Name
pg_select -- loop over the result of a SELECT statement
Synopsis
pg_select dbHandle queryString
  arrayVar queryProcedure
Inputs
- dbHandle
- Specifies a valid database handle. 
- queryString
- Specifies a valid SQL select query. 
- arrayVar
- Array variable for tuples returned. 
- queryProcedure
- Procedure run on each tuple found. 
Outputs
- resultHandle
-    the return result is either an error message or a handle for a query result. 
Description
pg_select submits a SELECT query to the
Postgres backend, and executes a
given chunk of code for each tuple in the result.
  The queryString
  must be a SELECT statement.  Anything else returns an error.
  The arrayVar
  variable is an array name used in the loop.  For each tuple,
  arrayVar is filled in
  with the tuple field values, using the field names as the array
  indexes.  Then the
  queryProcedure
  is executed.
Usage
This would work if table "table" has fields "control" and "name"
(and, perhaps, other fields):
	pg_select $pgconn "SELECT * from table" array {
		puts [format "%5d %s" array(control) array(name)]
	}