如何通过命令提示符将整数插入数据库

Question

I am trying to insert a integer into a database in C# using the code below, but everytime I run the compiler informs me that my integer is not a valid column "Invalid Column Name UserID"

Does anyone have any insight on this? Thanks.

Console.WriteLine("Please enter a new User Id");
        string line = Console.ReadLine();
        int UserID;
        if (int.TryParse(line, out UserID))
        {
            Console.WriteLine(UserID);
            Console.ReadLine();
        }



        //Prepare the command string
        string insertString = @"INSERT INTO tb_User(ID,f_Name, l_Name) VALUES (UserID,'Ted','Turner')";

Answer 1

First things first, I would get into the habit of using parameterised queries, if you are not planning to use stored procedures. In your example, I would:

using (var command = new SqlCommand("INSERT INTO tb_User(ID, f_Name, l_Name) VALUES (@id, @forename, @surname)", conn))
{
  command.Parameters.AddWithValue("id", id);
  command.Parameters.AddWithValue("forename", forename);
  command.Parameters.AddWithValue("surname", surname);

  command.ExecuteNonQuery();
}

Where id , forename , surname are the appropriate variables. Notice I am also using using blocks, this ensures that my objects are cleaned up after it has completed.

Answer 2

it is because the 'UserID' within your insertString : ..."VALUES (UserID"... is invalid.

you need to pass a value for the UserID such as: ..."VALUES ('myUserIDGoesHere'"...

Answer 3

Your string is not dynamically reading the variables. Use something like this:

string insertString = string.Format(@"INSERT INTO tb_User(ID,f_Name, l_Name) VALUES ({0},'{1}','{2}')", UserId, "Ted", "Turner");

There are better ways depending on what kind of data access you're using, but this is just to make the point of how to correct the string.

Answer 4

To answer your question regardless of your approach, try:

string insertString = @"INSERT INTO tb_User(ID,f_Name, l_Name) VALUES ("
+ UserID + ",'Ted','Turner')";

Answer 5

The problem is the first argument in VALUES - it simply isn't defined. If this is meant to be the value the user has entered, then you need to add a parameter to the command and use that parameter in the SQL; for example:

cmd.Parameters.AddWithValue("@id", UserID);

An then use

VALUES(@id, ...

in the TSQL.

Also, generally you might want to have the system generate the unique id. A the simplest level this could have an IDENTITY defined (an automatic sequence).

Answer 6

Use a parameterized query:

using (var connection = new SqlConnection(connectionString))
{
    connection.Open();

    using (var insertCommand = new SqlCommand(
        @"INSERT INTO tb_User (ID, f_Name, l_Name)
          VALUES (@ID, 'Ted', 'Turner')", connection))
    {
        insertCommand.Parameters.AddWithValue("@ID", userID);
        insertCommand.ExecuteNonQuery();
    }
}