database terms – Page 10

What is Entity Integrity?

January 20, 2026August 23, 2024 by Ian

When working with relational databases, data accuracy and consistency are paramount. When we talk about maintaining the integrity of the data within a relational database, several types of integrity come into play. One of the most fundamental is entity integrity.

This concept is crucial for ensuring that each record within a database table is uniquely identifiable, which in turn supports the reliability of the data. In this article, we will look into what entity integrity is, why it matters, and how it is implemented in practice. We’ll also look at an example to clarify the concept further.

Understanding INFORMATION_SCHEMA in SQL

June 28, 2023 by Ian

Behind every well-structured and organised SQL database lies a treasure trove of information called metadata. Metadata is data that provides information about other data. In relational database management systems, this metadata can typically include information like the names of databases, tables, columns, the data type of a column, access privileges, and much more.

The SQL standard provides a collection of tables/views that allow us to view metadata about the objects in the database. The SQL standard refers to this as the information schema and calls it INFORMATION_SCHEMA.

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.