mysql - 使用 VB.net 以编程方式限制 mysql 数据库的行数

Question

美好的一天，我编写了一个函数，需要限制可以添加到数据库的员工数量。

    <WebMethod()>
Public Function EmployeeSubToken()
    Dim cmd As New SqlCommand("Select vchSubscriptionType FROM BillingInfo", con)
    Dim subtype = "vchSubscriptionType"
    Dim Token


    Select Case subtype
        Case subtype = "Bronze"
            Token = 1
        Case subtype = "Silver"
            Token = 2
        Case subtype = "Gold"
            Token = 3
        Case subtype = "Platinum"
            Token = 4
    End Select

    Dim cmd2

    Select Case Token
        Case Token = 1
            cmd2 = New SqlCommand("SELECT * FROM Subscribers.dtEmployment Where ROWNUM <= 5 LIMIT 5")
        Case Token = 2
            cmd2 = New SqlCommand("SELECT * FROM Subscribers.dtEmployment Where ROWNUM <= 5 LIMIT 10")
        Case Token = 3
            cmd2 = New SqlCommand("SELECT * FROM Subscribers.dtEmployment Where ROWNUM <= 5 LIMIT 25")
        Case Token = 4
            cmd2 = New SqlCommand("SELECT * FROM Subscribers.dtEmployment")
    End Select

End Function

有谁知道这是正确的做法吗？如果不是我将如何实现这一点？

Answer 1

如果您想限制插入，请使用一个函数来查询数据库并返回行数，SELECT COUNT(*) FROM dtEmployment ;然后只需使用一个简单的 if，

if(dtEmploymentCount < MydesiredCount) then
'Do My Insert

else
'Return your message (Maximum amount of entries reached)
end If