What is a Surrogate Key in SQL?

In SQL and relational database design in general, an important concept is the identification of unique rows in a table. A surrogate key is one method for achieving this.

Understanding what surrogate keys are, and how they differ from natural keys, is crucial for database administrators, developers, and anyone involved in data modeling or management.

In this article we’ll explore what the surrogate key is, how it differs from the natural key, and examples of implementing it in SQL.

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What is a Superkey Key in SQL?

There are various key types in SQL, each with their own characteristics. Some of these can be enforced with a constraint of one kind or another. Others are not necessarily enforced with a constraint, but are more of an abstract notion, albeit, an important one. These key types consist of one or more columns with certain characteristics that qualify it as the particular key.

One such key type is the superkey.

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What is a Trigger in SQL?

In SQL databases, triggers can play a significant role in automating responses to specific events within a database. Whether we’re dealing with data validation, logging changes, or enforcing business rules, SQL triggers can be a handy tool to ensure that certain actions are taken automatically when certain conditions are met.

This article covers what SQL triggers are, how they work, and provides an example to illustrate their use.

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What is a Natural Key in SQL?

In relational database design, the concept of a “key” is fundamental. Keys are essential for uniquely identifying records in a table, ensuring data integrity, and facilitating efficient data retrieval. Among the different types of keys used in SQL, the natural key is one that often sparks discussion among database designers, especially when compared with the surrogate key.

Let’s explore the concept of a natural key, its advantages and disadvantages, and look at a practical example to illustrate its use.

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What is Domain Integrity?

Domain integrity is an important concept in relational database management that ensures the accuracy, validity, and consistency of data within a database. It refers to the enforcement of rules and constraints that ensure data entered into a database adheres to a predefined set of acceptable values. This helps maintain the quality of data and prevents the entry of erroneous, incomplete, or invalid data into the system.

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What is Entity Integrity?

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 delve 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.

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What is the Year 2038 Problem?

The Year 2038 problem (also referred to as the Y2K38 bug) refers to a problem that some computer systems might encounter when dealing with times past 2038-01-19 03:14:07.

Many computer systems, such as Unix and Unix-based systems, don’t calculate time using the Gregorian calendar. They calculate time as the number of seconds since 1 January 1970. Therefore, in these systems, time is represented as a big number (i.e. the number of seconds passed since 1970-01-01 00:00:00). This is typically referred to as Epoch time, Unix time, Unix Epoch time, or POSIX time. As I write this, Unix time is 1560913841. And as I write this next line, Unix time has incremented to 1560913879.

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What is Normalization?

Normalization is the process of organizing a database to reduce redundancy and improve data integrity.

Normalization also simplifies the database design so that it achieves the optimal structure composed of atomic elements (i.e. elements that cannot be broken down into smaller parts).

Also referred to as database normalization or data normalization, normalization is an important part of relational database design, as it helps with the speed, accuracy, and efficiency of the database.

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