Data addition and updation in SQL tables

I am sorry mate, it seems you are not only new to SqlClient but also totally new to SQL. I would recommend reading on how UPDATE and INSERT work, have a look around for sample code as to how to do UPDATE and INSERT using SqlCommand. This is not a tutorial section rather a "Quick Answer" section. I have already explained a lot. But i will give you some algorithm in plain English as to what you should be doing:

--get the record count from the table

--if (count == 0)
----execute the INSERT command
--else
----execute the UPDATE command

Also, a couple of points

1) parameterise the INSERT query too like you did for the UPDATE query.

2) instead of doing a SELECT * FROM <tablename>, do a SELECT COUNT(*) FROM <tablename>, this will just give you the record count directly rather than loading the whole table. Unless, you need the table data as well.

That's more than anyone will help you here trying to get one point across. Your code is not wrong, it just needs some rearranging as I mentioned above.

Cheers...

You are running an insert query. An insert query will add new records to the table.
Run an update query in your loop instead. This will update records that already exist.

I reformed the code like this..but it gives me exceptions..can't seem to figure out what i've done wrong in this

for (int ok = 0; ok < CleanedURLlist.Length; ok++)
           {
               leak = ok;



              // cmd = new SqlCommand("UPDATE URL_Entries SET('" + CleanedURLlist[ok] + "' , '" + DateTime.Now + "' , '" + leak + "' )", conneciones);



               cmd = new SqlCommand("UPDATE URL_Entries SET URL=@NewURL, Date=@NewDate" + "WHERE Crawl_ID=@NewCrawl_ID", conneciones);

               cmd.Parameters.AddWithValue("@Crawl_ID", ok);
               cmd.Parameters.AddWithValue("@URL", CleanedURLlist[ok]);
               cmd.Parameters.AddWithValue("@Date", DateTime.Now);


              cmd.ExecuteNonQuery();

               //cmd.ExecuteNonQuery();
           }

ah! i see, there needs to be a space between "@NewDate" and "Where"...and also what Andre mentioned above...

Here you go:

for (int ok = 0; ok < CleanedURLlist.Length; ok++)
           {
               leak = ok;



              // cmd = new SqlCommand("UPDATE URL_Entries SET('" + CleanedURLlist[ok] + "' , '" + DateTime.Now + "' , '" + leak + "' )", conneciones);



               cmd = new SqlCommand("UPDATE URL_Entries SET URL=@NewURL, Date=@NewDate " + "WHERE Crawl_ID=@NewCrawl_ID", conneciones);

               cmd.Parameters.AddWithValue("@NewCrawl_ID", ok);
               cmd.Parameters.AddWithValue("@NewURL", CleanedURLlist[ok]);
               cmd.Parameters.AddWithValue("@NewDate", DateTime.Now);


              cmd.ExecuteNonQuery();

               //cmd.ExecuteNonQuery();           
}

UPDATE query replaces all the initially inserted values with the same entry..specifically the last entry of the table..how do i get it to replace with new values for every entry??

for (int ok1 = 0; ok1 < CleanedURLlist.Length; ok1++)
           {




               // cmd = new SqlCommand("UPDATE URL_Entries SET('" + CleanedURLlist[ok] + "' , '" + DateTime.Now + "' , '" + leak + "' )", conneciones);

               cmd = new SqlCommand("UPDATE URL_Entries SET URL=@NewURL, Date=@NewDate WHERE Crawl_ID=@NewCrawl_ID", conneciones);


               cmd.Parameters.AddWithValue("@NewURL", CleanedURLlist[ok1]);
               cmd.Parameters.AddWithValue("@NewDate", DateTime.Now);
               cmd.Parameters.AddWithValue("@NewCrawl_ID", ok1);


               cmd.ExecuteNonQuery();

               //cmd.ExecuteNonQuery();
           }


           cmd.CommandText = "SELECT * FROM URL_Entries";

           SqlDataReader ReadTable = cmd.ExecuteReader();

           table.Load(ReadTable);

           int jacky = table.Rows.Count;




           //INSERT or UPDATE VALUES IN DATABASE

           if (jacky == 0)
           {
               for (int ok = 0; ok < CleanedURLlist.Length; ok++)
               {


                   cmd = new SqlCommand("insert into URL_Entries values('" + CleanedURLlist[ok] + "' , '" + DateTime.Now + "' , '" + ok + "' )", conneciones);

                   cmd.ExecuteNonQuery();
               }
           }//end of IF