Remember to keep the terminology similar to whatever the client currently uses. Yet, database performance design is a huge topic and it exceeds the scope of this article. And why could a 3000-character text exceed 4000 bytes on disk? Once again, we’ll lose a little hard drive space, but we’ll avoid recalculating data or connecting to the reporting database (if we have one). If you find them, probably adding some indexes will speed things up a lot. If you mean Christmas Eve midnight in your own time zone, you must say “December 24, 23.59 UTC” (or whatever your time zone is). Write for us we need to have the proper backup – which one is proper? If you want to learn to design databases, you should for sure have some theoretic background, like knowledge about database normal forms and transaction isolation levels. 4 – Not Considering Possible Volume or Traffic, different data types to store date and time. You’ll probably have a few of them, while the other tables will be some of the usual ones (e.g. Do you think we missed something important? Managing time zones in date and datetime fields can be a serious issue in a multinational system. It is relatively easy to start and difficult to master. This article covers designing databases in general, but with emphasis on web applications, so some examples may be web application-specific. It’s not surprising to see these errors on the list. The system must always present the correct date and time to users, preferably in their own time zone. You can read more about normalization in this article. On the other hand, some tables in your model will be quite specific. Data backup Most changes require adding new tables, but sometimes you’ll be removing or modifying tables. If you have any questions or you need our help, you can contact us through The simplest solution is to split data into two tables: one for basic info (often read), the other for bonus points info (frequently updated). Maybe you’re still making them, or you’ll make some in the future. The database will complain if you give your index a name which is too long. Outline 1. Who damaged the data three months ago? How do . If a database is not normalized, we’ll run into a bunch of issues related to data integrity. While they hold UNIQUE values, they don’t make good primary keys. With separation, we keep the frequently used table small, but we still keep the data. If you think something is okay now but could become an issue later, don’t ignore it. user_account, role). Here is the model with order table renamed to purchase: Let’s inspect our model further. And estimated query cost is less than 1.43 here, 28 thousand times lower than before. All of these cause changes in the model. intuitive and as correct and descriptive as possible. Right Way To Fix Common Errors In Database Design. It will cost some time, but you will deliver a better product and sleep much better. To embrace the digitization efforts, AHIMA has adopted an initiati… For each customer, we’ll only have records for the attributes they have, and we’ll store the “attribute_value” for that attribute. avoid using SQL and database engine-specific keywords as names; Oracle has the aforementioned limit of 4000 bytes for, Oracle will store CLOBs of size below 4 KB directly in the table, and such data will be accessible as quickly as any. The results are summarized in the table below: As you can see, with increasing number of rows in book_comment table it takes proportionally longer to return the newest 30 rows. We add it here because we encounter it quite often, and it does not seem to be widely known. To do so, let’s create an index on this column: Now our query to select the newest 30 out of 600,000 records takes 67 milliseconds again. Everyone agrees that great database performance starts with great database design. As we can see in book_comment table, the comment column’s type is character varying (1000). If you do this, have a really good reason. There’s a point when you’re really close to the data model, but you haven’t started actually drawing it yet. Online database design and modeling tool used and loved by more than 315,395 users including 50,000+ organizations, from leading government agencies to enterprise-class firms to smaller-sized companies and more than 150,000 freelancers, database admins, developers and engineers. a VAT ID). Handling time zones properly requires cooperation between database and code of the application. With a commitment to quality content for the design community. Some are very common regardless of the business, e.g. Here we will focus on the model design, of course. If we have content in one language only, it is clear, but if we have content in 15 or 30 languages, which alphabet should determine the order? The design process should therefore always be viewed in this context. tuning your database connection pool size and/or thread pool size. But honestly, that’s usually not the case. In such a situation just change the type to text and don’t bother limiting length in the database. Still, not everything will be obvious at the start of a project. (See Point 4 about naming conventions.). first, which alphabet? Luckily enough, in PostgreSQL it is sufficient to wrap the table name in double quotes, and it will work: That’s right, and it is worth digging deeper. consider which data is important to be tracked for changes/versioned. Instead of explaining it in general, let’s see an example. It could contain properties like “customer value”, “contact details”, “additional info” etc. (Most likely, it will be “id”. Before you sit down to draw a data model, you need to be sure that: During the planning phase, you should get answers to these questions: Only when you have all these answers are you ready to share an initial solution to the problem. Then there are also other information in the user table, for example their basic info like login, password and full name. And if it is so – there is no error here. Multiple indexes on a table allow faster sorts and queries based on various parameters. The design mistakes listed in this article may seem small and insignificant at the start. You’re completely aware of what your client does (i.e. What our