Does OData specify whether filter conditions on string fields are to be evaluated case-sensitively or case-insensitively?
Example: (from the docs)
/Suppliers?$filter=Address/City eq 'Redmond'
Is this expected to be case-sensitive or not?
If I want to offer both options, how can this be expressed? There is a tolower() function that can be used like:
/Suppliers?$filter=tolower(Address/City) eq 'redmond'
or
/Suppliers?$filter=tolower(Address/City) eq tolower('Redmond')
Isn't there a more concise way to express case-insensitive matching?
The "eq" operator is supposed to be case sensitive. Usage of tolower (or toupper) is the currently recommended way of doing this.
I would expect this is depended on your database collation setting, as the odata service is just performing a query. If Vitek's answer is correct, then odata is doing some post query filtering on the result set, and that should be strange, right?
It doesn't depend on database. Even if you perform query against database in case in-sensitive way then OData will do his own additional filtering and filter your data out.
来源：https://stackoverflow.com/questions/13495905/odata-query-filter-conditions-and-case-sensitivity