在第二个for循环外移动创建和添加dt_C行

 Dim nrow As DataRow = dt_diff.NewRow 
 For i =  0 至dt_diff.Columns.Count  -   1  
 val1 = dt_local.Rows（ 0 ）。项目（i）
 val2 = dt_azure.Rows（ 0 ）。项目（i）
 nrow（i）= val1  -  val2 
下一个
 dt_diff.Rows.Add（nrow）

干杯

How to insert data into datatable from the question?
Visual Studio 2015 | Console Application

I have 3 datatable named dt_A, dt_B, dt_C. I have made queries to SQL for counting table row count and fill SQLDataReader into DataTable. Involved DataTable is dt_A (grab from serverA) and dt_B (grab from serverB). While dt_C will contain a total different count from (dt_A minus dt_B).

Assuming both dt_A and dt_B should have this column:

dt_A
count_tbl1...........390 
count_tbl2.............9
count_tbl3...........500

dt_B
count_tbl1...........385 
count_tbl2.............0
count_tbl3...........480

Assume dt_C will hold differentiation from above data

dt_C
count_tbl1.............5
count_tbl2.............9
count_tbl3............20

dt_A and dt_B automatically fill on queries. dt_C will insert manually.

Dim val1, val2 As Integer
Dim colname As String
For i = 0 To dt_A.Columns.Count - 1
    colname = dt_A.Columns(i).ToString
    dt_C.Columns.Add(colname)
Next
For i = 0 To dt_C.Columns.Count - 1
    Dim nrow As DataRow = dt_C.NewRow
    val1 = dt_A.Rows(0).Item(i)
    val2 = dt_B.Rows(0).Item(i)
    nrow(i) = val1 - val2
    dt_C.Rows.Add(nrow)
Next

The second For Next, is showing wrong display. It should be adding on single row. Instead, while lopping, it will add next value to next column but next row.

I want next value to be on next column and on row(0). No any other row should be made. I have try some other but shows empty

image view here[^]

What I have tried:

Dim val1, val2 As Integer
Dim colname As String
For i = 0 To dt_A.Columns.Count - 1
colname = dt_A.Columns(i).ToString
dt_C.Columns.Add(colname)
Next
For i = 0 To dt_C.Columns.Count - 1
Dim nrow As DataRow = dt_C.NewRow
val1 = dt_A.Rows(0).Item(i)
val2 = dt_B.Rows(0).Item(i)
nrow(i) = val1 - val2
dt_C.Rows.Add(nrow)
Next

Move the creation and adding of the dt_C row outside the second for-loop

Dim nrow As DataRow = dt_diff.NewRow
For i = 0 To dt_diff.Columns.Count - 1
    val1 = dt_local.Rows(0).Item(i)
    val2 = dt_azure.Rows(0).Item(i)
    nrow(i) = val1 - val2
Next
dt_diff.Rows.Add(nrow)

Cheers