Prevent multiple duplicate data entry into entities database

Question

I am trying to prevent a duplicate data entry into the entity database when inserting into the database. Currently heres my code for inserting into database. I have check many post online but not really sure which one to use as it seems really different. I am trying to prevent duplicate entry for PatientIc and display an error message for it. Thanks in advance!

protected void myGridview_RowCommand(object sender, GridViewCommandEventArgs e)

{

//Insert new Prescription

if (e.CommandName == "Insert")

{

Page.Validate("Add");

if (Page.IsValid)

{

var fRow = myGridview.FooterRow;

TextBox txtPatientName = (TextBox)fRow.FindControl("txtPatientName");

TextBox txtPatientIC = (TextBox)fRow.FindControl("txtPatientIc");

TextBox txtQuantity = (TextBox)fRow.FindControl("txtQuantity");

DropDownList ddType = (DropDownList)fRow.FindControl("ddType");

DropDownList ddState = (DropDownList)fRow.FindControl("ddState");

using (CareGiverEntities dc = new CareGiverEntities())

{

dc.Contacts.Add(new Contact

{

PatientName = txtPatientName.Text.Trim(),

PatientIc= txtPatientIC.Text.Trim(),

Quantity = txtQuantity.Text.Trim(),

MedicineTypeID = Convert.ToInt32(ddType.SelectedValue),

MedicineID = Convert.ToInt32(ddState.SelectedValue),

DatePrecribed= DateTime.Now

});

dc.SaveChanges();

PopulateContacts();

}

}

}

}

Codes for Grid view

<asp:GridView ID="myGridview" runat="server" AutoGenerateColumns="false"

DataKeyNames="ContactID,MedicineTypeID,MedicineID" CellPadding="10" CellSpacing="0"

ShowFooter="true"

CssClass="myGrid" HeaderStyle-CssClass="header" RowStyle-CssClass="trow1"

AlternatingRowStyle-CssClass="trow2" OnRowCommand="myGridview_RowCommand" OnRowCancelingEdit="myGridview_RowCancelingEdit" OnRowDeleting="myGridview_RowDeleting" OnRowEditing="myGridview_RowEditing" OnRowUpdating="myGridview_RowUpdating" AllowPaging="True" AllowSorting="True" >

<EmptyDataTemplate>No results found.</EmptyDataTemplate>

<Columns>

<asp:TemplateField SortExpression="FullName">

<HeaderTemplate>Patient Name</HeaderTemplate>

<ItemTemplate><%#Eval("PatientName") %></ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtPatientName" runat="server" Text='<%#Bind("PatientName") %>' />

<asp:RequiredFieldValidator ID="rfCPEdit" runat="server" ForeColor="Red" ErrorMessage="*"

Display="Dynamic" ValidationGroup="edit" ControlToValidate="txtPatientName">Required</asp:RequiredFieldValidator>

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtPatientName" runat="server"></asp:TextBox><br />

<asp:RequiredFieldValidator ID="rfCP" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="Add" ControlToValidate="txtPatientName">Required</asp:RequiredFieldValidator>

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField>

<HeaderTemplate>Patient IC</HeaderTemplate>

<ItemTemplate><%#Eval("PatientIc") %></ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtPatientIc" runat="server" Text='<%#Bind("PatientIc") %>' />

<asp:RequiredFieldValidator ID="rfCOEdit" runat="server" ForeColor="Red" ErrorMessage="*"

Display="Dynamic" ValidationGroup="edit" ControlToValidate="txtPatientIc">Required</asp:RequiredFieldValidator>

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtPatientIc" runat="server"></asp:TextBox><br />

<asp:RequiredFieldValidator ID="rfCO" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="Add" ControlToValidate="txtPatientIC">Required</asp:RequiredFieldValidator>

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField>

<HeaderTemplate>Quantity</HeaderTemplate>

<ItemTemplate><%#Eval("Quantity") %></ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtQuantity" runat="server" Text='<%#Bind("Quantity") %>' />

<asp:RequiredFieldValidator ID="rfCNEdit" runat="server" ErrorMessage="*"

Display="Dynamic" ForeColor="Red" ValidationGroup="edit" ControlToValidate="txtQuantity">Required</asp:RequiredFieldValidator>

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtQuantity" runat="server"></asp:TextBox><br />

<asp:RequiredFieldValidator ID="rfCN" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="Add" ControlToValidate="txtQuantity">Required</asp:RequiredFieldValidator>

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField>

<HeaderTemplate>Medicine Type</HeaderTemplate>

<ItemTemplate><%#Eval("MedicineType") %></ItemTemplate>

<EditItemTemplate>

<asp:DropDownList ID="ddType" runat="server" AutoPostBack="true"

OnSelectedIndexChanged="ddCountry_SelectedIndexChanged">

<asp:ListItem Text="Select Medicine type" Value="0"></asp:ListItem>

</asp:DropDownList>

<asp:RequiredFieldValidator ID="rfCEdit" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="edit" ControlToValidate="ddType" InitialValue="0">

Required

</asp:RequiredFieldValidator>

</EditItemTemplate>

<FooterTemplate>

<asp:DropDownList ID="ddType" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddCountry_SelectedIndexChanged">

<asp:ListItem Text="Select Medicine Type" Value="0"></asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator ID="rfC" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="Add" ControlToValidate="ddType" InitialValue="0">Required</asp:RequiredFieldValidator>

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField>

<HeaderTemplate>Medicine Name</HeaderTemplate>

<ItemTemplate><%#Eval("MedicineName") %></ItemTemplate>

<EditItemTemplate>

<asp:DropDownList ID="ddState" runat="server">

<asp:ListItem Text="Select Medicine" Value="0"></asp:ListItem>

</asp:DropDownList>

<asp:RequiredFieldValidator ID="rfSEdit" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="edit" ControlToValidate="ddState" InitialValue="0">

Required

</asp:RequiredFieldValidator>

</EditItemTemplate>

<FooterTemplate>

<asp:DropDownList ID="ddState" runat="server">

<asp:ListItem Text="Select Medicine" Value="0"></asp:ListItem>

</asp:DropDownList><br />

<asp:RequiredFieldValidator ID="rfS" runat="server" ErrorMessage="*"

ForeColor="Red" Display="Dynamic" ValidationGroup="Add" ControlToValidate="ddState"

InitialValue="0">Required</asp:RequiredFieldValidator>

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField>

<ItemTemplate>

<asp:LinkButton ID="lbEdit" runat="server" CommandName="Edit">Edit</asp:LinkButton>

&nbsp;|&nbsp;

<asp:LinkButton ID="lbDelete" runat="server" CommandName="Delete" OnClientClick="return confirm('Are you confirm?')">Delete</asp:LinkButton>

</ItemTemplate>

<EditItemTemplate>

<asp:LinkButton ID="lbUpdate" runat="server" CommandName="Update" ValidationGroup="edit">Update</asp:LinkButton>

&nbsp;|&nbsp;

<asp:LinkButton ID="lbCancel" runat="server" CommandName="Cancel">Cancel</asp:LinkButton>

</EditItemTemplate>

<FooterTemplate>

<asp:Button ID="btnInsert" runat="server" Text="Prescribe" CommandName="Insert" ValidationGroup="Add" />

</FooterTemplate>

</asp:TemplateField>

</Columns>

</asp:GridView>