Ensuring Data Reliability: The Role of Physical Integrity in Database Management

Posted on by Ian

Maintaining the reliability, accuracy, and consistency of data is paramount when dealing with databases. One important factor that plays a huge role in ensuring these qualities is the concept of physical integrity.

While much attention is given to logical integrity—ensuring the data follows the rules of the schema and maintains meaningful relationships—physical integrity is equally important. It deals with the actual storage of data and the correct functioning of the hardware and software systems that store and manage this data.

This article delves into what physical integrity is in the context of database management, why it is important, how it can be compromised, as well as best practices for maintaining it.

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Using ON UPDATE SET DEFAULT in SQL Server

Posted on by Ian

In SQL Server, foreign keys are essential for maintaining referential integrity between tables. When creating foreign keys, we have a number options available to us when it comes to defining what should happen in the event that the related data in the parent table changes. One such option is ON UPDATE SET DEFAULT.

This article will explain what this option does, provide an example of its usage, and offer a practical scenario where this feature can be useful.

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Fix “The correlation name … is specified multiple times in a FROM clause” in SQL Server (Error 1011)

Posted on by Ian

If you’re getting an error that reads something like “The correlation name ‘a’ is specified multiple times in a FROM clause’” in SQL Server, it could be that you’re doing a join on two tables, but you’re assigning them the same aliases.

Each table’s alias must be unique.

To fix this issue, be sure to use unique table aliases in your query.

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Indexes on Expressions in PostgreSQL: A Quick Overview

Posted on by Ian

In PostgreSQL, indexes on expressions (also known as “functional indexes”) allow you to create an index not just on a column but on the result of an expression or function applied to a column (or multiple columns). This can significantly improve query performance when the same expression is used frequently in queries, especially for complex calculations or transformations.

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Fix “Cannot create index on view because the view is not schema bound” in SQL Server (Error 1939)

Posted on by Ian

If you’re getting an error that reads something like “Cannot create index on view ‘MyView’ because the view is not schema bound” in SQL Server, it sounds like you’re trying to create an index on a view that’s not schema bound.

Indexes can only be created on schema bound views.

To fix this issue, define the view as schema bound before creating the index.

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Prepared Statements in PostgreSQL: A Complete Guide

Posted on by Ian

Prepared statements are a feature in PostgreSQL that can improve performance and security when executing repetitive SQL queries.

By creating a prepared statement, the server can parse and plan the query once and reuse it multiple times, leading to faster execution. Prepared statements also help in preventing SQL injection attacks by safely handling user input.

In this article, we’ll explore prepared statements in PostgreSQL, discuss how to create and use them, and cover other important considerations such as query planning and cleaning up statements.

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3 Quick Examples of SQL Subqueries in the WHERE Clause

Posted on by Ian

SQL subqueries are like little helpers that fetch data for our main query. They’re super handy when we need to filter our results based on some other data in our database.

Probably the most common placement of a subquery in SQL is in the WHERE clause. Placing a subquery in the WHERE clause allows us to compare a column against a set of rows that match a certain criteria.

Let’s look at three quick examples of subqueries in the WHERE clause.

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Fix “Computed column … cannot be persisted because the column is non-deterministic” in SQL Server (Error 4936)

Posted on by Ian

If you’re getting an error that reads something like “Computed column ‘c3’ in table ‘t1’ cannot be persisted because the column is non-deterministic” in SQL Server, it appears that you’re trying to persist a computed column that’s nondeterministic.

A nondeterministic function or expression returns a different result for the same input. If a column uses such an expression, then it will be nondeterministic. A computed column must be deterministic.

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Understanding Partial Indexes in PostgreSQL

Posted on by Ian

Adding indexes to a table is a well established practice for speeding up regular queries in relational databases such as PostgreSQL. While they can do wonders for query performance, indexes can also take up a lot of disk space.

Today we’re going to be looking at a particular type of index that can help reduce the impact on disk space, and query performance – the partial index.

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