By default, the String. Compare method performs culture-sensitive and case-sensitive comparisons. This method also includes several overloads that provide a culture parameter that lets you specify the culture to use, and a comparisonType parameter that lets you specify the comparison rules to use.
Calling these methods instead of the default overload removes any ambiguity about the rules used in a particular method call, and makes it clear whether a particular comparison is culture-sensitive or culture-insensitive. Both overloads of the String. CompareTo method perform culture-sensitive and case-sensitive comparisons; you cannot use this method to perform culture-insensitive comparisons. For code clarity, we recommend that you use the String.
Compare method instead. For culture-sensitive operations, specify the StringComparison. CurrentCulture or StringComparison. CurrentCultureIgnoreCase enumeration value as the comparisonType parameter. If you want to perform a culture-sensitive comparison using a designated culture other than the current culture, specify the CultureInfo object that represents that culture as the culture parameter.
The culture-insensitive string comparisons supported by the String. Compare method are either linguistic based on the sorting conventions of the invariant culture or non-linguistic based on the ordinal value of the characters in the string.
.Net Core - Foreign Key case sensitive issue in Entity Framework Core
Most culture-insensitive string comparisons are non-linguistic. For these comparisons, specify the StringComparison. Ordinal or StringComparison. OrdinalIgnoreCase enumeration value as the comparisonType parameter. For example, if a security decision such as a user name or password comparison is based on the result of a string comparison, the operation should be culture-insensitive and non-linguistic to ensure that the result is not affected by the conventions of a particular culture or language.
Use culture-insensitive linguistic string comparison if you want to handle linguistically relevant strings from multiple cultures in a consistent way. For example, if your application displays words that use multiple character sets in a list box, you might want to display words in the same order regardless of the current culture.
For culture-insensitive linguistic comparisons, the. NET Framework defines an invariant culture that is based on the linguistic conventions of English.
To perform a culture-insensitive linguistic comparison, specify StringComparison. InvariantCulture or StringComparison. InvariantCultureIgnoreCase as the comparisonType parameter. The following example performs two culture-insensitive, non-linguistic string comparisons.
The first is case-sensitive, but the second is not. You can download the Sorting Weight Tablesa set of text files that contain information on the character weights used in sorting and comparison operations for Windows operating systems, and the Default Unicode Collation Element Tablethe sort weight table for Linux and macOS.
You may also leave feedback directly on GitHub. Skip to main content. Exit focus mode. Note Both overloads of the String. Is this page helpful? Yes No.I'm having some 'tear my hair out'-problem with Entity Framework and I just can't find a solution.
What I want to do is compare strings for a search function I'm running on the server. It's basically: collection.
Contains searchTerm ; where searchTerm is a string passed by the user. However neither of these apply to my case. Here's a similar question which doesn't have an answer: Entity Framework - case insensitive Contains? Using the first alternative would result in getting every row in the database, and then perform toUpperto see if it's a match. This is unacceptable performance-wise. The second approach seems more likely to be a valid solution, but does for some reason not work.
I have two databases. One local and one remote. It's never been case sensitive for me, but I guess that is just how I set my database up. You can definitely use your first option of converting them both to upper case, EF doesn't pull them into memory to do that, just informs SQL server to do it. For example:. Question I'm having some 'tear my hair out'-problem with Entity Framework and I just can't find a solution. No matter which of these two databases I use it's still always Case Sensitive for the users.
Can someone please explain why this is happening so I can go on with my miserable life? Kind regards, Robin Dorbell. Robin Dorbell. Bulk Delete.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Have a question about this project?
Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. Equals String methods which both have the same behavior in-memory as String. Equals String, StringComparison. Actually I just got a warning about String. Equals without the third parameter not being able to be translated and being evaluated locally After upgrade to 1.
Ordinal got this error :. If this is a regression in 1. Using LOWER on indexed columns throws the index away for querying, as far as I know, which could hurt performance for people using this.
We wouldn't know this is happening since this would be translated by EF internally and would get us by surprise. Since I would have no warning about "local evaluation" on this case, I would expect that my ORM is doing the right thing and not creating a performance problem. Migrating to EFCore is becoming a show stopper for us because this issue.
Any update divega rowanmiller?
Which can optionally be turned into an error as explained in the documentation. Maybe you would add Roslyn analyzer that will display info about that in design time? Because having this warning in runtime is not an excellent experience.
Is there any plan to do this in the near future? I wasn't aware of the fact that it's not supported, saw the warning when I already used this pattern in several queries. ToLower - is string. ToLower translated correctly? Can you clarify? I would be ok with the overload with StringComparison started to throw in the default implementation in absence of client eval, but I would also be open to grandfathering it via ignoring the StringComparison argument if the general feeling is that it is preferable to mitigate the impact of the breaking change.
BalassaMarton if you control the database schema it is preferable to specify a column collation that will compare string according to your preference. It is possible but complicated. Agree with both of you.
It may not add enough value, and it can be tracked as part of supporting collations in Migrations. I just don't want us to completely dismiss the idea of allowing people to write code like this in their queries. Those arguments may be valid for the IgnoreCase comparisons but not for the rest.
This operation can even use an index if you're clever, e. Interesting, I can see how what you say could make sense using a CI index for a CS lookup, and then applying CS predicates on the results.
Here's the code I'm using:. Suchiman ah yes, I missed that part in your original sample - thanks! I can see the index being utilized now. Interesting, at least in theory SQL doesn't guarantee left-to-right evaluation and short circuiting e. So there seems to be value in providing a translation for StringComparison.
As smitpatel this would depend on collation support - seems to be the appropriate issue for tracking that added a comment there.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Have a question about this project?
Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. At the very least Oracle seems to be case-sensitive by default as well. Given that I'm popping this out a bit last minute with 2.
