.NET (Core and Framework)

public static bool SetCurrentUser(String UserKey, String Password)
 {
     System.Data.SqlServerCe.SqlCeConnection con =
         new System.Data.SqlServerCe.SqlCeConnection();
     con.ConnectionString = DBConnectionstring;
     con.Open();

     DataSet ds1 = new DataSet();

     System.Data.SqlServerCe.SqlCeDataAdapter da =
         new System.Data.SqlServerCe.SqlCeDataAdapter();

     String sQueery = "SELECT * FROM Users WHERE UserKey=" + UserKey +
         "AND Password=" + Password;
     da = new System.Data.SqlClient.SqlDataAdapter(sQueery, con);

     ///////////////////////////////////
     //
     //More to be Written here!
     //
     ///////////////////////////////////



     con.Close();
     return false;

 }

public SqlDataAdapter(
	string selectCommandText,
	SqlConnection selectConnection
)

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