Archive for the ‘MS SQL Server’ Category.

What is the difference between a DataSet and a DataTable?

What is the difference between a DataSet and a DataTable?
Here is a link to the MSDN class information for both:
DataSet Class
DataTable Class

So a DataTable is just a table.

However, a DataSet is a collection of tables that can have their data linked together with a DataRelation Class.

So when accessing a database, which should you use?
Well, if you only need a single table, then just use a DataTable.
However, if you need multiple tables and those tables may have some type of relationship, use a DataSet.

How do I get the number of rows returned from a Microsoft SQL Query in C#?

How do I get the number of rows returned from a SQL Query in C#?

Having used other languages where this is much simpler, I was surprised at how “not simple” this was in C#. I expected it to be a little more complex than in some scripting language such as PHP, but it was way more complex.

Here is how I do it:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace CountRows
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create a string to hold the database connection string
            string sdwConnectionString = @"Data Source = ServerName; user id=UserName; password=P@sswd!; Initial Catalog = DatabaseName;";

            // Create a string to hold the database connection string
            string query = "SELECT * FROM MyTable";

            // Pass both strings to a new SqlCommand object.
            SqlCommand queryCommand = new SqlCommand(query, sdwDBConnection);

            // Create a SqlDataReader
            SqlDataReader queryCommandReader = queryCommand.ExecuteReader();

            // Create a DataTable object to hold all the data returned by the query.
            DataTable dataTable = new DataTable();
            dataTable.Load(queryCommandReader);

            // The DataTable object has a nice DataTable.Rows.Count property that returns the row count.
            int rowCount = rowCount = dataTable.Rows.Count;
        }
    }
}

Now doing it this way, you also have the data available in the DataTable dataTable object so you don’t have to go to the database and get it again.

 

Return to ADO.NET and Database with C#

How I get the number of a rows in a Micorosft SQL table using C#?

How I get the number of rows in a table using C#?

Here is a step by step:

Step 1 – Create a new class: (attached click here: SQLTableRowCounter.cs)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace SQLTableRowCounter
{
    class SQLTableRowCounter
    {
        private string mCountQuery;
        private SqlConnection mConnection;
        private int mNumberOfRows;

        public SQLTableRowCounter(String inTableName, SqlConnection inConnection)
        {
            mCountQuery = "SELECT COUNT(*) FROM " + inTableName;
            mConnection = inConnection;
            mConnection.Open();
            SqlCommand mCountQueryCommand = new SqlCommand(mCountQuery, mConnection);
            mNumberOfRows = (int)mCountQueryCommand.ExecuteScalar();
        }

        public int NumberOfRows
        {
            get { return mNumberOfRows; }
            set { mNumberOfRows = value; }
        }
    }
}

Step 2 – Now create the object and get the value:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace SQLTableRowCounter
{
    class Program
    {
        static void Main(string[] args)
        {
             string connectionString = @"Data Source = ServerName; user id=UserName; password=P@sswd!; Initial Catalog = DatabaseName;";
             SqlConnection connection = new SqlConnection(connectionString);
             SQLTableRowCounter qrc = new SQLTableRowCounter("TableName", connection);
             int numRows = qrc.NumberOfRows;
        }
    }
}