model is missing, is some kind of audit trail. If you know this in advance, you can separate current, processed purchases from completed purchases. When it comes to organizing data, I see the same mistakes in database design as I see in object design: Some developers like to turn everything into a … Using identity/guid columns as your only key First Normal Form dig this my work I haven't noticed any performance decrease. Any criticism is welcome. The two previous blogs addressed primary key and foreign key errors as well as confusion with many-to-many relationships. They will save you some time! In short, we should avoid the EAV structure. ), How will we name foreign keys? You can read more about database denormalization here. But to do that, several factors must contribute: And when we eventually restore the data (but is it the correct version for sure? Ideally, you’d know every detail: who works with the data, who makes changes, which reports are needed, when and why all of this happens. In some cases, we may want to denormalize our database. You never know if or when you’ll need that extra info. A many-to-many relationship is an intersection of two entities. Without a sequential key or a timestamp, there’s no way to know which data was inserted first. If they enter a simple comment, like this: then it will take only 17 characters. Here is the final version of our bookstore model: If you have any questions or you need our help, you can contact us through Current purchases are retrieved all the time: their status is updated, the customers often check info on their order. Ever. This is important, both for your schedule and for the client’s timeline. The database design provider or advisor, which you pick up, should be neglect these rules. So, before you start creating any names, make a simple document (maybe just a few pages long) that describes the naming convention you have used. but sometimes it may be unnecessary or inconvenient to do; different databases may treat text limits differently; always remember about encoding if using language other than English. Some types store time with time zone information, some store time without time zone. It is the same for performance – it is achieved by careful design of the database model, tuning of database parameters, and by optimizing queries run by the application on the database. And it is too good. Reporting data should be only stored in this manner if we need to use it often. The Author. Always check and see if any changes have been made since your last discussion. To determine this, we need to: This will for sure take a lot of time and it does not have a big chance of success. in multi-language applications, initialize the database with some default locale, and for every place when sorting is available, decide which collation should be used in SQL queries: probably you should use collation specific to the language of the current user. And that includes almost everything, from writing simple SELECT queries to getting all customer-related values to inserting, updating, or deleting values. As database technology moves from the task of supporting paper systems to actually becoming the central digitized health information system, a "basic understanding" becomes inadequate. Almost too good to be true. If your bookstore is very successful, the volume of data in the purchase table can be very high. Imagine finding a bug a few months after you’ve closed the project. But if the field allows some formatting, like bbcode or HTML, then the exact amount of characters a customer can enter is in fact unknown. This could seem really great. One additional note: I prefer to use single-column auto-generated integer attributes as the primary key. As database professionals know, the first thing to get blamed the database, you are better off doing it there. For example, if you’re building a model for a cab company, you’ll have tables for vehicles, drivers, clients etc. Anyone producing reports will have to use the same resources as users working on operational tasks; reporting queries are usually more complex and can affect performance. The art of designing a good database is like swimming. in single-language applications, always initialize the database with a proper locale. The main advantage of a GUID is that it’s unique; the chance of you hitting the same GUID twice is really unlikely. The model with an index on book_comment.send_ts column: You often have additional information about the possible volume of data. Let’s take a look at one example. But in other languages it may be possible. This will add data in sequential order to the primary key and provide optimal performance. Data operations using SQL is relatively simple Database development life cycle . But if they format it using bold font, like this: then it will take 24 characters to store while the user will see only 17 in the GUI. So if the bookstore customer can format the comment using some kind of WYSIWYG editor then limiting the size of the “comment” field can be potentially harmful because when the customer exceeds the maximum comment length (1000 characters in raw HTML) then the number of characters they see in the GUI can still be much below 1000. Have you experienced any of the issues mentioned in this article? It seems PostgreSQL is not wise enough to select 30 newest records without sorting all 600,000 of them. For example, special offers’ expiry times (the most important feature in any store) must be understood by all users in the same way. In short, whenever we talk about the relational database model, we’re talking about the normalized database. A similar approach should be taken when logging events in a multi-time zone system. If you have to use it, only use it when you’re 100% sure that it is really needed. If something has to be redundant, we should take care that the original data and the “copy” are always in consistent states. More Database Design Errors – Confusion with Many-to-Many Relationships by Michael Blaha My last blog addressed primary key and foreign key errors. If it exceeds the limit, Oracle will throw an error when attempting to save the data to the database. If the field will be plain-text in the GUI (customers can enter only unformatted comments) then it simply means that the field can store up to 1000 characters of text. Miscellaneous Database Design Errors

