Hi nedash,

Refer below sample.

HTML

<asp:Button runat="server" Text="Download" OnClick="OnDownload" />

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.IO;
using System.Text;

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.IO
Imports System.Text

Code

C#

string primaryKey, tableName = "Customers";
string updateAdd = "";
protected void OnDownload(object sender, EventArgs e)
{
    DownloadScript();
}

public void DownloadScript()
{
    string iDValues = "", insertQry, updateQry;
    int i = 0;
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    SqlConnection con = new SqlConnection(conString);
    SqlCommand cmd = new SqlCommand("select * from Customers", con);
    primaryKey = GetPrimaryKey(tableName, conString);
    insertQry = "";
    con.Open();

    if (File.Exists(Server.MapPath("~/" + tableName + ".sql")))
    {
        File.Delete(Server.MapPath("~/" + tableName + ".sql"));
    }
    SqlDataReader sdr = cmd.ExecuteReader();
    while (sdr.Read())
    {
        i = i + 1;
        updateAdd = "";
        insertQry = "";

        string celldata = "", coulmenName = "";
        for (int j = 0; j < sdr.FieldCount; j++)
        {
            if (j > 0)
            {
                coulmenName += "," + sdr.GetName(j).ToString();
                celldata += ",'" + sdr[j].ToString() + "'";
            }
            else
            {
                coulmenName += sdr.GetName(j).ToString();
                celldata += "'" + sdr[j].ToString() + "'";
            }
            if (primaryKey == sdr.GetName(j).ToString())
            {
                iDValues = sdr[j].ToString();
            }
            if (iDValues != null)
            {
                updateQry = UpdateQuery(coulmenName, celldata, primaryKey, iDValues);
                updateAdd += updateQry;
                insertQry = InsertQuery(coulmenName, celldata, tableName);
            }
        }
        WriteScripts(tableName, insertQry, updateAdd, iDValues, primaryKey, i);
    }

    // Download the sql script file.
    if (File.Exists(Server.MapPath("~/" + tableName + ".sql")))
    {
        byte[] bytes = File.ReadAllBytes(Server.MapPath("~/" + tableName + ".sql"));
        File.Delete(Server.MapPath("~/" + tableName + ".sql"));

        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "";
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        Response.ContentType = ContentType;
        Response.AppendHeader("Content-Disposition", "attachment; filename=" + tableName + ".sql");
        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.End();
    }
}

public string GetPrimaryKey(string tableName, string cnnString)
{
    string iD = "";
    SqlConnection con = new SqlConnection(cnnString);
    SqlCommand cmd = new SqlCommand("sp_pkeys", con);
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.Add("@table_name", SqlDbType.NVarChar).Value = tableName;
    con.Open();
    SqlDataReader sdr = cmd.ExecuteReader();
    while (sdr.Read())
    {
        iD = sdr[3].ToString();
    }
    con.Close();

    return iD;
}

public void WriteScripts(string tableName, string insertqry, string updateQuery, string iDValues, string PrimaryKey, int i)
{
    string script = "";
    updateQuery = "UPDATE " + tableName + " SET " + updateQuery + " WHERE " + PrimaryKey + " = ' " + iDValues + "'";
    int index = updateQuery.LastIndexOf(",");
    string updatqry = updateQuery.Remove(index, 1);
    if (i == 1)
    {
        script += "DECLARE @updateCount INT;" + Environment.NewLine;
        script += "DECLARE @insertCount INT;" + Environment.NewLine;
        script += "DECLARE @count INT;" + Environment.NewLine;
        script += " SET @updateCount = 0;" + Environment.NewLine;
        script += " SET @insertCount = 0;" + Environment.NewLine;
        script += "SELECT @count = COUNT(*) FROM [" + tableName + "] WHERE [" + PrimaryKey + "] = '" + iDValues + "'" + Environment.NewLine;
        script += "IF @count = 0" + Environment.NewLine;
        script += "BEGIN " + Environment.NewLine;
        script += "SET IDENTITY_INSERT " + tableName + " ON" + Environment.NewLine;
        script += insertqry + " " + Environment.NewLine;
        script += "SET IDENTITY_INSERT " + tableName + " OFF" + Environment.NewLine;
        script += " SET @insertCount = @insertCount + 1 " + Environment.NewLine;
        script += "END" + Environment.NewLine;
        script += "ELSE" + Environment.NewLine;
        script += "BEGIN" + Environment.NewLine;
        script += updatqry + "" + Environment.NewLine;
        script += " SET @updateCount = @updateCount + 1 " + Environment.NewLine;
        script += "END" + Environment.NewLine;
        StreamWriter sw = new StreamWriter(Server.MapPath("~/" + tableName + ".sql"), true, Encoding.UTF8);
        sw.Write(script);
        sw.Close();
    }
    else
    {
        script += "SELECT @count = COUNT(*) FROM [" + tableName + "] WHERE [" + PrimaryKey + "] = '" + iDValues + "'" + Environment.NewLine;
        script += "IF @count = 0" + Environment.NewLine;
        script += "BEGIN " + Environment.NewLine;
        script += "SET IDENTITY_INSERT " + tableName + " ON" + Environment.NewLine;
        script += insertqry + "" + Environment.NewLine;
        script += "SET IDENTITY_INSERT " + tableName + " OFF" + Environment.NewLine;
        script += "SET @insertCount = @insertCount + 1 " + Environment.NewLine;
        script += "END" + Environment.NewLine;
        script += "ELSE" + Environment.NewLine;
        script += "BEGIN " + Environment.NewLine;
        script += updatqry + "" + Environment.NewLine;
        script += "SET @updateCount = @updateCount + 1 " + Environment.NewLine;
        script += "END" + Environment.NewLine;
        StreamWriter sw = new StreamWriter(Server.MapPath("~/" + tableName + ".sql"), true, Encoding.UTF8);
        sw.Write(script);
        sw.Close();
    }
}

