bool value query

Question

I am getting an error when querying a bool value column in a SQL query. Nothing I try is right. I need help on this.

OleDbCommand cmd1 = new OleDbCommand("select tamamlandi,okulno,adisoyadi from ogrencigorusme WHERE Convert.ToBoolean(tamamlandi) = 1 and okulno = '" + txt_Noara.Text + "'", conn);

OleDbDataReader dr1 = cmd1.ExecuteReader();

my other attempts : tamamlandi=true or tamamlandi= 1

Naimish Makwana · Answer

In SQL, boolean values are often represented as 0 and 1 , with 1 representing true and 0 representing false . However, the way you’re trying to convert and compare might be causing the issue. In your SQL query, you’re trying to use Convert.ToBoolean(tamamlandi) = 1 , which is not a valid SQL syntax. Instead, you should directly compare tamamlandi with 1 or true (depending on your database). Here’s how you can modify your command: OleDbCommand cmd1 = new OleDbCommand("SELECT tamamlandi, okulno, adisoyadi FROM ogrencigorusme WHERE tamamlandi = true AND okulno = '" + txt_Noara.Text + "'", conn); Or if tamamlandi is stored as an integer: OleDbCommand cmd1 = new OleDbCommand("SELECT tamamlandi, okulno, adisoyadi FROM ogrencigorusme WHERE tamamlandi = 1 AND okulno = '" + txt_Noara.Text + "'", conn); Please replace true or 1 with the correct representation of boolean in your database. Also, please note that concatenating strings to form SQL queries can lead to SQL injection attacks. Consider using parameterized queries to avoid this. Here’s how you can do it: OleDbCommand cmd1 = new OleDbCommand("SELECT tamamlandi, okulno, adisoyadi FROM ogrencigorusme WHERE tamamlandi = true AND okulno = ?", conn); cmd1.Parameters.Add(new OleDbParameter("okulno", txt_Noara.Text)); Again, replace true with the correct representation of boolean in your database. Thanks

Jignesh Kumar · Answer

Hello Mehmat, Please use this one, OleDbCommand cmd1 = new OleDbCommand("SELECT tamamlandi, okulno, adisoyadi FROM ogrencigorusme WHERE tamamlandi = True AND okulno = @OkulNo", conn); cmd1.Parameters.AddWithValue("@OkulNo", txt_Noara.Text); OleDbDataReader dr1 = cmd1.ExecuteReader(); OR OleDbCommand cmd1 = new OleDbCommand("select tamamlandi,okulno,adisoyadi from ogrencigorusme WHERE IIF(amamlandi,1,0) = 1 and okulno = '" + txt_Noara.Text + "'", conn); OleDbDataReader dr1 = cmd1.ExecuteReader();

Jignesh Kumar · Answer

Hello What is data-type of this column, "tamamlandi", Could you please run this query on database and share result here, select tamamlandi,okulno,adisoyadi from ogrencigorusme

Mehmet Fatih · Answer

I am sorry Jignesh, it was my fault. I have found the error. I had written the textbox name incorrectly..

Mehmet Fatih · Answer

It gives this error. function convert.toInt32 not defined in expression

Jignesh Kumar · Answer

OleDbCommand cmd1 = new OleDbCommand("select tamamlandi,okulno,adisoyadi from ogrencigorusme WHERE Convert.ToInt32(tamamlandi) = 1 and okulno = '" + txt_Noara.Text + "'", conn); OleDbDataReader dr1 = cmd1.ExecuteReader();

Mehmet Fatih · Answer

I am sorry to say that I have tried all of them but the result is the same.

Rohini Parade · Answer

You are using c# function in query which will not support because while executing query SQL server don't know definition of c# convert function. If that is table column you can directly use ColumnName=1. Casting not required