How to count the number of trues in a table in LINQ to SQL
I have a table like this
StudID | Date | I | II | III | IV | V | VI | VII | VIII |
---|---|---|---|---|---|---|---|---|---|
100 | 2-10-11 | T | T | F | F | F | F | F | T |
101 | 2-10-11 | T | T | T | F | F | F | F | T |
100 | 3-10-11 | T | F | F | F | F | F | F | T |
100 | 4-10-11 | T | F | F | F | F | F | F | T |
Now i need to get the number of T's i.e, Trues in the table for a particular student in a particular month StudID is a varchar field Date is a datetime field and all the other datatype with bit
any ideas?
As the comments suggest, you should normalize your data.
However if you are unable to do that, you simply need to count the number of trues in each row.
context.Studs.Sum(s => (s.I ? 1 : 0) + (s.II ? 1 : 0) + ... + (s.VIII ? 1 : 0));
edit: To restrict the sum based on StudID and the month, you would use a Where
operator
var id = "100";
var month = 10;
var set = context.Studs.Where(s => s.StudID == id;
set = set.Where(s => s.Date.Month == month);
return set.Sum(s => (s.I ? 1 : 0) + (s.II ? 1 : 0) + ... + (s.VIII ? 1 : 0));
var numberOfTrues = context.Students.
Where(x => x.StudID == 123 && x.Date.Month == studentMonth).
Sum(x => x.I.ToInt() + x.II.ToInt() + ... + x.VIII.ToInt());
// Add extension method
public static int ToInt(this bool value)
{
return value ? 1 : 0;
}
If the T and F actually are characters and not bit/booleans then you could try
context.Studs.Sum(s => (s.I+s.II+s.III+s.IV).Count(c => c=='T') );
but I wonder what the generated SQL will look like. Problably not something like
SELECT SUM(LEN(REPLACE(I+II+III+IV, 'F', '')))
var student = context.Students.Where(s => s.StudID == id && s.Date.Month == month).Single();
var trues = from results in student.GetType().GetProperties().Where(p => p.PropertyType == typeof(bool))
let val = (bool)f.GetValue(student, null)
where val
select val;
// You can now check trues.Count()
Build a function called something like bool CheckBit(StudID, Date, num) where you pass in the StudID, Date, and a number from 1 to 8. Put the function call in a loop and pass in 1 - 8 and keep a count of how many times you return true
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