mysql - MySQL 数据读取器未进入循环

Question

我尝试了很多不同的东西，但在这一点上我很难过。

Public Function GetCust(email As String) As Integer
    Dim cs As String = <connection string>
    Dim conn As New MySqlConnection(cs)
    Dim custId As Integer
    Dim cust_query As String = "SELECT entity_id FROM customer_entity WHERE email = '@email'"
    Dim com As New MySqlCommand(cust_query, conn)
    Dim reader As MySqlDataReader

    Try
        conn.Open()
        com.Parameters.Add("@email", MySqlDbType.String)
        com.Parameters("@email").Value = email
        reader = com.ExecuteReader
        While reader.Read()
            custId = reader.GetInt16(0)
        End While
        MsgBox(custId)
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try

    Return custId
End Function

它应该只从表中提取一列和一行，所以我应该只有一个值来自查询，但它没有进入循环。对我来说似乎是语法错误，但似乎找不到。提前致谢！

Answer 1

您应该删除 SQL 字符串中电子邮件参数周围的引号：

Dim cust_query As String = "SELECT entity_id FROM customer_entity WHERE email = @email"

这将生成看起来像的 SQL

WHERE email = ''myemail@mydomain.com''

什么时候应该

WHERE email = 'myemail@mydomain.com'