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What is a Database Transaction?

November 11, 2025October 19, 2025 by Ian

A database transaction is a sequence of operations performed as a single logical unit of work. The key idea is that all the operations in a transaction either complete successfully together or fail completely. There’s no in-between. This ensures the database remains consistent even if something goes wrong, like a power outage or a failed query.

In simpler terms, a transaction lets you group multiple SQL statements into one reliable operation. If everything runs smoothly, you commit the changes. If not, you roll back the entire transaction, leaving the database exactly as it was before it started.

What is CRUD?

March 4, 2023 by Ian

In the world of database management systems (DBMSs) and computer programming, CRUD is an acronym that stands for Create, Read, Update, and Delete. These are considered to be the four basic operations of persistent storage.

Let’s take a look at how CRUD fits into database management systems and programming in general.

What is TCL?

November 11, 2025February 21, 2023 by Ian

When using relational database management systems (RDBMSs) we often hear terms like DDL, DML, DQL, DCL, and TCL. But what exactly are they?

In this article we’ll look at what TCL stands for in the context of SQL, and what it does.

What is DCL?

February 21, 2023February 19, 2023 by Ian

When using relational database management systems (RDBMSs) we often hear terms like DDL, DML, DQL, TCL, and DCL. But what exactly are they?

In this article we’ll look at what DCL stands for in the context of SQL, and what it does.

What is DQL?

February 21, 2023February 18, 2023 by Ian

We often hear terms like DDL, DML, DQL, TCL, and DCL when using relational database management systems (RDBMSs). But what exactly are they?

In this article we’ll look at what DQL stands for, and what it does.

What is DML?

February 21, 2023February 17, 2023 by Ian

We often hear terms like DDL, DML, DQL, and DCL when using relational database management systems (RDBMSs). But what exactly are they?

In this article we’ll look at what DML stands for, and what it does.

What is DDL?

February 21, 2023February 16, 2023 by Ian

We often encounter terms like DDL, DML, DQL, DCL, and TCL when using relational database management systems (RDBMSs). But what do they mean?

In this article we’ll look at what DDL stands for and what it does.

Signed vs Unsigned Integers

February 14, 2023February 9, 2023 by Ian

The integer data type is probably one of the more common data types when working with database management systems (and with computing in general). The integer is a numeric data type that allows us to store certain kinds of numbers.

More specifically, an integer is the number zero (0), a positive natural number (e.g. 1, 2, 3, …) or a negative integer with a minus sign (e.g. −1, −2, −3, …). Integers contain no decimal or fractional part.

However, many computing environments distinguish between signed integers and unsigned integers.

Let’s take a look at the difference between signed integers and unsigned integers.

What is a Comparison Operator?

February 14, 2023September 26, 2020 by Ian

Comparison operators are an important part of most programming languages.

Comparison operators are used to compare two expressions. The result is either true or false. It could also be unknown. This could also be represented by either 1, 0, or NULL, depending on the language. These are typically known as “Boolean expressions”.

When used with databases, comparison operators can be used inside your SQL queries to filter data to a certain criteria.

What is a CHECK Constraint?

February 10, 2026May 27, 2020 by Ian

In database terms, a CHECK constraint is a type of constraint that checks data before it enters the database.

CHECK constraints help maintain data integrity, because they prevent invalid data entering the database.