Even though logically it should. Vagif Verdi Vagif Verdi 4, 1 1 gold badge 24 24 silver badges 31 31 bronze badges. The query above can be optimized a bit and it will be a bit faster.
The conceptual differences between NULL and "empty-string" are real and very important in database design, but often misunderstood and improperly applied - here's a short description of the two: NULL - means that we do NOT know what the value is, it may exist, but it may not exist, we just don't know.
Empty-String - means we know what the value is and that it is nothing. Gordon J Gordon J 1 1 silver badge 4 4 bronze badges. I would like to point out that this is not universally objective opinion. But what about other datatypes? What if we have contract, which does not have maturity date e.
It is reasonable, but so are other implementations. Sorter 8, 5 5 gold badges 55 55 silver badges 68 68 bronze badges. Kent Kent 2, 2 2 gold badges 23 23 silver badges 42 42 bronze badges. That is one interpretaion of NULL. In certain contexts, it is clearly the correct one. For example, "NULL! If it was an absence, it would make no sense, because 'x' is not equal to an absence. Why are we comparing NULL and '' in terms of space taken? Who cares!? NULL values are stored separately in a special bitmap space for all the columns.
Andriy M Andriy M 73k 16 16 gold badges 90 90 silver badges bronze badges. Community Bot 1 1 1 silver badge. Alexander Taylor Alexander Taylor Fandango68 Fandango68 3, 2 2 gold badges 34 34 silver badges 59 59 bronze badges. Peter Friis Peter Friis 17 2 2 bronze badges. I know that it is not that important. However, I would like to get it.
Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. You could add a check constraint that ensures that the string isn't empty.
Thomas - No need. Trailing spaces are ignored in string comparisons anyway. And by LEN. It does not prevent some whitespace though, like newline. Show 2 more comments.
If the value is being assigned a string property you can add logic at the property set method. If you would rather enforce this at the SQL layer then tvanfosson's answer is good. Unfortunately using a trigger is not going to work because a trigger can not affect the record being inserted Cos Callis Cos Callis 4, 3 3 gold badges 24 24 silver badges 55 55 bronze badges.
A trigger can check the field and raise an error; the cleaner solution is a check constraint, but a trigger could be made to work. Technically Keith you are correct, but I consider using a trigger in the fashion you suggest is a kludge. We agree that a check constraint is the cleanest SQL answer. Frankly, my preference is to enforce a rule like this at the object property set level so that SQL is not invoked to attempt to save an invalid object.
If you can avoid the round trip to the SQL server you are better off. IKashef, There are a lot of ways to skin this cat. I know lots of devs who prefer to enforce a rule like this at the sql layer and those like myself who prefer to handle it at code layer.
It isn't too much real work at design time to add some "IsValidToSave" logic to your object. On the other hand, at runtime not opening a connection, passing a bit stream, etc. If your data layer is expected to be shared between applications than enforcing this rule in both places maybe a good idea. Enforcing the rule in both places seems the most sensible suggestion to me.
The database constraint acts as a guard to ensure that if your IsValidToSave logic is buggy invalid data doesn't end up silently added to the database. Tejs Tejs Joel Coehoorn Joel Coehoorn k gold badges silver badges bronze badges. This got upvoted today, so it's indexed somewhere. I now know a better way to do this than the original answer. OfferText is null or listing. Patrick Harrington Patrick Harrington Anax 8, 5 5 gold badges 30 30 silver badges 66 66 bronze badges.
Adriano Carneiro Code Trawler Code Trawler 2 2 silver badges 7 7 bronze badges. Zach Johnson Zach Johnson 5 5 silver badges 12 12 bronze badges. When you say " Mansoor 12 12 bronze badges. Milan Milan 2, 1 1 gold badge 31 31 silver badges 43 43 bronze badges.
Romain Durand Romain Durand 1 1 gold badge 5 5 silver badges 20 20 bronze badges. Select Coalesce NullIf listing. OfferText, '' , NullIf company. Muhammad Sharjeel Ahsan Muhammad Sharjeel Ahsan 3 3 gold badges 13 13 silver badges 26 26 bronze badges. OfferText is null. However, the 2nd NULLIF call here serves no purpose, as if that value an empty string you're just going to coalesce back to an empty string anyway. OfferText, '' , company. Here's a solution, but I don't know if it's the best Select Coalesce Case When Len listing.
OfferText, 'company. Bo Persson Anoop Verma Anoop Verma 1, 14 14 silver badges 19 19 bronze badges. Rndm 6, 7 7 gold badges 36 36 silver badges 58 58 bronze badges. Code Crawler Code Crawler 43 5 5 bronze badges. This would be the first port of call but if you are doing things like concatenating from multiple columns in a table for example, then this would exclude the row rather than just display a blank for that column — Coops.
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