Data type mismatch in criteria expression.

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i am trying to get all values of a particular id from my access database. here is the code:

C#

conn.Open();
           CommandText = "SELECT * FROM arrear where [uid] ='"+ uidd+"'";
           cmd = new OleDbCommand(CommandText);
           cmd.Connection = conn;

           dr = cmd.ExecuteReader();

when i run the prgram it gives the following error
Data type mismatch in criteria expression.
could somebody please tell me what is wrong with my code
thanks in advance

Posted 22-Aug-12 18:03pm

saifullahiit

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Kuthuparakkal 23-Aug-12 0:08am

plz find the answer suggested

4 solutions

Solution 1

uid might be stored as int and you supply a string values.

also try this :

C#

CommandText = "SELECT * FROM arrear where [uid] =" + uidd ;

Posted 22-Aug-12 18:08pm

Kuthuparakkal

Updated 22-Aug-12 18:58pm

v2

Comments

saifullahiit 23-Aug-12 0:15am

Syntax error (comma) in query expression '[uid] =System.Windows.Forms.Label

Solution 2

Fix the syntax error.

CommandText = string.Format("SELECT * FROM arrear where [uid] = {0}",uidd);

Posted 22-Aug-12 18:18pm

pramod.hegde

Solution 4

Your uid from table having int as datatype.
so convert parameter to int & also remove single quote as folllows

C#

CommandText = "SELECT * FROM arrear where [uid] ="+ Convert.ToInt32(uidd) +"";

Posted 22-Aug-12 18:51pm

pradiprenushe

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CodeHawkz · Accepted Answer · 2012-08-22T18:50:00

Seriously? :S Not a single soul provided an answer with a SqlParameter. It's sad to see a professional community still encourages people to generate SQL as string which is vulnerable to so many hacks.

C#

OleDbConnection connection = new OleDbConnection("Read your connection string from a config file. May be an encrypted one");

try
{
	connection.Open();

	// This automatically sets the command.Connection property
	OleDbCommand command = connection.CreateCommand();
	command.CommandType = CommandType.Text;
	command.CommandText = "SELECT * FROM arrear where [uid] = @uid";

	// The point of parameters is that they escape unsafe values, so that
	// your code doesn't break or is not vulnerable for basic hacks
	OleDbParameter parameter = command.CreateParameter();
	parameter.ParameterName = "@uid";
	parameter.DbType = DbType.Int32;
	parameter.Value = someLabel.Text;
	command.Parameters.Add(parameter);

	// Check out the 'CommandBehavior' enum, which can be passed as a parameter to this method
	// Very useful in some occasions
	OleDbDataReader reader = command.ExecuteReader();
}
finally
{
	if (connection.State != ConnectionState.Closed)
		connection.Close();
}

This will take away many data formatting issues, unless the value you pass into the parameter fails to be converted to the specified data type specified in the parameter DbType

Hope this helps, regards