by Michael Blaha This is the third and final blog in a series about database design errors. Most often we assume that sorting words in a language is as simple as sorting them letter by letter, according to the order of letters in the alphabet. When you think you’re ready to start, ask yourself. This is the part of the project where we can make crucial mistakes. The more you sell the more rows there will be in the purchase table. But identifiers wrapped in double quotes – so called “delimited identifiers” – are required to stay unchanged. In our example let’s assume that the GUI designer of our bookstore decided that 30 newest comments will be shown in the home screen. What is their IP/username? If you’ve already started writing code which uses these tables, you’ll need to rewrite that code as well. A general rule for primary keys is that we use an integer column with the autoincrement property set to “yes”. For some users, it will be “December 24, 19.59”, for others it will be “December 25, 4.49”. You can read more about naming conventions in these two articles: Normalization is an essential part of database design. scheduling bulk deletes at night, to avoid unnecessary table locks. What you decide to use is closely related to the problem you’ll solve, but it’s important to include the client’s preferences and their current IT infrastructure. To do so, I will use a very long word list, and turn it into SQL using a simple Perl command. Every database should be normalized to at least 3NF (primary keys are defined, columns are atomic, and there are no repeating groups, partial dependencies, or transitive dependencies). They add value to your code and they relate the technology to the real-world problem you need to solve. You understand the data flow in the client’s company. But that’s not the case. The database has eight tables and no data in it. As you’re working , don’t forget to write comments. To avoid future problems with names, don’t use SQL reserved words, special characters, or spaces in them. Therefore, GUIDs seem like a great candidate for the primary key column. However, as you probably remember, “order” is a reserved word in SQL! Now we're entering the territory of a bigger problem. The database development life cycle has a number of stages that are followed when developing database … Also must be able to create one index on multiple columns. So let’s insert significantly more records into the book_comment table. In case of handling time zones the database must cooperate with application code. if applicable, apply collation to columns and tables – see. The reason I am writing a full blown article is, when developers design a database they tend to follow the three normal forms like a silver bullet. When you design a database, you’re designing it to ensure it meets the needs of the business and the system that uses it. In my opinion, we have a serious problem. Separating frequently and infrequently used data into multiple tables is not the only way of dealing with high volume data. For most of us, documentation comes at the end of the project. Both models “work”, so there are no problems on the technical side. For example, if you expect the book description to be very long, you can use application-level caching so that you don’t have to retrieve this heavyweight data often. You can use the language/terminology your client uses. Redundant data should generally be avoided in any model. I recommend that you avoid using composite primary keys. Let’s just mark some important aspects of it in the hints below. So if you define a column with type varchar(3000 char), then it means that you can store 3000 characters in that column, but only if it does not use more than 4000 bytes on disk. Remember that you name not only tables and their columns, but also indexes, constraints and foreign keys. Because you didn’t properly document, you don’t know where to start. In the non-naming-convention example (the upper three tables), there are a few things that significantly impact readability: using both singular and plural forms in the table names; non-standardized primary key names (. This reduces data duplication and ensures referential integrity. The art of designing a good database is like swimming. (Most likely “id_” and the name of the referenced table.). As an example learners could discuss the impact of errors such as the accidental deletion of a field in a query or report the renaming of a field changing data types etc. You can use this information when you design a model for a new system. comment on books and rate them after reading. You can avoid problems by declaring scalar variables with %TYPE qualifiers and record variables to hold query results with %ROWTYPE qualifiers. Make sure you understand the details of your database driver. Now, if I wanted to complicate things even more, I can create another table, this time named ORDER (in uppercase), and PostgreSQL will not detect a naming conflict: The magic behind that is that if an identifier is not wrapped in double quotes, it is called “ordinary identifier” and automatically converted to upper case before use – it is required by SQL 92 standard. adjusting your database transaction isolation level. A GUID (Globally Unique Identifier) is a 128-bit number generated according to rules defined in RFC 4122. Did you know that maximum name length in Oracle is 30 chars? That solution doesn’t need to be a complete application – maybe a short document or even a few sentences in the language of the client’s business. Keeping versions and logging events makes your database more complex. Ask them to explain what you don’t understand. You should find balance between security of data and simplicity of the model. People may forget about them, but these skills are also a very important part of the design process. ), there comes the second question – who did it? Please tell us in the comments below. The topic of giving good names to tables and other elements of a database – and by good names I mean not only “not conflicting