using string[] to multi-query in a loop

Question

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Hello,

I would like to use string[] to query in a loop.

my idea is: keep my information in string[] and place in query string,specify with index

here is my code

C#

string[] edit_list = txtReqList.Text.Split('\n');
string query ;
MySqlCommand cmd = new MySqlCommand();
for (int i = 0; i < edit_list.Length; i++)
{
    try
    {
        query = "UPDATE submit
                 SET submit_status ='S'
                 WHERE submit_id = '" + edit_list[i] + "'";
        //Open connection
        if (this.OpenConnection() == true)
        {
            //Assign the query using CommandText
            cmd.CommandText = query;
            //Assign the connection using Connection
            cmd.Connection = connection;
            //Execute query
            cmd.ExecuteNonQuery();

        }
    }
    catch (MySqlException ex)
    {
        MessageBox.Show(ex.ToString());
    }
    this.CloseConnection();
}

Unfortunately, the only last index is queried, e.g.

my string[] are : 0,1,2,3.

following from my idea, it should update at submit_id = 0,1,2 and 3
but, it update only submit_id = 3.

how can this be? and how can I slove this problem?

Thank you for your answer.

PS. I use MVSC# as tool, in Windows Forms Application Mode

Posted 18-Jun-12 0:37am

windyl3ig

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3 solutions

Solution 1

Hello can you try with replacing this line on top most of your code.

C#

string[] edit_list = txtReqList.Text.Split('\n');
with 
string[] edit_list = txtReqList.Text.Split(',');

now debug your code and check what will be there in edit_list items.
please provide that result if this is not re-solved yet.

Posted 18-Jun-12 0:44am

Tejas Vaishnav

Updated 18-Jun-12 0:45am

v2

Solution 2

1.) Split should be on comma and not on line-break?
2.) Should the connection be closed after the foreach loop?

C#

string[] edit_list = txtReqList.Text.Split('\,');
string query ;
MySqlCommand cmd = new MySqlCommand();
for (int i = 0; i < edit_list.Length; i++)
{
    try
    {
        query = String.Format("UPDATE submit SET submit_status='S' WHERE submit_id = '{0}'", edit_list[i]);

        //Open connection
        if (this.OpenConnection() == true)
        {
            //Assign the query using CommandText
            cmd.CommandText = query;
            //Assign the connection using Connection
            cmd.Connection = connection;
            //Execute query
            cmd.ExecuteNonQuery();
        }
    }
    catch (MySqlException ex)
    {
        MessageBox.Show(ex.ToString());
    }
}

this.CloseConnection();

Posted 18-Jun-12 0:46am

Manas Bhardwaj

Updated 18-Jun-12 0:47am

v2

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OriginalGriff · Accepted Answer · 2012-06-18T00:50:00

Solution 3

Instead of running that in a loop, why not issue just the one command? SQL has an IN clause:

SQL

UPDATE submit SET submit_status ='S' WHERE submit_id IN (list)

All you have to do is build the list:

C#

StringBuilder sb = new StringBuilder();
sb.Append("UPDATE submit SET submit_status ='S' WHERE submit_id IN (");
sb.Append(string.Join(",", edit_list));
sb.Append(")");
cmd.CommandText = sb.ToString();

Posted 18-Jun-12 0:50am

OriginalGriff

Comments

Vani Kulkarni 18-Jun-12 6:51am

Clear and crisp.

windyl3ig 19-Jun-12 2:26am

oh yes, nice and clear, very thank you for your guideline. ^^

OriginalGriff 19-Jun-12 2:36am

You're welcome!