How to execute stored procedure multiple times in C#

问题

I have a time sheet app where users enter their time in/out for different days of the week. The form processes the in/out from each day, stuff them as parameters into a stored procedure and add them to the database. How would I accomplish this most efficiently? I don't have access to the DB, just the stored procedures.

This is the bare code behind, I've stripped out some unnecessary codes.

SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand cmd = new SqlCommand("insertINOUT", conn);
cmd.CommandType = CommandType.StoredProcedure;

cmd.Parameters.Add(new SqlParameter("@UserName", user));

for (int j = 0; j < weekDays.Length; j++)
{
    cmd.Parameters.Add(new SqlParameter("@In", in));
    cmd.Parameters.Add(new SqlParameter("@Out", out));
    cmd.ExecuteReader();
}
conn.Close();

The code works if there's only 1 day of in/out. If the users fill out multiple days, I'll get this error: Parameter '@In' was supplied multiple times.

Thanks for your help.

回答1:

SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand cmd = new SqlCommand("insertINOUT", conn);
cmd.CommandType = CommandType.StoredProcedure;

for (int j = 0; j < weekDays.Length; j++)
{
    **cmd.Parameters.Clear();**
    cmd.Parameters.Add(new SqlParameter("@UserName", user));
    cmd.Parameters.Add(new SqlParameter("@In", in));
    cmd.Parameters.Add(new SqlParameter("@Out", out));
    cmd.ExecuteReader();
}
conn.Close();

(You have to clear the parameters each iteration.)

回答2:

Another alternative, you could change the scope of the SqlCommand so that it is recreated each time.

SqlConnection conn = new SqlConnection(connString);
conn.Open();

for (int j = 0; j < weekDays.Length; j++)
{
    SqlCommand cmd = new SqlCommand("insertINOUT", conn);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.Add(new SqlParameter("@UserName", user));
    cmd.Parameters.Add(new SqlParameter("@In", in));
    cmd.Parameters.Add(new SqlParameter("@Out", out));
    cmd.ExecuteReader();
}
conn.Close();

Seems a bit wasteful, but there are some libraries that work this way (the Enterprise Library DAAB comes to mind).

回答3:

using (SqlConnection conn ... )
{
    SqlCommand cmd = ...
    ...
    // Set up the parameter list.
    //   You can use   .AddWithValue   here to add values that don't change in the loop.
    cmd.Parameters.Add("@Username", SqlDbType.VarChar);
    ...
    for (...)
    {
        // Load one set of loopy values.
        cmd.Parameters["@UserId"].Value = user;
        ...
    }
}

回答4:

The reason you are getting that error is because the for loop is re-adding the parameter multiple times:

cmd.Parameters.Add(new SqlParameter("@In", in));
cmd.Parameters.Add(new SqlParameter("@Out", out));

The proper way to do this is either clear the Parameters collection at the last line of the foor loop or simply check if the parameter already exists and set its value instead of doing Parameters.Add

回答5:

SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand cmd = new SqlCommand("insertINOUT", conn);

    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.Add(new SqlParameter("@UserName", user));
    for (int j = 0; j < weekDays.Length; j++)
    {


        cmd.Parameters.Add(new SqlParameter("@In"+j, in));
        cmd.Parameters.Add(new SqlParameter("@Out"+j, out));
        cmd.ExecuteReader();
    }
    conn.Close();

来源：https://stackoverflow.com/questions/7395445/how-to-execute-stored-procedure-multiple-times-in-c-sharp

标签

procedures