public string InsertQuery(string columnName, string cellData, string tableName)
{
    return "INSERT INTO " + tableName + " (" + columnName + ") VALUES (" + cellData + ")";
}

public string UpdateQuery(string columnName, string cellData, string Names, string value)
{
    string iDName, iDValue, ud = "", name = "", values = "";
    iDName = Names;
    iDValue = value;
    if (iDName != null)
    {
        int indexcolumn = columnName.LastIndexOf(",");
        int indexValues = cellData.LastIndexOf(",");
        if (indexcolumn > 0 && indexValues > 0)
        {
            columnName = columnName.Substring(indexcolumn);
            cellData = cellData.Substring(indexValues);
            name = columnName.Replace(",", "");
            values = cellData.Replace(",", "");
            if (name != iDName && values != iDValue)
            {
                ud = name + "=" + values + ",";
            }
        }
        else
        {
            name = columnName;
            values = cellData;
            if (name != iDName && values != iDValue)
            {
                ud = name + "=" + values + ",";
            }
        }
    }
    return ud;
}

VB.Net

Private primaryKey As String, tableName As String = "Customers"
Private updateAdd As String = ""

Protected Sub OnDownload(ByVal sender As Object, ByVal e As EventArgs)
    DownloadScript()
End Sub

Public Sub DownloadScript()
    Dim insertQry, updateQry As String, iDValues As String = ""
    Dim i As Integer = 0
    Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Dim con As SqlConnection = New SqlConnection(conString)
    Dim cmd As SqlCommand = New SqlCommand("select * from Customers", con)
    primaryKey = GetPrimaryKey(tableName, conString)
    insertQry = ""
    con.Open()

    If File.Exists(Server.MapPath("~/" & tableName & ".sql")) Then
        File.Delete(Server.MapPath("~/" & tableName & ".sql"))
    End If

    Dim sdr As SqlDataReader = cmd.ExecuteReader()

    While sdr.Read()
        i = i + 1
        updateAdd = ""
        insertQry = ""
        Dim celldata As String = "", coulmenName As String = ""

        For j As Integer = 0 To sdr.FieldCount - 1

            If j > 0 Then
                coulmenName += "," & sdr.GetName(j).ToString()
                celldata += ",'" & sdr(j).ToString() & "'"
            Else
                coulmenName += sdr.GetName(j).ToString()
                celldata += "'" & sdr(j).ToString() & "'"
            End If

            If primaryKey = sdr.GetName(j).ToString() Then
                iDValues = sdr(j).ToString()
            End If

            If iDValues IsNot Nothing Then
                updateQry = UpdateQuery(coulmenName, celldata, primaryKey, iDValues)
                updateAdd += updateQry
                insertQry = InsertQuery(coulmenName, celldata, tableName)
            End If
        Next

        WriteScripts(tableName, insertQry, updateAdd, iDValues, primaryKey, i)
    End While

    If File.Exists(Server.MapPath("~/" & tableName & ".sql")) Then
        Dim bytes As Byte() = File.ReadAllBytes(Server.MapPath("~/" & tableName & ".sql"))
        File.Delete(Server.MapPath("~/" & tableName & ".sql"))
        Response.Clear()
        Response.Buffer = True
        Response.Charset = ""
        Response.Cache.SetCacheability(HttpCacheability.NoCache)
        Response.ContentType = ContentType
        Response.AppendHeader("Content-Disposition", "attachment; filename=" & tableName & ".sql")
        Response.BinaryWrite(bytes)
        Response.Flush()
        Response.End()
    End If
End Sub