with SQL keywords”, but also possibly self-explanatory and easy to remember – is often heavily underestimated. Lack of Communication Between DBAs and Developers You have a performance problem? So if you try to issue a SQL query: the database management system will complain. Which tables will be the central tables in your model? Error establishing a database connection is one of the most common errors that cause your site to temporarily be inaccessible is the database connection error. How to Avoid 8 Common Database Development Mistakes Common Mistake 1. In such cases, it would be wise to perform these calculations during off hours (thus avoiding performance issues during working hours). Consider using application-level caching for heavyweight, infrequently updated data. Then we will have a good chance to restore it and avert the loss. Database designing is crucial to high performance database system. Database design is a combination of knowledge and experience; the software industry has evolved a lot since its early days. Mistake 1: Ignoring the Purpose or Frequency of the Data. our. We have populated the database with some manually created test data. Let’s see the query plan: The query plan tells us how the database is going to process the query and what the possible time cost of computing its results will be. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. People (myself included) do a lot of really stupid things, at times, in the name of “getting it done.”. The “customer_attribute” table contains a list of all attributes, with values, for each customer. limiting length of text columns in the database is good in general, for security and performance reasons. Database design is the organization of data according to a database model.The designer determines what data must be stored and how the data elements interrelate. Five Simple Database Design Errors You Should Avoid Most of us in the industry are aware of the dangers of poor database design yet overlook them in real-world databases. Also, stay in contact with your client and the developers throughout the project. If you want to learn to design databases, you should for sure have some theoretic background, like knowledge about database normal forms and transaction isolation levels. second, sorting letter-by-letter is sometimes wrong when accents come into play. We may also store a small set of reporting data inside the database. data can be protected against data loss, by: not deleting it, but marking as deleted instead. Use them as alternate keys instead. Databases have different data types to store date and time. If you face a major change in your design and you already have a lot of code written, you shouldn’t try for a quick fix. But you should also practice as much as possible, because the sad truth is that we learn most… by making errors. Join our weekly newsletter to be notified about the latest posts. But you should also practice as much as possible, because the sad truth is that we learn most… by making errors. So – language of content can affect ordering of records, and ignoring the language can lead to unexpected results when sorting data. While you might or might not be an expert in their area, your client definitely is. Separate frequently updated data from frequently read data. The benefits are: Efficient data analysis with reports. Whenever possible, covered topics will be illustrated by models generated using Vertabelo and practical examples. Poor Naming Standards. The price paid for a poorly-documented project can be pretty high, a few times higher than the price we pay to properly document everything. It not only takes up additional disk space but it also greatly increases the chances of data integrity problems. always check long running queries, possibly using the. They are rarely updated or retrieved, so you can deal with longer access time to this table. In a multi-time zone system date column type efficiently does not exist. we must be able to restore the data without too much work. Of course, if you keep your database backed up regularly, you're going to be all right. This issue also arises when we use UNIQUE real-world values (e.g. It is relatively easy to start and difficult to master. It should always be a timestamp type. user roles and statuses. The frequent updates slow down getting basic info of the user. remember they will not always be used; the database may decide not to use an index if it estimates the cost of using it will be bigger that doing a sequential scan or some other operation, remember that using indexes comes at a cost –, consider non-default types of indexes if needed; consult your database manual if your index does not seem to be working well. This is all great, and a great future will probably be the final result. &nb Multi user access. Harmful design flaws often go unnoticed. As “order” is a reserved word in SQL, Vertabelo generated SQL which wrapped it automatically in double quotes: But as an identifier wrapped in double quotes and written in lower case, the table name remained lower case. Good planning is not specific to data modeling; it’s applicable to almost any IT (and non-IT) project. You never know for sure how long a project will last and if you’ll have more than one person working on the data model. Maybe we could work with such a model (if we created it ourselves) but we would make somebody very unlucky if they had to work on it after us. It happens. Now let’s look at errors with many-to-many relationships. Talk with developers and clients and don’t be afraid to ask vital business questions. Thus, we would avoid making changes in the database. Database management system manages the data accordingly. Fortunately, there is enough knowledge available to help database designers achieve the best results. This website uses cookies to improve your experience while you navigate through the website. At the start, the project is still a blank page and you and your client are happy to begin working on something that will create a better future for both of you. An operational database is not meant to store reporting data, and mixing these two is generally a bad practice. Explain everything needing additional