The Importance of SQL Skills for Software Testers

The demand for “all-around” testers is growing...

In this blog, we will highlight the importance of good Structured Query Language (SQL) skills, specifically related to testing software. SQL is a standard computer language used to find, insert, update, and modify code data for database management. 

What does the phrase “all-around” mean? Well, it means that we need to equip Quality Assurance Engineers with the ability to test an application’s functionality. Be that, through traditional “point, click, and verify” or other testing methods. We should also be able to utilize their technical expertise to verify all aspects of a system.

How Important Are SQL Skills for a Software Tester?

You’ll find our QA Engineers are highly skilled when it comes to finding bugs and errors in applications while using testing activities. And as you will see, these developers didn’t necessarily use SQL testing in these situations as much as you might have expected. However, you’ll find their knowledge of these skills, as well as the application of these skills, has played a big part in their efficiency in solving these problems.

“… I was recently involved in front-end testing of eleven different websites. These websites hosted documents so that users might be able to print while using their personal printers. That being said, we require that our users install a special print controller on a PC before they print these documents. My job was to print documents from various combinations of operating systems, browsers, and printers. I would also verify the print quality of the documents. For this test, we did not need to apply any SQL skills. However, we did need SQL experience to verify the test data. This allows the ability to then insert, update, and delete the test data values in the database. So, I used SQL queries against the SQL server database for this particular project…”

Small Variants of This Skill Make a Big Impact

“…During a different project, I was a part of back-end testing, where complex SQL Query knowledge was a must-have. We use an internal user interface tool that gathers data from the Oracle database, which is based on the input values. And as a part of our testing, we compared the UI tool output and the database output. To do this, we inserted the same values to the tool and the database to make sure that the tool was functioning properly. The Database Administrator, then gave the testing team the specific queries with select statements to use every time input values varied. Even still, we needed to understand the relation between the tables, columns, and the query before we used it. We also used different types of SQL statements to verify the test data.

From my past experiences, I believe a tester should have the following database and SQL skills:

• The ability to recognize the different types of databases.
• The ability to connect to the database using different SQL connection clients.
• Understanding of the relationship between database tables, keys, and indices.
• Ability to write a simple select or SQL statement along with more complex join queries.
• The ability to interpret more complex queries.

SQL Statement Examples/Terms:

• Data Manipulation Language (DML): Used to retrieve, store, modify, delete, insert, and update data in the database. Examples: SELECT, UPDATE, and INSERT statements.
• Data Definition Language (DDL): Used to create and modify the structure of database objects in the database. Examples: CREATE, ALTER, and DROP statements.
• Transactional Control Language (TCL): Manages different transactions occurring within the database. Examples: COMMIT, ROLLBACK statements.

More Terms…

• Inner Join: Retrieves the matched records from both tables.
• Distinct: Retrieves the different values from one or more fields.
• In: This operator will find the value that is within the list and the value that isn’t.
• Between: This operator is used to retrieve the values within a range.
• Like: This operator will perform pattern matching using wildcards; it is used in the where clause.
• Order By Clause: Sorts the table records in ascending or descending order. The default order is ascending.
• Group By: Use Group By statements with the aggregate function to group the result set with one or more columns.
• Aggregate Functions: Performs a calculation on a set of values and return a single value. Example: Avg, Min, Max, Sum, count, etc.

Throughout my 4 years of experience with SQL, I’ve seen the benefits and usefulness of SQL Skills applied in my testing projects. I would suggest testers acquire a minimum knowledge of SQL to become the “all around,” versatile tester that clients need and value. Please reach out if you have any questions on SQL or would like to suggest future topics on this subject.