How Can I Reduce Data Of Sql?

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1.00/5 (3 votes)

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hi my friends.
in my table of database , i have field that it name is count.
in my program , i have a button.
when i click button , i want reduce one number from field [count] in database.
for example , value of field [count] is 5.
i want value become 4 when i click button.

how can i do that?

Posted 11-Jun-14 3:54am

Mohammad Hasanpoor

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goathik 11-Jun-14 10:00am

There are some things we need to know.
- ASP.Net or Windows Application?
- Linq or ADO.Net?
- On your table, do you only have always one row with that [Count] column, or more than one row?
- If more than one row, what is the WHERE condition?

Mohammad Hasanpoor 11-Jun-14 10:05am

in windows application and ado.net.
i have two column. [id] and [count]
condition is my textbox=[id]
then reduce that

TheUnknownCoder 11-Jun-14 10:51am

you have to execute a UPDATE command (update tablename set fieldname = value where id = idoftherecordtoupdate)

3 solutions

Solution 1

SQL

Update MyTable 
Set MyCount = (MyCount - 1)
WHERE MyTableID = 23

Posted 11-Jun-14 3:57am

PrakashCs.net

Solution 2

Missng a few details, but presume you mean in sql it could be

SQL

update mytable
set [count] = [count] - 1

but that of cause is a bit odd to use a table for, because a table with just one row?
other wise there must be a key column as well to define the row in your table where there column [count] should be reduced.

if from C# instead, because of the tag on the question you could issue whatever command you want from system.data.sqlclient namespace

C#

public static void DecrementMyTable()
{
    using (var cn = new System.Data.SqlClient.SqlConnection("myconnectionstring"))
    {
       using (var cmd = new System.Data.SqlClient.SqlCommand("my update query"), cn)
         {
              md.ExecuteNonQuery();
         }
     }
}

You could then call a method like the outlined one on your button 'onclick' event, presuming it has runat set to 'server'

Posted 11-Jun-14 4:07am

Thomas Nielsen - getCore

Updated 11-Jun-14 4:09am

v2

Comments

Mohammad Hasanpoor 11-Jun-14 10:12am

sorry .
i have two column. [id] and [count]
condition is my textbox=[id]
then reduce that

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goathik · Accepted Answer · 2014-06-11T04:20:00

click twice on your button and it will send you to .cs file with a blank event. Paste this code into that event:

C#

            try
            { 
                SqlConnection con = new SqlConnection("yourconnectionstringhere");
                con.Open(); 

                SqlCommand cmd = new SqlCommand("UPDATE [nameofthetable] SET [Count] = [Count] - 1 WHERE ID = @ID", con);
//EDIT: protects against sql injection
                cmd.Parameters.Add(new SqlParameter("@ID", txtIDFrom.Text));
                cmd.ExecuteNonQuery(); 
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                con.Close();
            }