如何在vb.net中进行具有计数，不同，位置，喜欢，子句的查询

Question

    Dim cn As New OleDbConnection(My.Settings.connection)
    Dim SQLResult As Object
    Dim SQL As New OleDbCommand
    cn.Open()
    SQL.Connection = cn
    SQL.CommandText = "SELECT COUNT(*) FROM (SELECT DISTINCT StudentNumber FROM StudentTable)"
    SQLResult = SQL.ExecuteScalar
    MsgBox(SQLResult)

    cn.Close()

我想添加此WHERE节，例如'％“ + StudentNumberTextBox.Text +”％“

Answer 1

我使用表格适配器

SELECT        COUNT(*)
FROM            (SELECT DISTINCT StudentNumber FROM PresentStudentTable
WHERE        (StudentNumber = ?))

在表单代码上

TableTableAdapter.NameOfQuery(StudentNumberTextBox.Text)