Like should generate LIKE - and accept that there are going to be variations across providers with this kind of thing. Hello roji. In retrospective the choice may have been a bit arbitrary, but that is correct: It is very late in the 2.
Also, changing the default later would be a breaking change, but we can certainly consider adding ways to control the behavior, e. We think it is ok to have variations across providers for this kind of thing, although it is nice to match the in-memory behavior as long as you don't need to go out of way to do so. For direct equality comparisons between strings we kind of made the opposite call: depending on the actual collation in effect, the comparison is likely to be case-insensitive in the database, but it will be case-sensitive in memory.
We made an explicit decision not to go out of our way to compensate. Neither option seemed worth pursuing and it seemed to make more sense to leave it to the application developer and the administrator of the database to control case-sensitiveness through the existing mechanisms rather than getting in the way.
I wonder if in PostgreSQL the situation is similar. OK, thanks for the doc update and the guidance. As you say, the future we can add an overload with StringComparison or something else. I guess I can recommend trying to think about this kind of thing up-front, so that we can have this kind of discussion early and possibly influence design decisions.
As an EF Core user, I personally think it's a little disappointing to find basic functionality such as LIKE varying in behavior across providers - I'd have expected EF to provide uniform behavior no matter what it is really. While having the InMemory version which may do different than provider which may unintentionally kick in while client eval is bad. But for different providers, I suppose it ok behavior.
I see the function as a way to generate query like above without falling down to raw sql. I want to call out that since apparently in PostgreSQL the SQL you write controls completely whether lookups will be case sensitive or insensitive, I don't think there are enough similarities between this decision and the way we decided to not try to force case sensitivity for SQL Server. In other words, I don't think you can use my comments at comment as guidance.
This information was taken from Oracle case insensitive searches. In versions older than 10gR2 it can't really be done and the usual approach, if you don't need accent-insensitive search, is to just UPPER both the column and the search expression. There are 3 main ways to perform a case-insensitive search in Oracle without using full-text indexes. Ultimately what method you choose is dependent on your individual circumstances; the main thing to remember is that to improve performance you must index correctly for case-insensitive searching.
In order to avoid this you can create a function-based index. This SQL Fiddle demonstrates what happens in all these queries. Note the Explain Plans, which indicate when an index is being used and when it isn't.
In order to use this as an equality operator you must specify the start and end of the string, which is denoted by the carat and the dollar sign. Be careful with this as your string may contain characters that will be interpreted differently by the regular expression engine.
You can specify a binary, case-insensitive, sort by altering the session. This will mean that every query performed in that session will perform case-insensitive parameters. To improve the performance, you can also define a linguistic index on the column for which you want linguistic comparisons. As noted in the documentation you may want to create a linguistic index to improve performance. This operator enables you to override the collation that the database would have derived for the expression using standard collation derivation rules.
If the collation name contains a space, then you must enclose the name in double quotation marks. Learn more. Case insensitive searching in Oracle Ask Question. Asked 9 years ago. Active 1 year, 5 months ago. Viewed k times. Is it possible make them case-insensitive? Lukasz Szozda k 11 11 gold badges silver badges bronze badges. Active Oldest Votes. Is there a way that i can see what the current values are so that if its persisted everywhere i can change back to original settings Case your column and your string identically.
Use regular expressions. Change it at the session level. Sepster 4, 14 14 silver badges 38 38 bronze badges. Ben Ben Does it give any advantage? V4Vendetta V4Vendetta V4Vendetta using the upper function you lose the index, do you have any idea how to make search using the index?
Lukasz Szozda Lukasz Szozda k 11 11 gold badges silver badges bronze badges.EF6 has some really cool features. I was especially interested in the ability to use custom attributes to affect migrations. In this article, I will use the example of changing whether a column is case sensitive to illustrate how to use this feature.
But there can be situations which we need to perform case sensitive search. Case sensitivity issue in EF At the moment of writing this article there is no built in feature to change collation of a column in entity framework code first approach. So if we run below test case, it will fail. We need a programmable way of changing the collation. More info about CustomDbConfiguration.
This method works even if you use auto migrations. It is also possible to create a. NET attribute and couple it to a Code First convention such that adding the attribute into a property will cause the corresponding column to be annotated. More details about Custom Code First Conventions. The main goal of this article is introduce set of new features on EF6 using an example. You can use this features as you want to transform your data access code to readable and reusable code.
Very helpful, thank you. I would suggest putting a bit more flesh into the generate alter column action i. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. RemoveRange db. SaveChanges ; db. Contain excel.
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If you change the name of the column you have to do modify the existing code and It violates the open close principle. If you need this feature for another column, you have to add a new script to change collations of those fields.
This will ended up with high density of code duplication when it comes to an enterprise level application Sometimes we delete and recreate migrations files and then the scripts that we added manually will be missed.
In development stage we normally use auto migrations. So we have to maintain those alterations inside the seed method. Table, alterColumnOperation. IsEnabled ; base.OData services behave mostly in the same way. Configuring the database collation to ignore the case is the most productive solution..NET Core vs .NET Framework - What's the difference?
Is there no possibility to alter the database, e. This article doesn't explain how to configure Entity Framework and OData Services from scratch, however there is a working example attached to this article as a Visual Studio project.
The latest version of Visual Studio NET Standard 2. NET Core 2. NET Framework 4. If you barely know the difference between. NET Standard and.
NET Core. NET Standard is a "specification" whereas. NET Core and. NET Framework are "implementations" of this specification. For further details, please visit the official Microsoft page concerning. NET Standard. Then select the " Web API " template.
Common tasks in LINQ and entity framework
It's easy to set up, it's portable and it can be used in small or even medium web sites. For using it, please install the following NuGet packages:. NET Core provides the following package:.