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REDPIXEL.PLshutterstockWith the SQL AND operator, you can implement various conditions in a WHERE query, allowing you to include or exclude different entries. In this article, we’ll explain what the operator is and the syntax for it. Using practical examples, we’ll go over how to use the operator as…
STILLFXshutterstockIt seems like almost every day a new software vulnerability is uncovered or an existing one is patched. One attack method that has long exploited such weaknesses is the SQL injection. But what exactly are these malicious database exploits, how do they work, and—most…
Large data sets can quickly get confusing! Commands like SQL SELECT TOP, LIMIT and ROWNUM allow you to limit query results to a number of your choosing. That makes results easier to read and increases efficiency and performance. In this tutorial, we show you how to use SELECT TOP…
When working with complex datasets, it’s important to be able to perform efficient, precise searches. One tool that can help with that is the logical operator OR. SQL’s OR returns records that meet at least one of two conditions. In this tutorial, we explain everything you need…
REDPIXEL.PLShutterstockWhen analysing and processing data, it’s essential to be able to select relevant records. SQL SELECT is the main tool for selecting relevant columns and records in SQL. When combined with other operators and commands, SELECT has a wide variety of potential uses. In this tutorial,…
Paolo SchorlishutterstockWhether you need to calculate total costs, sales, order quantity or any other value, SQL SUM can do a large part of that mathematical work for you! As an aggregate function that adds up all the values in a column, it is an indispensable tool in SQL. In this tutorial, we show you…
BEST-BACKGROUNDSShutterstockDuplicate rows and values in the results of a query can reduce the quality of your data analyses. You can use SQL SELECT DISTINCT to get clean, precise results. This SQL clause removes duplicate rows and includes only unique values in your results. We explain everything you need…
When querying large data sets, it helps to be able to sort your results. Luckily SQL ORDER BY does just that. It enables you to sort results in ascending or descending order based on one or more columns of your choosing. In this article, we explain how SQL ORDER BY works and…
SQL operators are at the heart of your work with SQL. They can be used to form simple or complex database queries, to compare and filter data, to make calculations and to optimise your dataset. The list of operators is long – in this article we’ll give you an overview of some of…
NULL values in datasets can lead to inaccuracies, errors and inconsistencies. That’s why SQL’s NVL function allows you to replace NULL values with more meaningful values. The result is datasets that are more accurate and easier to work with. In this tutorial, we show you how to…