---
title: "What are insertion and deletion anomalies?"  
description: "What are insertion and deletion anomalies?"  
author: "Sumit Kesarwani"  
published: 2014-08-24  
updated: 2020-09-23  
canonical: https://www.mindstick.com/interview/1992/what-are-insertion-and-deletion-anomalies  
category: "mssql server"  
tags: ["mssql server"]  
reading_time: 2 minutes  

---

# What are insertion and deletion anomalies?

A deletion anomaly occurs when, by deleting the facts about one entity, we inadvertently delete facts about another entity; with one deletion, we lose facts about two entities. For example, if we delete the tuple for Student 001289 from a table, we may lose not only the fact that Student 001289 is in Pierce Hall, but also the fact that he has $200 left in his security deposit. An insertion anomaly happens when we encounter the restriction that we cannot insert a fact about one entity until we have an additional fact about another entity. For example, we want to store the fact that the security deposit for Pierce Hall is $300, but we cannot enter this data into the Student relation until a student registers for Pierce Hall.

## Answers

### Answer by Sumit Kesarwani

A deletion anomaly occurs when, by deleting the facts about one entity, we inadvertently delete facts about another entity; with one deletion, we lose facts about two entities. For example, if we delete the tuple for Student 001289 from a table, we may lose not only the fact that Student 001289 is in Pierce Hall, but also the fact that he has $200 left in his security deposit. An insertion anomaly happens when we encounter the restriction that we cannot insert a fact about one entity until we have an additional fact about another entity. For example, we want to store the fact that the security deposit for Pierce Hall is $300, but we cannot enter this data into the Student relation until a student registers for Pierce Hall.


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Original Source: https://www.mindstick.com/interview/1992/what-are-insertion-and-deletion-anomalies

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