I'm trying to make a LINQ query on my DB SQL Server, but its result always comes 'null'. I need the first userid on which I query.
This is the way I try to query it:
public decimal GetCustomerBalance(long accountCurrentAdvisorId)
{
var result = this.Table.Select(x => x.AccountCurrentAdvisorId == accountCurrentAdvisorId);
return result;
}
You need to do this:
public decimal GetCustomerBalance(long accountCurrentAdvisorId) {
return this.Table.Where(x => x.AccountCurrentAdvisorId == accountCurrentAdvisorId)
.Select(x => x.CustomerBalance).First();
}
So you make a filter with Where , then select the information you want to get - I kicked it CustomerBalance - and finally get the first result of the generated sequence (even if it already has only one element, anyway you want an element and not a sequence containing an element, which are very different data).
The likely generated internal query will look something like this:
SELECT TOP 1 CustomerBalance FROM Table WHERE AccountCurrentAdvisorId = @accountCurrentAdvisorId
I would do so:
public decimal GetCustomerBalance(long accountCurrentAdvisorId) {
return (from table in this.Table where table.AccountCurrentAdvisorId == accountCurrentAdvisorId select table).First();
}
Null is returned because you are comparing a LONG with INT, try doing it that way.
public decimal GetCustomerBalance(int accountCurrentAdvisorId)
{
return this.Table.Where(x => x.AccountCurrentAdvisorId == accountCurrentAdvisorId)
.Select(x => x.AccountCurrentAdvisorId).FirstOrDefault();
}