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[Source] ef (lambda expression) queries several exceptions encountered in the data

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Posted on 6/13/2018 3:36:50 PM | | | |
Entities or complex types "xxxx" cannot be constructed in LINQ to Entities queries.




I am querying table A, but I only want to query some fields in table A, because some field data is not used at all, and the amount of data is too large, which greatly affects performance in both query and data transmission.

https://www.cnblogs.com/GarsonZhang/p/8760973.html  If you want to ignore querying certain fields, this article is actually the wrong solution!

Because ToList() has already queried all the data.

The correct solution is to create a new B object, select the new B object and assign a value.





LINQ to Entities does not support the specified type member "Count". Only initial value settings, entity members, and entity navigation properties are supported.




The type of my Count field isuint type, change to int typeI don't know what the specific reason is!




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