SQL

Introduction to Indexing in SQL

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When working with databases, performance can be very important. This is especially true in production environments where the end users expect their queries and reports to be generated within seconds (or even milliseconds).

While blistering fast queries may be the norm with smaller datasets, as our databases grow larger and more complex, it can become much more of a challenge to keep our queries nice and snappy. When working with smaller datasets, it’s often possible to get lightning speed results even when not optimizing for speed. But as the datasets grow larger, we need more efficient tools and techniques to retrieve and manipulate data. One such tool is the index.

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SQL for Beginners: 10 Must-Know Concepts to Kickstart Your Database Journey

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SQL stands for Structured Query Language. It’s the go-to query language for most of us who develop relational databases. If you want to work with relational database management systems, learning SQL is pretty much non-negotiable. Especially if you want to become a SQL developer.

If you’re interested in becoming a SQL developer, here are ten essential SQL concepts that you need to learn.

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Introduction to the Enum Data Type in SQL

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The Enum (enumeration) data type in SQL is a specialised string object that allows us to define a list of predefined values for a column. This data type can be particularly useful when we want to restrict the possible values that can be stored in a specific column to a fixed set of options.

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Understanding the SQL Subquery

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One of the things I love about SQL is just how easy it is to write a simple query that returns a meaningful result set, without having to a whole bunch of complex code. And I imagine most beginners are relieved when they discover this too.

However, while basic queries can go a long way, there’s a whole world of advanced techniques that can take our SQL development to another level. Somewhere in that world, would be the SQL subquery.

In this article, we look at the SQL subquery. We’ll explore what subqueries are, how they work, and when to use them. We’ll also look at some simple examples to demonstrate their use.

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SQL Truncate Explained

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In SQL databases, the TRUNCATE statement can be used to quickly remove all data from a table. Unlike the DELETE statement, TRUNCATE is typically faster and uses fewer system resources, especially for large tables.

In this article, we’ll explore the TRUNCATE statement, its usage, and provide some examples.

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How to Return Values in SQL Without using SELECT

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The SQL SELECT statement is possibly the most commonly used SQL statement. It’s often used to return data from a database, but it can also be used to call functions that return data. The SELECT statement can also be used to return static values, such as string literals.

But the SELECT statement isn’t the only way we can return data in SQL. Another way to return values is with the VALUES statement.

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What is a Composite Primary Key?

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Primary keys are a crucial part of relational database management systems (RDBMSs). Most of the time we create a primary key constraint against a single column that is the unique identifier for the table.

But we can also create primary key constraints against more than one column. When we do this, we call it a composite primary key.

Composite keys can be handy when we don’t have a single column that contains unique values, but multiple columns can be combined to create a unique value.

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SQL Set Operations Explained

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Most of the major RDBMSs provide us with the ability to perform set operations.

A set operation is one that combines the results of multiple query blocks into one. For example, we could combine the result of two separate SELECT statements. The results are displayed in a single result set as though we’d run a single query.

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