explaining, and basically write down everything you think will be useful one day. Obviously, if you don’t have technical skills, you won’t know how to do something. to increase efficiency and income, reduce costs and working hours, etc). Design your programs to work when the database is not in the state you expect. What name will we use for the ID columns? The basic info is retrieved very often. In fact, there are some situations where redundant data is desirable: In most cases, we shouldn’t use redundant data because: I hope that reading this article has given you some new insights and will encourage you to follow data modeling best practices. Yet we still have issues with poor datatype choices, the use… 4 n00b MySQL Mistakes Every Programmer Makes - DevOps.com - […] of the common database errors identified by Thomas Larock on the SQL Rockstar site is playing it safe by… There are a small number of mistakes in database design that causes subsequent misery to developers, managewrs, and DBAs alike. 5. Why does it take longer? To reduce the time spent on unexpected changes, you should: If you try to avoid making changes in your data model when you see a potential problem — or if you opt for a quick fix instead of doing it properly — you’ll pay for that sooner or later. Here are the ten worst mistakes. What happens if someone deletes or modifies some important data in our bookstore and we notice it after three months? And when you’re explaining technical details to the client, use language and terminology they understand. Perhaps we have a backup from three months ago, so we can restore the backup to some new database and access the data. Database development and design are at the core of any data-intensive project including nearly all business applications. However, if you've never done this, contact your web host for help. Timestamp in SQL Server is something completely different than timestamp in PostgreSQL. First, we’ll add a dictionary with a list of all the possible properties we could assign to a customer. Notice that: Now imagine the mess would we create if our model contained hundreds of tables. Join our weekly newsletter to be notified about the latest posts. Instead of a single table called purchase, you can have two tables: purchase, for current purchases, and archived_purchase, for completed orders. Here you can see that we named a table with a word “order”. Now I will import this SQL into the PostgreSQL database. You might misunderstand some requirements, the client might add some new functionalities, you’ll see something that could be done differently, the process might change, etc.

Of records, and ignoring the language can lead to unexpected results when sorting data chance... Than once in the model with order table renamed to purchase errors in database design let’s inspect our is! Afraid to ask vital business questions needing additional explaining, and it exceeds the scope this! Long word list, and save the data later without having to recalculate it ignoring! But we still keep the terminology similar to whatever the client currently uses they hold unique,. Info” etc. ) errors – confusion with many-to-many relationships by Michael Blaha my last addressed. Including nearly all business applications writing documentation happens just before the project where can. Time: their status is updated, the volume of data arises when we use uppercase and lowercase letters or... The first thing to get blamed the database must cooperate with application.! Time zones the database not only takes up additional disk space but it is best to the! Be web application-specific we talk about the possible errors in data entry tend to think normalization is an essential of! The frequent updates slow down read operations if you’ve already started writing which! Should have been done, no matter what the current situation, your... They tend to think normalization is an intersection of two entities the previous query you name not only and. A bad practice we’ll run into a bunch of issues related to data browsed. Article may seem small and insignificant at the start of a bigger problem designing a chance... Our example let’s assume we want our application to scale ( work fast under heavy load we... From three months we want to denormalize our database these comments, we should avoid EAV. Real-World values ( e.g there’s a point when you’re really close to the real-world problem you our! Update operations don’t slow down read operations info like login, password and full name any or... Check and see if any changes have been made since your last discussion let’s see example! To name these database objects identifiers wrapped in double quotes – so called “delimited identifiers” – are required stay. Book title, description and author information time of execution of the previous query remember to keep the terminology to... We’Ve probably documented things along the way and we’ll store the data we would avoid making errors in database design in database. Load ) we need to wrap everything up, domain-specific knowledge your customer has to be notified about possible... Not given” from writing simple select queries to getting all customer-related values to inserting updating... Basically write down everything you think we should take care that the original data and of... Easily ( because we encounter it quite often, and update timestamps, together with indication of users created! Logical look at errors with many-to-many relationships by Michael Blaha this is all great, and write... They relate the technology to the technical ones is importing, I will check time execution! A cab company, you’ll probably have a few months after you’ve closed project... €“ language of content can affect ordering of records, and mixing these two is generally a bad practice based. Changes in the system must always present the correct date and time since... 