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| | | The Number that shouldn't be a number This editorial was originally published on Feb 2, 2015. It is being republished as Steve is traveling. Sometimes I get really confused by the data types people choose for their tables. Take this example from one of the popular SQL forums: Why, why, why did they choose an integer for the telephone number? Sure, it's probably ultimately numeric, but does that really mean it should be an integer? Is it likely that the phone number needs to be added to something? How often do need to find the square root of a phone number? Or invert one? Is one ever likely to need to do something like this: log2(sin(TelephoneNumber2)/pi)? If so, I'd certainly love to see the reason. Telephone numbers, despite being composed of numeric digits, are not numbers. They are strings. They are not likely to be manipulated mathematically, and leading zeros are meaningful. I've seen similar strange choices with postal codes, which in South Africa are four digits long, and where leading zeros are, again, meaningful. Cape Town's postal code is 0001, not 1. Storing a postcode in a SMALLINT is possible, but not necessarily a good option. My general rule is that if the column isn't going to be mathematically manipulated, it's probably a string, not a number. I remember the pain of working with a system where a developer had chosen the TIME data type to store the number of hours worked in a day. Anyone want to figure out how you add two TIME columns together? I'll wait… I've also seen BIGINT used for the number of open orders that a customer has (optimistic), INT for dates, FLOAT for dates, NVARCHAR(MAX) for a true/false column. The list is endless. Here is my call to arms: if you're designing a table, think about the domains for each of the attributes, think about what the maximum and minimum values can be, and then think very carefully about the best data type for that attribute. And don't get fancy. For financial data, while it might be possible to convert the value into hex and store it in a Binary column, storing it in a Numeric is probably easier. Finally, what are the weirdest data type choices you've seen? Gail Shaw (Guest Editor). Gail Shaw from SQLServerCentral.comJoin the debate, and respond to today's editorial on the forums |
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| | | | | Bill Brightman from SQLServerCentral.com Use native SQL Server backups with Amazon RDS databases to easily import and export data between local server and the AWS cloud. More » |
| | Additional Articles from SimpleTalk Now that SQL Server 2019 is on the way, it’s time to start learning about the new capabilities. In this article, Greg Larson tests the new APPROX_COUNT_DISTINCT function for performance and accuracy. More » |
| | This whitepaper discusses the importance of data catalogs, the benefits they bring to businesses, and the capabilities and features required. It also outlines how data catalogs help organisations comply with data privacy regulations such as HIPAA, SOX and the GDPR More » |
| | From the SQLServerCentral Blogs - TDE and DDMSteve Jones from SQLServerCentral BlogsSomeone asked a question about TDE (Transparent Data Encryption) and DDM (Dynamic Data Masking), which are two different technologies that... More » |
| | SQLEspresso from SQLServerCentral Blogs SQL Server 2019 brings a very exciting new feature that, is long overdue. Resumable online index create is one of... More » |
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| | | Today's Question (by Kendra.Little): Which of the following is TRUE about temporary tables used in stored procedures? |
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| Yesterday's Question of the Day |
| Yesterday's Question (by Steve Jones): In Python, the range() function is used to create a list of number progressions. There are three arguments. The frist is the starting value, the second is the ending value, and last is the step progression. We can set a range like this: ctr = range(1, 10, 2) Which of these arguments are optional?
Answer: The 1st and 3rd arguments are optional Explanation: In this function, the end (2nd) argument is required. The first and third are optional. Ref: Range() - click here » Discuss this question and answer on the forums |
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| Database Pros Who Need Your Help |
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