c# - Save values from select query then use them in update query SQL Server CE -

i have winforms application sql server ce 3.5 database. want update query , need select query.

here's wrote:

string command1 = "select column1, column2, column3 table1"; string command2 = "update table2 set column2 = @var2, column3 = @var3 column1 = @var1";  using (sqlcecommand cmd1=new sqlcecommand(command1, connection)) {      sqlcedatareader reader;      reader = cmd1.executereader();       while (reader.read())      {          int var1 = (int)reader[0];          int var2 = (int)reader[1];          string var3 = (string)reader[2];           sqlcecommand cmd2= new sqlcecommand (command2, connection);          cmd2.executereader();      } } 

i error

a parameter missing. parameter ordinal=3

you have three parameters in second command (command2) - never define parameters, nor set values them use!

try code:

string command1 = "select column1, column2, column3 table1"; string command2 = "update table2 set column2 = @var2, column3 = @var3 column1 = @var1";  using (sqlcecommand cmd1 = new sqlcecommand(command1, connection)) {      // define "cmd2" here, once, before loop      sqlcecommand cmd2 = new sqlcecommand (command2, connection);       // define parameters      cmd2.parameters.add("@var1", sqldbtype.int);      cmd2.parameters.add("@var2", sqldbtype.int);      cmd2.parameters.add("@var3", sqldbtype.varchar, 100);       sqlcedatareader reader = cmd1.executereader();       while (reader.read())      {          int var1 = (int)reader[0];          int var2 = (int)reader[1];          string var3 = (string)reader[2];           // set *values* of parameters          cmd2.parameters["@var1"].value = var1;          cmd2.parameters["@var2"].value = var2;          cmd2.parameters["@var3"].value = var3;           cmd2.executenonquery();      } }