How To Check A SQL Database Table To See If A Record Exists?
May 10, 2010
I have a SQL database that creates a record for every document uploaded by the user to the server. I want to check this table before a user uploads a document to ensure they don't upload a file with name that already exists.
I know how to make the connection and make the SqlCommand to query the table for an existing record. But I don't know how to check the record count from the sqlCommand I made.
Does that make sense?
Using myConnectionCheck As New SqlConnection(myConnectionStringCheck)
Dim myCommandCheck As New SqlCommand()
myCommandCheck.Connection = myConnectionCheck
myCommandCheck.CommandText = "SELECT * FROM Req_Docs WHERE Doc_Name =" & DocName
myConnectionCheck.Open()
myCommandCheck.ExecuteNonQuery()
End Using
When inserting, i would like to check if the record exists in the table, then if it doesn't, insert it, else either redirecting to a different page, or showing a message box saying "Record already exists" ...
On button click, I want to call a javascript code to check that If the entered BarCode Number in Textbox already exist in Database, then show an alert "Number already exist" else allow user to save and navigate to Default2.aspx
I can able to do the same checking on TextBox OnTextChanged event using c# code, as below:
protected void TextChanged(object sender, EventArgs e) { TextBox txtbarcode = fvIPRForm.FindControl("txtbarcodenumber") as TextBox; if (txtbarcode.Text.Length > 0 && txtbarcode.Text.Length < 11) { string error = "The Barcode Number " + txtbarcode.Text + " is invalid, the barcode length must be 11 character."; ScriptManager.RegisterStartupScript(this, typeof(string), "Successful", "alert('" + error + "');", true);
[Code] ....
Here, IPRRequest is the class/.dll file name and IsValidBarcodeTest is a function defined in the class file
But same checking I tried using the c# code on button's OnClick="btnSave_Click" event, but dont know why this event is not firing, I guess due to CommandArgument on button, but I am not sure.
I tried to illustrate the problem by providing the following instructions, unfortunately the data was deleted and the example failed. It is now working. I have been working through one of Scott Mitchells ASP.NET Application Tutorials Title "Using TemplateFields in the GridView Control"
The URL is ...
The example demonstrates a temporary field being used in different ways, one of which involves dates in a Calender. If the HireDate in the example is deleted or not available the program fails. Providing the date is a valid date it works fine....
I am very new to this and have watched a lot of the videos. While trying out VWD2010 and SQL2008 Express, I come across many things, I just don't know how to do. Here is the latest:
I have a Table UserId - Int - AutoIncrement FirstName - Var(10) LastName - Var(10)
I also have an ASP web page that allow the user to enter a first name and last name. It also has a button to submit. What I would like to do is have a Select statement check to see if the name already exists, then send a comment back to the user via a label. If it doesn't exist, then I would like to Insert the info and then again inform the user via label.
On the code behind, I get lost. (Obviously this doesn't work, but I don't know how to go about getting a results back. Protected Sub bSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles bSubmit.Click
SqlDataSource1.Select(DataSourceSelectArguments.Empty) (get a return) (check return value, if <>0 then lblResults.Text = "exists!" else SqlDataSource1.Insert() lblResults.Text="added!" end if) End Sub
I want to check if the record is already exists before insert using Ajax ActionLink in Create View. I am getting error 'Object reference not set to an instance of an object.' Here is a code in View :
<div class="editor-label"> <%= Html.LabelFor(model => model.PolicyId) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.PolicyId) %> <%= Html.ValidationMessageFor(model => model.PolicyId) %> <em>can not be changed later.</em> //error occurs here <%= Ajax.ActionLink("Check", "CheckIfExists", "Life", new { PolicyId = Model.PolicyId }, null)%> </div>
And Controller action :
public JavaScriptResult CheckIfExists(string PolicyId) { if (lifeRepository.IsExists(PolicyId)) return JavaScript("alert(' Already Exists');"); else return JavaScript("alert(' Not Exists');"); }
Just have a problem, I want people to join a mailing list, I just have a textbox and button. When a user enter's their email address, the address and time are inserted into a database. However, if the same email is added again I would like for a message to appear saying the record already exists.
Can someone show me how to do this, here is my current code:
I would like to check if a particular value already exist in the database Gidview row. If the value already exist, tell the user that he has already entered the record and don't save. otherwise save the record. In my case I want to check the "Random number".
I want to validate the email id in clients side, so that to prevent the postback of page to server, and every user should registered with email id... so i want to validate email id at client side.. i.e. should be check it is exist in the database or not.
I want to check the entered email id already exists in my database or not. For that I need the Text box lost focus event so that I can call it in update panel trigger asynchronously. whereas in my event I can check whether the entered value exists in database or not.
I am counting from a table for that i have written code as below
protected void get_Id_Afterpoint() { int counter = 0; string strSql = "select count(*) as ID from tblEnergy where ID=?"; OdbcCommand com = new OdbcCommand(strSql, con); com.Parameters.AddWithValue("ID", DropDownList1.SelectedValue); OdbcDataAdapter oda = new OdbcDataAdapter(com); DataTable dt = new DataTable(); oda.Fill(dt); if (dt.Rows.Count == 0) { lblID2.Text = "1"; } else { counter = dt.Rows.Count; counter = counter + 1; lblID2.Text = Convert.ToString(counter); } }
there is no record related to DropDownList1.SelectedValue. but as i am counting if(dt.rows.count) and i put break point on the bolded part it shows 1 record. how it can be possible?
Trying to check if an insert of a new record into an SQL table is happening successfully. I can see that the insert is occuring OK but am not getting the verification to happen.
I'm a little new to C#, I'm thinking it may be in the syntax I'm using in my method in the .cs file line 45. Can't seem to fix it right though.
I need to somehow test if a table exists in a database. If it does not then I need to create the table. How can I test for existence of a table using SQL? It seems like some type of SQL logic is needed?
Before a subscription to a newsletter and the record will be inserted, i'd like to check if the record already exist ina sql-server database. This what i've got as dusfar
adres = TxtEmail.Text DBConn.Open() If adres <> "" Then Try DBCmd = New SqlCommand("SELECT COUNT(*) FROM TBL_Subscribers WHERE email = @adres)", DBConn) ''Add DBCmd.Parameters.Add("@Email", SqlDbType.NVarChar).Value = adres DBCmd.ExecuteScalar() DBAdap = New SqlDataAdapter("SELECT * FROM TBL_Subscribers ORDER BY ActivateDate", DBConn) DBAdap.Fill(DS) Catch exp As Exception Response.Write(exp) End Try End if
