WPF C# LINQ: Operator '&&' cannot be applied to operands of type 'string' and 'string' query

Question

I'm trying to execute this query but for some reason it doesn't like the fact that 2 strings are sitting beside each other, here's the query:

var FiveSecStatsQuery = from qai in connection.QuickAnalyzerInputs
                             join calP in connection.CalculatedPrices on qai.InputID equals calP.TradeID
                             where ***(qai.ClientName = clientName) && (qai.CurrencyPair = cur_pair)*** 
                             && (calP.Description = PriceDescriptions.FiveSeconds) && (calP.Outcome != null)
                             select new
                             {
                                 calP.Outcome
                             };

The error is : Operator '&&' cannot be applied to operands of type 'string' and 'string'

Why is it giving me this error? Both ClientName and CurrencyPair are of type string in the database. The error occurs where the asterisks are

Solution 1

You need double ==, not single = so your where clause should be:

where (qai.ClientName == clientName) && (qai.CurrencyPair == cur_pair)
&& (calP.Description == PriceDescriptions.FiveSeconds) && (calP.Outcome != null)

Solution 2

Change (qai.ClientName = clientName) && (qai.CurrencyPair = cur_pair) to (qai.ClientName == clientName) && (qai.CurrencyPair == cur_pair) since its boolean operation not value assignment

Comments

[kknaguib]

Wowww! thanks been staring at it for 15 min and I couldn't see that. Thanks again @Habib!

[Moeez]

Where(m=> (m.zdjh == msn).ToString() && (dt >= m.sjsj).ToString() this is my LINQ exp and I am getting operator && cannot be applied to operands of type 'string' and 'string' c#