如何从 MySQL 中的一行中的列中计算值

Question

How to count all the columns in a row from a table? I'm having trouble combining of queries, I really need help. Someone help me.

My Table looks like this;

jhsf2

+-----------------------------------------+
|Stud_ID|M1|T1|W1|TH1|F1|M2|T2|W2|TH2|F2| 
|1022234|  |P |P |P  |P |A |P |P | P | P|
|1045978|  |P |P |P  |P |P |P |P | P | P|
+---------------------------------------+

And I want the result like this if I have the query to do that. I want to count from M1 to F2 that have a value not Null and it's something like this.

jhsf2

+-----------------------------------------------+
|Stud_ID|Count(M1,T1,W1,TH1,F1,M2,T2,W2,TH2,F2) |
|1022234|                  9                    |
+-----------------------------------------------+

OR I want to use WHERE query in mysql, i don't know the query but it's just like this.

Select Stud_ID,M1,T1,W1,TH1,F1,M2,T2,W2,TH2 from jhsf2 
WHERE Stud_ID = "131418100008" 
and M1,T1,W1,TH1,F1,M2,T2,W2,TH2 T2, = "P"


+-----------------------------------------------+
|Stud_ID|Count(M1,T1,W1,TH1,F1,M2,T2,W2,TH2,F)  |
|1022234|                  8                    |
+-----------------------------------------------+

Answer 1

In MySQL, you can count the values by adding up booleans:

select stud_id,
       ( (m1 = 'P') + (m2 = 'P') + . . .
       ) as cnt
from jhsf2;

Note: Having multiple columns that contain essentially an array is not a good data structure in SQL. Normally, you would want one row per stud_id and column value.

Answer 2

You can try this by checking the value not null and count of asterisk (all)

        Select count(*) from     
         jhsf2 WHERE Stud_ID !=null and M1!=null and ..
         .......

..........rest all columns which u want to check that it's values are fine or not.

Answer 3

I am not clever enough to create a select to do the job but you can do it in code. I have guessed the data type of Student ID as Long. Adjust the code if it is something else.

Private Sub GetCount()
        Dim dictStudents As New Dictionary(Of Long, Integer)
        Dim itgNonNullCount As Integer = 0
        Dim strQuery As String = "Select * from jhsf2"
        Using cn As New MySqlConnection("your connection string")
            Using cmd As New MySqlCommand With {
                    .Connection = cn,
                    .CommandType = CommandType.Text,
                    .CommandText = strQuery}
                cn.Open()
                Using dr As MySqlDataReader = cmd.ExecuteReader
                    If dr.HasRows Then
                        While dr.Read
                            'Loop through each column
                            For i As Integer = 1 To 10 'number of columns -1
                                If dr.GetValue(i) IsNot DBNull.Value Then
                                    itgNonNullCount += 1
                                End If
                            Next
                            'Add the student ID and count to the dictionary
                            dictStudents.Add(dr.GetInt64(0), itgNonNullCount)
                            'reset the count back to zero for the next record
                            itgNonNullCount = 0
                        End While
                    End If
                End Using
            End Using
        End Using
    End Sub