Public Function GetPrimaryKey(ByVal tableName As String, ByVal cnnString As String) As String
    Dim iD As String = ""
    Dim con As SqlConnection = New SqlConnection(cnnString)
    Dim cmd As SqlCommand = New SqlCommand("sp_pkeys", con)
    cmd.CommandType = CommandType.StoredProcedure
    cmd.Parameters.Add("@table_name", SqlDbType.NVarChar).Value = tableName
    con.Open()
    Dim sdr As SqlDataReader = cmd.ExecuteReader()

    While sdr.Read()
        iD = sdr(3).ToString()
    End While

    con.Close()
    Return iD
End Function

Public Sub WriteScripts(ByVal tableName As String, ByVal insertqry As String, ByVal updateQuery As String, ByVal iDValues As String, ByVal PrimaryKey As String, ByVal i As Integer)
    Dim script As String = ""
    updateQuery = "UPDATE " & tableName & " SET " & updateQuery & " WHERE " & PrimaryKey & " = ' " & iDValues & "'"
    Dim index As Integer = updateQuery.LastIndexOf(",")
    Dim updatqry As String = updateQuery.Remove(index, 1)

    If i = 1 Then
        script += "DECLARE @updateCount INT;" & Environment.NewLine
        script += "DECLARE @insertCount INT;" & Environment.NewLine
        script += "DECLARE @count INT;" & Environment.NewLine
        script += " SET @updateCount = 0;" & Environment.NewLine
        script += " SET @insertCount = 0;" & Environment.NewLine
        script += "SELECT @count = COUNT(*) FROM [" & tableName & "] WHERE [" & PrimaryKey & "] = '" & iDValues & "'" & Environment.NewLine
        script += "IF @count = 0" & Environment.NewLine
        script += "BEGIN " & Environment.NewLine
        script += "SET IDENTITY_INSERT " & tableName & " ON" & Environment.NewLine
        script += insertqry & " " & Environment.NewLine
        script += "SET IDENTITY_INSERT " & tableName & " OFF" & Environment.NewLine
        script += " SET @insertCount = @insertCount + 1 " & Environment.NewLine
        script += "END" & Environment.NewLine
        script += "ELSE" & Environment.NewLine
        script += "BEGIN" & Environment.NewLine
        script += updatqry & "" & Environment.NewLine
        script += " SET @updateCount = @updateCount + 1 " & Environment.NewLine
        script += "END" & Environment.NewLine
        Dim sw As StreamWriter = New StreamWriter(Server.MapPath("~/" & tableName & ".sql"), True, Encoding.UTF8)
        sw.Write(script)
        sw.Close()
    Else
        script += "SELECT @count = COUNT(*) FROM [" & tableName & "] WHERE [" & PrimaryKey & "] = '" & iDValues & "'" & Environment.NewLine
        script += "IF @count = 0" & Environment.NewLine
        script += "BEGIN " & Environment.NewLine
        script += "SET IDENTITY_INSERT " & tableName & " ON" & Environment.NewLine
        script += insertqry & "" & Environment.NewLine
        script += "SET IDENTITY_INSERT " & tableName & " OFF" & Environment.NewLine
        script += "SET @insertCount = @insertCount + 1 " & Environment.NewLine
        script += "END" & Environment.NewLine
        script += "ELSE" & Environment.NewLine
        script += "BEGIN " & Environment.NewLine
        script += updatqry & "" & Environment.NewLine
        script += "SET @updateCount = @updateCount + 1 " & Environment.NewLine
        script += "END" & Environment.NewLine
        Dim sw As StreamWriter = New StreamWriter(Server.MapPath("~/" & tableName & ".sql"), True, Encoding.UTF8)
        sw.Write(script)
        sw.Close()
    End If
End Sub

Public Function InsertQuery(ByVal columnName As String, ByVal cellData As String, ByVal tableName As String) As String
    Return "INSERT INTO " & tableName & " (" & columnName & ") VALUES (" & cellData & ")"
End Function

Public Function UpdateQuery(ByVal columnName As String, ByVal cellData As String, ByVal Names As String, ByVal value As String) As String
    Dim iDName, iDValue As String, ud As String = "", name As String = "", values As String = ""
    iDName = Names
    iDValue = value

    If iDName IsNot Nothing Then
        Dim indexcolumn As Integer = columnName.LastIndexOf(",")
        Dim indexValues As Integer = cellData.LastIndexOf(",")

        If indexcolumn > 0 AndAlso indexValues > 0 Then
            columnName = columnName.Substring(indexcolumn)
            cellData = cellData.Substring(indexValues)
            name = columnName.Replace(",", "")
            values = cellData.Replace(",", "")

            If name <> iDName AndAlso values <> iDValue Then
                ud = name & "=" & values & ","
            End If
        Else
            name = columnName
            values = cellData

            If name <> iDName AndAlso values <> iDValue Then
                ud = name & "=" & values & ","
            End If
        End If
    End If

    Return ud
End Function