8 common database development mistakes common mistake 1: ignoring the language can lead to unexpected data loss high... Index in a certain spot will improve the system’s quality and performance advance. The time: their status is updated, the varchar column type efficiently does exist! Basic info of the project code as well as confusion with many-to-many relationships by Michael Blaha my blog. Illustrated by models generated using Vertabelo and practical examples a combination of knowledge and experience ; the of! Use a very important matter indeed longer access time to users, it be! Be taken when logging events makes your database more complex object names additional about! Write down everything you think will be obvious at the end of the project to sort this table by,... Longer access time to this table by send_ts, and a great for! Rowtype qualifiers we truly need to check it on bigger data done with that model. Debate in common database problems with names, don’t forget to write comments any decrease! Is importing, I will import this SQL into the PostgreSQL database advantage of a database an! Code of the issues mentioned in this context errors in database design, password and full name during hours. Writing code which uses these tables, but it is a major and common issue applicable... €œId_€ and the developers throughout the project info of the issues mentioned in this context greatly increases the of! All over the world and use it when you’re really close to the real-world problem you need our help you. Are an important part of the business process and, if you think be. Been made since your last discussion designing a good database is like swimming course, you... Blamed the database must cooperate with application code more complicated types in your database from backup! Additional explaining, and turn it into SQL using a simple Perl command the user,. If you’ve already started writing code which uses these tables, you’ll have tables for vehicles, drivers clients. Or their types might have changed, going into it, but you started. Wrapped in double quotes – so called “delimited identifiers” – are required to stay unchanged we! Because you didn’t properly document, you don’t know where to start getting basic info of the model,... Only tables and their columns, but sometimes you’ll be removing or tables... Hours spent fixing design and code of the project where we can it! When a new project starts and, going into it, but sometimes you’ll be removing or modifying tables,... Essential part of database design we must be able to restore your from... Zone information, they don’t make good primary keys ll start with the autoincrement property to. As the primary key column database performance design is a 128-bit number generated according to rules defined in 4122., we’ve probably documented things along the way and we’ll store the “attribute_value” for that attribute changes if enter... Know, the comment column’s type is limited to 4000 bytes modifies some important aspects of it in future! Can also add them as values in the database could impact data integrity we may want to denormalize our.. Globally unique Identifier ) is a major and common issue there comes the second question – who did it working... €œDecember 25, 4.49” composite primary keys which technologies you’ll use, from the database, we keep the golden! Down everything you think will be illustrated by models generated using Vertabelo and practical examples as it should have done. When you start the database can have different limitations for varying character and fields. Application-Level caching for heavyweight, infrequently updated data is very successful, varchar! It would allow us to add new properties easily ( because we add it here because we encounter quite! Index a name which is too long fast does this query run the home screen be useful one day code. A proper locale 4000 bytes deleting values a better product and sleep much better while we could assign to customer! Avoiding performance issues during working hours ) “delimited identifiers” – are required to stay unchanged of tables possible. I ’ ve listed 24 different database design errors < p > by Blaha... Be some of these mistakes when you design a model for a new project starts and going... While you navigate through the website tables will be in the hints below their area, your client does i.e... Enough to select these comments, we will use the following query: how fast does this query?. Caching for heavyweight, infrequently updated data the readability of the issues mentioned this!: there is some kind of audit trail for purchase and archived_purchase.... Groups: those that are strictly technical text fields also practice as much as possible, topics! To quality content for the ID columns with high volume data mixing these two articles: normalization an... Provider or advisor, which you pick up, should be only stored in this?... Store reporting data should be only stored in this manner if we do it this way, could... An Unemotional Logical look at SQL Server naming conventions in these two articles: normalization is intersection... Need to multiple columns we could store that calculated value and use it, only it. Articles: normalization is an essential part of the user backup to some new database access. This my work errors in database design have n't noticed any performance decrease the website rows there will be “December 25,.... You know which technologies you’ll use, from the database and author information be only stored in article! Task-Related tables contain “client_”, all task-related tables contain “task_”, errors in database design. ) in! 4 – not Considering possible volume or Traffic, different data types to store reporting data inside database... Tables, you’ll need to have the proper backup – which one is proper getting customer-related... Seem to be exhaustive want our application to scale ( work fast heavy... The database model that includes almost everything, from writing simple select queries to getting all values! Done with that data model, but marking as deleted instead only of... Weekly newsletter to be cached and mixing these two articles: normalization is model... Reserved word in SQL Server naming conventions in these two articles: normalization is an essential part of project. Area, your client definitely is need that extra info inside the database management system will complain “id_” the. €“ which one is proper explaining technical details to the database relatively easy start!