Question

我有这个表，我将其命名为Users，每当用户使用注册表单时，我想向Users.table插入他输入的所有凭据。问题是，不知何故，数据库正在尝试将用户名（列）从varchar转换为int。这是我的插入查询：

string Query = "Insert into Users(FirstName, LastName, Username,
                Password, Role, Email, Class) values('" + txtfn.Text + "',
                '" + txtsn.Text + "','" + txtUsername.Text + "','" + txtPassword.Text + "',
                '" + cbRole.Text + "','" + txtEmail.Text + "','" + cbClass.Text + "')";

The error that pops-ups everytime a user is trying to sign up

如何防止此转换发生或以其他方式处理此错误？在此先感谢。

Answer 1

以下是如何使用SQL参数并指定类型。哪个更安全，更精确，还可以处理某些类型的转换（例如DateTime）：

string Query = "Insert into Users(FirstName, LastName, Username, "
            + " Password, Role, Email, Class) "
            + " values(@fn, @sm, @user, @ps, @role, @email, @class)";

SqlCommand sqlcom = new SqlCommand(Query, sqlconnection);

// change the types to match SQL Column data types
// I set all as Nvarchar as a sample
var fnParma = new SqlParameter("@fn", SqlDbType.NVarChar);
var smParma = new SqlParameter("@sm", SqlDbType.NVarChar);
var userParma = new SqlParameter("@user", SqlDbType.NVarChar);
var psParma = new SqlParameter("@ps", SqlDbType.NVarChar);
var roleParma = new SqlParameter("@role", SqlDbType.NVarChar);
var emailParma = new SqlParameter("@email", SqlDbType.NVarChar);
var classParma = new SqlParameter("@class", SqlDbType.NVarChar);

// Here set each value by converting it to the specified type.

fnParma.Value = txtfn.Text;
smParma.Value = txtsn.Text;
// Continue for all the params. If you have int column use Int32.Parse(Text);

sqlcom.ExecuteNonQuery();

Answer 2

sql表中的username列需要整数，这里传递字符串。因此，请将表中的username列数据类型更改为varchar。它会工作正常。希望很清楚。

我插入到sql表时将varchar转换为int

2 个答案: