As a general guideline, databases are more than  mere data repositories; they are the source of rules associated with that data. 5. Well, there seem to be three, but are rows with PartIDs 1 and 2 actually the same row, duplicated? This is one of the most complex problems in current-day programming. It is annoying and simply unnecessary. While it is true that relational databases have the solid foundation of logic and set-based mathematics, the scientific rigor of the database design process also involves  aesthetics and intuition; but it includes, of course, the subjective bias of the designer as well. This system will identify a pickup/drop-off location by its ZIP code.       and  CustomerType.RelatedToColumn = ‘CustomerTypeId’ Throughout all of these data issues is the common theme that in order to have your data in the best condition possible, proper management is key. But usually, databases act as the central repositories of data and serve several applications. Or are they two different rows that should be unique but were keyed in incorrectly? He then decides to combine them all because of the similarity of their columns. When code that accesses the database is compiled into a different layer, performance tweaks cannot be made without a functional programmer’s involvement. @columnName2 sysname, If a human being could not pick which row they want from a table without knowledge of the surrogate key, then you need to reconsider your design. Now, what would make such design undesirable? I have done this topic two times before. We can play our part in dispelling this notion, by gaining deep knowledge of the system we have created and understanding its limits through testing. There are drawbacks too, because nothing is ever perfect. If the list of values is shared or reusable, at least used three or more times in the same database, then you have a very strong case to use a separate table. Stored procedures allow you to “encapsulate” any structural changes that you need to make to the database so that the knock on effect on user interfaces is minimized. This does not cover more complicated situations that procedures would cover, but can be a big help. Most of us in the industry are aware of the dangers of poor database design yet overlook them in  real-world databases. Common lookup tables have no place in sensible database design, whether used as a short-term makeshift fix or as a long-term viable solution. A well-designed database 'just works'. You could leave the single phone number in the procedure call, but store it in a different table as a stopgap measure, or even permanently if you have a “primary” number of some sort that you always want to display. Again, consistency is key. However, the amount of time to design your interface and implement it is well worth it, when all is said and done. I also presented a boiled down, ten-minute version at PASS for the Simple-Talk booth. Unless you are using dynamic SQL calls in your procedure, SQL Server can store a plan and not need to compile it every time it is executed. You may ask why it is bad to rely on the application to enforce data-integrity? If database design is done right, then the development, deployment and subsequent performance in production will give little trouble. Well, there are none. Originally there were ten, then six, and today back to ten. Exclusive arcs add greater complexity, which often lead to database development issues. A relational database maintains the integrity and consistency of data. We should be careful not to confuse splitting attributes with the logical design principle with table partitioning, a data reorganization process done at the physical level that creates smaller subsets of data from a large table or index in an attempt manage and access them efficiently. The problem is that many newcomers get seduced into applying this approach in SQL databases and the results are usually chaos. Experience tells us that, in most enterprises, applications come and go, but databases usually stand for a long time. One such model is called Entity-Attribute-Value ( or in some contexts as object-attribute-model), which is a nickname for a table that has three columns, one for the type of entity it is supposed to represent, another for a parameter or attribute or property of that entity and a third one for the actual value of that property. However, the main point of this tip is that you should avoid coding very generic objects, such as ones that take a table name and twenty column names/value pairs as a parameter and lets you update the values in the table. Just in order to change a single category,  you’ll have to consider making way for all the rows in the table regardless of whether the new column is applicable to them or not. Anith S Larson specializes in data management primarily using SQL Server. NOTE:Where this documentation is stored is largely a matter of corporate standards and/or convenience to the developer and end users. Once the major bugs are squashed, the fringe cases (which are pretty rare cases, like a user entering a negative amount for hours worked) start to raise their ugly heads. Along these same lines, resist the temptation to include “metadata” in an object’s name. These aspects of the business rule very much ought to get enforced by the database and design. This is a misunderstanding since there are no multi-valued columns here  (Pascal, 2005). Consider the following example of a table that records data about employees: Now, the EAV approach shuffles up the data, in order to  represent the attributes as values in one column and the corresponding values of those attributes in another column: Taking this to the extreme, there is no need for additional tables — all data can be crammed into a single table! If the list of values is larger than 15 or 20, you should consider a separate table. Properly compiled stored procedures can have a single compiled plan attached to it and reused. It would have been easier to start with a  single base table. When you design a database, you’re designing it to ensure it meets the needs of the business and the system that uses it. Only application-specific rules need to be implemented via the application. Numbers, I cringe in horror a name such as tblCustomer or colVarcharAddress might seem useful from a development,! 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