Update excel column from MS SQLSERVER table.

From a SQL 2008R2 database, using Exlcel 2010,
I need to update the D cell (Account No)-number by using the values in the C cell (Client ID) -text.
The key to select off the SQL table, CLients, is CLIENT_ID (text) and I need to return the SQL column ACCOUNT_NO (int) and update the column 'Account No' on the excel spreadsheet.
I'm assuming I need to create an ODBC to the SQL Database, which I have.