To modify existing records, use UPDATE statements.

Update Syntax

The UPDATE statement takes as input a comma-separated list of columns and new column values as name-value pairs in the SET clause, as shown in the following example:

UPDATE <table_name> SET { <column_reference> = <expression> } [ , ... ] WHERE { ListId = <expression>  } [ { AND | OR } ... ] 

<expression> ::=
  | @ <parameter> 
  | ?
  | <literal>

You can use the ExecuteNonQuery method to execute data manipulation commands and retrieve the rows affected, as shown in the following example:

C#

String connectionString = "user=myuseraccount;password=mypassword;URL=http://localhost:2080;qbxmlversion=3.0;";
using (QuickBooksPOSConnection connection = new QuickBooksPOSConnection(connectionString)) {
  int rowsAffected;
  QuickBooksPOSCommand cmd = new QuickBooksPOSCommand("UPDATE Customers SET LastName='Hook' WHERE ListId = @myListId", connection);
  cmd.Parameters.Add(new QuickBooksPOSParameter("myListId","-1045625500155013667"));
  rowsAffected = cmd.ExecuteNonQuery();
}

VB.NET

Dim connectionString As [String] = "user=myuseraccount;password=mypassword;URL=http://localhost:2080;qbxmlversion=3.0;"
Using connection As New QuickBooksPOSConnection(connectionString)
  Dim rowsAffected As Integer
  Dim cmd As New QuickBooksPOSCommand("UPDATE Customers SET LastName='Hook' WHERE ListId = @myListId", connection)
  cmd.Parameters.Add(New QuickBooksPOSParameter("myListId", "-1045625500155013667"))
  rowsAffected = cmd.ExecuteNonQuery()
End Using