code: func (t *TableMap) SetKeys(isAutoIncr bool, fieldNames ...string) *TableMap {
  	if isAutoIncr && len(fieldNames) != 1 {
  		panic(fmt.Sprintf(
  			"gorp: SetKeys: fieldNames length must be 1 if key is auto-increment. (Saw %v fieldNames)",
  			len(fieldNames)))
  	}
  	t.keys = make([]*ColumnMap, 0)
  	for _, name := range fieldNames {
  		colmap := t.ColMap(name)
  		colmap.isPK = true
  		colmap.isAutoIncr = isAutoIncr
  		t.keys = append(t.keys, colmap)
  	}
  	t.ResetSql()
  
  	return t
  }
docs: // SetKeys lets you specify the fields on a struct that map to primary
  // key columns on the table.  If isAutoIncr is set, result.LastInsertId()
  // will be used after INSERT to bind the generated id to the Go struct.
  //
  // Automatically calls ResetSql() to ensure SQL statements are regenerated.
  //
  // Panics if isAutoIncr is true, and fieldNames length != 1
  //