If Data already Exists in a Table(Ado.net)

Question

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Here is the code for inserting rows in a table using Ado.net stored procedure.

C#

<pre lang="c#">

 IDbConnection conn = null;
            try
            {
                conn = this.GetConnection();
                conn.Open();


                IDbCommand cmd = conn.CreateCommand();
                //string insertSQL = @"insert into Routes(FromCityId,ToCityId,DistanceInKms,Status) values(@fromcityID,@toCityID,@dis,@st);";
                //cmd.CommandText = insertSQL;
                //cmd.CommandType = CommandType.Text;
                cmd.CommandText = "StoredProcedureName";
                cmd.CommandType = CommandType.StoredProcedure;
                IDataParameter p1 = cmd.CreateParameter();
                p1.ParameterName = "@FromCity";
                p1.Value = RouteInfo.FromCity.CityId;
                cmd.Parameters.Add(p1);
                //........................
                return cmd.ExecuteNonQuery();
            }

              
                

            }
            catch (Common.ConnectToDatabaseException)
            {
                throw new RouteDAOException("Unable to add route");
            }
            catch (Exception)
            {
                throw new RouteDAOException("Unable to add route");
            }
            finally
            {
                conn.Close();
            }

I need a hint to write a code for checking if the row is already exists , if yes , I will have to create an exception.

best regards,

Posted 3-Mar-14 9:13am

JBobby

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Comments

Maciej Los 3-Mar-14 15:20pm

Based on what condition?

Sergey Alexandrovich Kryukov 3-Mar-14 15:22pm

What is going to happen is you add the duplicate record? How about just having a unique key?
—SA

2 solutions

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_Asif_ · Accepted Answer · 2014-03-03T09:50:00

Solution 1

use following IF syntax in the stored procedure

SQL

IF NOT EXISTS(SELECT * FROM TABLE NAME WHERE <duplicate condition="">)
BEING
  --INSERT INTO TABLENAME (columnName1,..) VALUES (...)
END
</duplicate>

Posted 3-Mar-14 9:50am

_Asif_

ZurdoDev · Accepted Answer · 2014-03-03T09:51:00

You will want to check for it in Sql.

In SQL you do

SQL

IF EXISTS(SELECT * FROM table WHERE field = value)
  BEGIN
    -- do an update since it exists
    UPDATE table 
    SET field1 = value. field2 = value2
    WHERE field = value
  END
ELSE
  BEGIN
    -- Since it does not exist, do an insert
    INSERT INTO ...
  END