The ASIN() function in SQLite calculates the arc sine (inverse sine) of a given numeric value. The result is the angle in radians whose sine is the specified number.
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Understanding the ACOS() Function in SQLite
The ACOS() function in SQLite is used to calculate the arc cosine (inverse cosine) of a given numeric value. The result is the angle in radians whose cosine is the specified number.
Column Constraints vs Table Constraints in SQL: What’s the Difference?
In relational database management systems (RDBMSs), constraints are nifty tools that we can use to ensure the integrity, accuracy, and reliability of the data stored in our database.
Constraints can enforce rules at the column and table levels, guiding how data can be inserted, updated, or deleted. Whether you’re defining the uniqueness of a value, establishing relationships between tables, or ensuring that critical fields are never left blank, constraints play an important role in the design of relational databases.
Continue readingUnderstanding the SERIAL Type in MySQL
If you work with MySQL databases, you may have encountered the SERIAL type in a table’s definition. And if you’ve come over from PostgreSQL, you might have a false expectation about how MySQL’s SERIAL works – unless you already know 😉
Below is a quick overview of MySQL’s SERIAL type, including an explanation of how it differs from PostgreSQL’s SERIAL type and similar functionality from other DBMSs.
Understanding the Different Types of Keys in SQL
Probably the most widely known key type in SQL is the primary key, which is chosen to uniquely identify each row in a table. Perhaps next is the foreign key, which is used to establish a relationship between tables.
But there are more key types than this, and the differences between them can be subtle, but important. Here we’ll look at nine of the various key types in SQL.
Continue readingJOIN ON vs USING vs NATURAL JOIN: What’s the Difference?
Probably the most common way to join tables in SQL is with the ON clause. But that’s not the only way.
We can also join with the USING clause, which can be more concise, while providing the same or similar results. And there’s also the concept of a natural join, which is more concise again.
Let’s take a look at these three join options and compare them side by side.
Continue readingPostgreSQL \di Command Explained
The \di command can be used to list indexes in the current database when using psql (PostgreSQL’s command-line tool). This meta-command can display all indexes, or just indexes that match certain patterns. Here’s an in-depth explanation of how \di works, its options, and examples of its various uses.
7 SQL Statement Examples for Beginners
SQL (Structured Query Language) is the standard language for managing and manipulating relational databases. Whether you’re just starting your journey in data management or looking to refresh your skills, understanding the basic SQL statements is crucial.
This article will walk you through seven fundamental SQL statement examples that are pretty much standard across most major Relational Database Management Systems (RDBMSs).
Continue readingUnderstanding the Various ON DELETE Options in SQL Server Foreign Keys
It’s widely understood among SQL Server developers that foreign keys can prevent us from deleting a row from the parent table if there’s child table that references the key in that row.
But did you know that we can specify a different course of action in such cases?
For example, we could configure our foreign key to delete the child as well. Or we could set it to NULL, or to its default value.
These options are all available, thanks to the ON DELETE clause.
What is a UNIQUE Key in SQL?
In SQL, a UNIQUE key is a column or set of columns that can uniquely identify a row in a table. These are also candidate keys. Only one candidate key can become the primary key for a table. All other candidate keys can then be referred to as UNIQUE keys, given they can uniquely identify a row in a table.