Tableau & SQL – Visual Analysis
This blog post is a result of our collaboration with the University of Padua, wherein the student Prarthana Ashokmayagappa played a significant role in selecting the topic and contributing a major portion of the content.
In today’s data-driven world, SQL and Tableau have become indispensable tools for managing and visualizing data. SQL, the language for managing relational databases, allows users to extract and manipulate data, while Tableau empowers users to create interactive and insightful visualizations.
When used together, these tools enable individuals and organizations to unlock the full potential of their data, gaining valuable insights and making informed decisions.
In this blog post, we will explore the benefits of combining SQL and Tableau, showcasing how this powerful duo can help in data analysis and visualization.
What is SQL?
SQL, or Structured Query Language, is a programming language used to manage and manipulate relational databases. It is the standard language used for managing and querying data in relational database management systems (RDBMS) such as MySQL, Oracle, and Microsoft SQL Server.
SQL allows users to perform various operations on their data. The simplest use is to retrieve data from a database.
This is done using the SELECT statement, which enables the selection of specific columns from database tables.
For example, if you wanted to retrieve the details of an employees table, you would use the following query:
SELECT * FROM employees;If you wanted to select the name and salary columns from an employees table, you would use the following query:
SELECT name, salary FROM employees;SQL also allows you to add, update, and delete data in a database using the INSERT, UPDATE, and DELETE statements. These statements allow new rows to be added to a table, existing data to be modified, and data no longer needed to be removed.
One of the most powerful features of SQL is its ability to join multiple tables together. This allows you to combine data from different tables in a single query.
SQL also provides aggregate functions that allow you to summarize data in various ways, for example:
- COUNT() – number of rows
- SUM() – sum of values
- AVG() – average of values
- MAX() – maximum value
- MIN() – minimum value
SQL also provides a variety of clauses and operators to filter, sort, and group data, such as WHERE, ORDER BY, GROUP BY, etc.
With its wide range of commands and capabilities, SQL allows you to effectively and efficiently work with your data, whether you need to retrieve, update, or analyze it.
Microsoft SQL Server is a relational database management system (RDBMS) developed by Microsoft.
It is primarily used to store and retrieve data as requested by other software applications.
It is typically used in enterprise environments and supports a wide variety of data types, including structured and unstructured data.
Some of the features of SQL Server include security, scalability, and support for business intelligence (BI) and analytics. It also supports data warehousing, data mining, and analytics capabilities. It is available in a variety of editions, including Express, Standard, Enterprise, Web, and Developer, each with different levels of functionality and support.
Microsoft SQL Server is a popular choice for businesses of all sizes as it can be used for a wide range of applications such as data warehousing, online transaction processing, and data analytics. It is also commonly used for developing and deploying web, desktop, and mobile applications.
What is Tableau?
Tableau is a powerful and widely used data visualization tool and business intelligence software, that allows users to create interactive and graphical representations of data.
Data visualization involves transforming raw data (e.g. huge and complicated data sets) into a format that is easy to understand and useful for taking action.
It refers to the presentation of data through visual elements such as charts, graphs, plots, maps, and other representations, which give us visual access to large amounts of data.
Tableau’s innovation was entirely focused on Visual Analysis, which is seeing and understanding data. Visual analysis assists in making informed decisions by studying data patterns and facilitating future predictions.
Many different sectors and industries, including business, finance, healthcare, research, engineering, and government, use data visualization. It can be used for a variety of tasks, such as identifying patterns and trends in data, comparing different data sets, communicating complex data to a wide audience, supporting decision-making, and many more.
- Intuitive Platform
- Flexibility
- Interactive Visuals
- Quick Production Time
One of the major strengths of Tableau is its intuitive and user-friendly interface. Even if you have no experience with data visualization tools, you can quickly start creating meaningful visualizations of your data. The software is designed to be flexible and customizable, so one can tailor the visualizations to suit your specific needs.
Tableau offers flexibility and compatibility, enabling users to connect to their preferred data sources and extract valuable insights through visual analysis. You can connect to data stored in files such as Excel or CSV, as well as data stored in databases.
To establish these connections, Tableau utilizes data connectors, which are software components that enable Tableau to communicate and interact with specific data sources. Tableau provides native connectors for the most popular systems, allowing seamless integration and efficient data retrieval. However, for systems without native connectors, Tableau supports common ODBC (Open Database Connectivity) connectors.
This flexibility makes it easy to work with the data you already have, regardless of where it is stored.
Tableau provides a wide variety of visualizations to choose from, which includes bar charts, line graphs, scatter plots, heat maps, and more. This wide range of visualization options allows you to explore your data in different ways, which can be helpful when trying to identify new insights or patterns.
Tableau offers two modes for interacting with data: live connection and in-memory connection.
