CODEWITHSUNDEEP
vb.netsql-server-2008
Hoh
Hoh

Reputation: 1184

Find entry from Datatable

I have a WinForm with TextBox inside.
When I activate TextBox.Leave event what I need is to check that entry TextBox.text in my DataSet (Column, not Row) is that entry existing, if not I just have to get a MsgBox("The text you entered already exists, use another one") and it should not be allowed to submit that into DataBase.

Upvotes: 1

Views: 1230

Answers (5)

Jade
Jade

Reputation: 2992

Since you mention DataSet Try this (Dataset is not a table but a collection of table/s)

Dim Tot() as DataRow = yourDataset.Tables("tableName").Select("theColName= '" + TextBox.Text.Trim() + "'")

or

Dim Tot() as DataRow = yourDataset.Tables(IndexNumberOfTable).Select("theColName= '" + TextBox.Text.Trim() + "'")

Upvotes: 0

Magesh
Magesh

Reputation: 393

try this code, I reproduce it for you it is working fine... Double Check your values what you enter in textbox...

Public Class Form1
Dim table As DataTable
Dim ds As DataSet
Private Sub TextBox1_Leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.Leave

    Dim result() As DataRow = ds.Tables(0).Select("Name = '" + TextBox1.Text.Trim() + "'")
    If (result.Length > 0) Then
        MsgBox("Value Exist")
    Else
        'do your calculation
    End If
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    table = New DataTable("Players")

    ' Add two columns.
    table.Columns.Add(New DataColumn("Name", GetType(String)))
    table.Columns.Add(New DataColumn("age", GetType(String)))
    ds.Tables(0).Select()

    table.Rows.Add("Magesh", "25")
    table.Rows.Add("flook", "22")
    ds.Tables.Add(table);


End Sub
End Class

Upvotes: 1

gulshanm01
gulshanm01

Reputation: 195

you can write the sql query as select cols from tablename where col='yourtextboxvalue' execute a datareader using commandObject.executeReader and execute dataReader.Read() method in try block. if value doesn't exist it will go to catch block and show the messagebox there. similar thing to check for username

SqlCommand command = new SqlCommand("Select Password from tblUser where UserName=@username", connection);
            command.Parameters.AddWithValue("@username", txtUsername.Text);     //add parameter to the query

 if (dataReader.Read())      //if any record is available
            {
                dbPassword = dataReader["Password"].ToString();     //get the password for entered username
                if (dbPassword != "" && dbPassword.Equals(password))        
                {

                }

                else
                    MessageBox.Show("Invalid Password","Invalid input");
                connection.Close();     //close the connection
            }

            else 
                MessageBox.Show("Username not found", "Invalid input");     //message will be shown if no record found for the entered user ie.username doesn't exist

Upvotes: 0

Magesh
Magesh

Reputation: 393

Put this code inside textbox1 leave event

Dim result() As DataRow = DataTable.Select("ColumnName = '" + TextBox1.Text.Trim() + "'")

and if result.length > 0 then don't save it....

Upvotes: 0

TamasM
TamasM

Reputation: 11

From database perspective, the easiest way to prevent duplicate entries into a column is if you set a unique constraint on the given column:

CREATE TABLE table1
(
Id int NOT NULL,
Name varchar(255) NOT NULL,
CONSTRAINT uc_Name UNIQUE (Name)
)

Upvotes: 0

Related Questions