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LinQ expression not supported in the Where clause
My code accesses a SQL Server database using DevExpress XPO. It contains the following query:
var relevantAccount = accounts
.Where(acc => String.Compare(acc.Description, "Some Account Name", true) == 0)
.FirstOrDefault()
;
I use String.Compare rather than == so I can do a case-insensitive comparison. It compiles, but throws an Exception during runtime:
System.NotSupportedException: 'The expression is not supported in the Where clause: Compare(acc.Description, "Some Account Name", True)'
Why does this Where clause throw an Exception, and how do I fix it?
1 answer
The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| FractionalRadix | (no comment) | Mar 4, 2026 at 10:46 |
Since the program uses XPO, the system tries to translate this query to SQL. However, the LinQ provider (LinQ-to-XPO) does not support String.Compare. You'd likely have the same problem with other LinQ providers.
It does support ToLower() so a simple solution is:
var relevantAccount = accounts
.Where(acc => acc.Description.ToLower() == "some account name")
.FirstOrDefault()
;
For more complex expressions, it may be necessary to force evaluation in memory using AsEnumerable():
var relevantAccount = accounts
.AsEnumerable()
.Where(acc => ... complex expression over acc... )
.FirstOrDefault()
;
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