL Server like the ones that we have in Oracle (varray). They were disappointed and asked me how was this problem handled.
Some developers asked me the same thing. Where are the arrays in SQL Server?Read more »
One of the main tasks of a SQL Server database administrator is performance tuning. Sometimes, though, coders or developers don’t always prioritize database performance or query optimization. Here is a typical scenario
- Imagine that developers create a new table and then insert some records in a test environment and test their queries to retrieve data from it
- The query executed successfully and does not exhibit any symptoms of performance problems
- The developer team release this table and query into production
- One day you take a telephone from your colleague and he says my report is very slow
- Bingo! In production, this table contains a lot of records and this is resulting in performance bottlenecks when querying it
SQL Server provides us with two methods in T-SQL to assign a value to a previously created local SQL variable. The first method is the SET statement, the ANSI standard statement that is commonly used for variable value assignment. The second statement is the SELECT statement. In addition to its main usage to form the logic that is used to retrieve data from a database table or multiple tables in SQL Server, the SELECT statement can be used also to assign a value to a previously created local variable directly or from a variable, view or table.Read more »
An enterprise data warehouse ETL solution typically includes, amongst other steps, a data transformation step that converts source data from one data type into another. It is during this step that type conversion errors may occur and depending on the type of exception handling techniques implemented in the ETL solution (or lack thereof), frustration may occur for both ETL developers and DBAs when trying to identify and resolve type conversion errors. In this article we take a look at a trio of SQL TRY built-in functions that were introduced in SQL Server 2012, namely, TRY_PARSE, TRY_CAST, and TRY_CONVERT and how they could be utilized to reduce type conversion errors in ETL solutions and thereby saving developers needless troubleshooting exercise.Read more »
Monitoring a SQL Server database is a critical component of database administration. Ninety percent of the organizations expect the number of databases to increase over the next twelve months. An increase in data volumes can have negative effects on the availability of databases. Hence, SQL Server database monitoring is considered a critical responsibility of a database administrator. Organizations tend to spend a lot of their funds towards enterprise solutions. And due to the sensitive and growing nature of business and user needs, application availability is very important nowadays.Read more »
In an era of remote storage and retrieval of data, including the cloud, data security plays a vital role, especially since it’s vulnerable during the transit. Situations like database backup or copy from or to the cloud, there is always a risk of data exposure to outside world lurking around one corner or the other. We have seen a noticeable surge in the technologies around protection and security of data from the world full of unsafe hands. Efforts are being made to protect data at a very granular level of the encryption hierarchy. Protection of business data cannot be stressed upon more.Read more »
This article will explain how to create and configure a linked server to retrieve data from an Azure SQL database. Also, we will explain how to solve some common problems/issues during the process of creating a linked server to an Azure SQL database.Read more »
This articles gives you a performance comparison for NOT IN, SQL Not Exists, SQL LEFT JOIN and SQL EXCEPT.