Live connection provides access to data in real-time by directly querying the data source. It is suitable for large or frequently updated datasets, ensuring up-to-date information for dynamic analysis.
Connectors control the available data infrastructure, by transferring dynamic SQL or MDX (Multidimensional Expressions) statements directly into the source database without importing all the data. This leaves the detailed data in the source system and sends the aggregate outcomes of a query to Tableau.
In-memory connection involves importing a subset or the entire data set from the data source into Tableau’s internal memory. It enables faster querying and analysis within Tableau, offering improved performance, especially when dealing with large datasets or complex calculations.
Tableau can quickly create and deploy visualizations, dashboards, or reports in a timely manner. Also, with Tableau’s sharing and collaboration features, you can easily share your visualizations and analyses with others and quickly receive feedback and suggestions. This can be especially helpful when working in teams, accelerating insights and decision-making.
To download Tableau, you can visit the Tableau website and click on the “Try Tableau for free” button. This will take you to a page where you can sign up for a free 14-day trial of Tableau Desktop. Once you have signed up, you will be able to download the Tableau software and start using it.
If you are interested in purchasing Tableau, you can also find pricing and purchase options on the Tableau website.
SQL with Tableau
In addition to the various visualization advantages that Tableau offers, it also boasts offers out-of-the-box connecting capability.
You can easily connect Tableau to a database that supports SQL, such as MySQL or Microsoft SQL Server. Once connected, you can use SQL commands to query the database and retrieve data to be used in Tableau.
You can also use Tableau’s built-in data connection features to connect to a database and retrieve data without using SQL commands.
Once you have the data in Tableau, you can use the software’s visualization tools to create interactive and informative visualizations to help you analyze and understand the data.
For Data Scientists working with SQL, this gives more benefits in terms of functionality. It offers live and efficient connectivity to SQL Server that enables us to interact with our data immediately while creating charts, reports, and dashboards.
- Connect Tableau to your SQL database. This can be done by going to the “Connect” menu in Tableau, selecting your database type (e.g. SQL Server, MySQL, etc.), and then entering the necessary connection information (e.g. server name, username, password).
- Once you are connected to the database, you can use the “SQL Query” option to write and execute SQL queries. This can be done by going to the “Data” menu, selecting the “SQL Query” option, and then entering your SQL query.
- Once the query is executed, the results will be displayed in Tableau and can be used to create visualizations. You can also use the query results to create a new data source or append it to an existing data source.
- You can also use the “SQL” button on the data connection tab and use the visual query builder to create a query using drag and drop instead of writing SQL code.
- You can now use the data in the worksheet to create visualizations and use the query to filter or aggregate data as needed.
Note that you can also use Tableau’s built-in data connection options to connect to a database and pull data into Tableau, but sometimes using SQL gives you more control over the data you want to pull and how you want to manipulate it.
There are several ways to import data from SQL Server into Tableau, depending on the version of Tableau you are using and the data connection you prefer. Below is one common method:
- Open Tableau and click on the “Connect to Data” button on the start page.
- Select “SQL Server” from the list of data sources.
- In the SQL Server connection dialog box, enter the server name and the database you want to connect to. You can also choose to sign in with your Windows or database credentials.
- Once connected, you will be prompted to select the tables or views you want to import. Select the desired tables or views and click “Connect”.
- Once the data is imported, you can start creating your visualizations and analyses in Tableau.
Alternatively, you can also use Tableau’s data extract feature to import data from SQL Server into a Tableau data extract (.tde) file, which can be used to create a faster, more efficient, and more secure connection to your data. This can be done by right-clicking on the table you want to extract, and then selecting “Extract.”
Additionally, you can also use the Tableau Data Connector SDK to create a custom data connector to SQL Server if the above methods do not suit your needs.
- Data Flexibility: Tableau allows users to connect to a variety of data sources, including SQL databases, making it easy to access and analyze data from multiple sources.
- Data Cleaning: SQL can be used to clean and prepare data before it is imported into Tableau, allowing for more accurate and meaningful visualizations.
- Real-time updates: Tableau can be connected to an SQL database, allowing users to make changes to the data and see the updates in real-time in the visualizations.
- Interactive Visualization: Tableau allows users to create interactive, graphical representations of data, making it easy to identify patterns, trends, and outliers in large sets of data.
- Collaboration: Tableau allows multiple users to access and work with the same visualizations and data, promoting collaboration and sharing of insights.
- Scalability: Tableau can handle large amounts of data and can easily scale to meet the needs of an organization.
- Flexible reporting: Tableau can be used to create a wide range of reports, from simple charts and graphs to advanced dashboards and interactive visualizations.
- Easy integration: Tableau has a wide range of connectors, which makes it easy to integrate with other systems, including SQL databases.
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This blog post is part of our collaboration with the University of Padua.
If you are a University student or professor and want to collaborate, contact us through e-mail.
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