Check if text exist in my database C#

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hey guys can anyone help me to check if a text exist in database
thats what im writting at this moment
<

connstring = "SERVER=188.121.43.9;PORT=3306;DATABASE=mydbname;UID=mydbusername;PASSWORD=s1996;";
        MySqlConnection conn = new MySqlConnection(connstring);
        MySqlCommand command = conn.CreateCommand();
        command.CommandText = "Select all from dbtable";

>

this is how my DB looks like

<

uname     upass
test      1900
test2     1999

>
i have textbox1
what i want is
for example :
chek if textbox1.text exist at column uname show MessageBox.Show("exist")

What I have tried:

hey guys can anyone help me to check if a text exist in database
thats what im writting at this moment
<
connstring = "SERVER=188.121.43.9;PORT=3306;DATABASE=mydbname;UID=mydbusername;PASSWORD=s1996;";
        MySqlConnection conn = new MySqlConnection(connstring);
        MySqlCommand command = conn.CreateCommand();
        command.CommandText = "Select all from dbtable";
>

this is how my DB looks like

<
uname     upass
test      1900
test2     1999
>
i have textbox1
what i want is
for example : 
chek if textbox1.text exist at column uname show MessageBox.Show("exist")

Posted 7-May-17 13:23pm

Ilyas Zahir

Updated 8-May-17 20:52pm

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Comments

ChauhanAjay 7-May-17 19:47pm

change your query to "Select count(*) from dbtable WHERE uname like '%"+textbox1.text.toString()+"%'". If the result of the query is greater than zero show your message box.

CHill60 8-May-17 7:19am

Do not do this!
That query is vulnerable to SQL Injection attack. Never concatenate user input into your SQL commands.

[no name] 8-May-17 10:00am

Your code would not compile.
If you managed to get it to compile, what possible benefit do you think you get if you call ToString on a string?

2 solutions

Solution 2

I would use ExecuteScalar to be more efficient... like this:

C#

private void btnNext_Click(object sender, EventArgs e)
{
    if (comboBox1.SelectedIndex == -1) return;
    using (var conn = new SqlConnection(connstring))
    {
        conn.Open();
        var cmd = new SqlCommand
        {
            CommandText = "select count(*) from dbtable where UPPER([name])=@name",
            Connection = conn
        };
        cmd.Parameters.AddWithValue("@name", comboBox1.SelectedItem.ToString());
        var res = (int)cmd.ExecuteScalar();
        if (res > 0) 
            MessageBox.Show("exist");
    }
}

Things to note:
- I've used using see Establishing the Connection[^]

Quote:
The Using block in Visual Basic or C# automatically disposes of the connection when the code exits the block, even in the case of an unhandled exception.

- I've used the ExecuteScalar method as it requires less code and fewer resources - see SqlCommand.ExecuteScalar Method (System.Data.SqlClient)[^]
- I check to ensure there is something actually selected on the comboBox before attempting to use the value.

Posted 8-May-17 1:48am

CHill60

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shreyal acharya · Accepted Answer · 2017-05-08T00:24:00

C#

<pre>String connstring = "SERVER=188.121.43.9;PORT=3306;DATABASE=mydbname;UID=mydbusername;PASSWORD=s1996;";
            SqlConnection conn = new SqlConnection(connstring);
            SqlCommand command = conn.CreateCommand();
            command.CommandText = "Select * from dbtable where name=@name";
            command.Parameters.AddWithValue("@name", comboBox1.SelectedValue);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                MessageBox.Show("exist");
            }