* select from where
  To execute the source blocks load org-babel and hit "C-c C-C" with
  point inside the block.

  The following function implements a simple SELECT-FROM-WHERE clause
  for remote org-tables:
#+srcname: my-select-from-where
#+begin_src emacs-lisp :tangle no :results silent
  (require 'org-babel-ref)
  
  (defun my-select-from-where (select-column table-name where-column where-entry)
    "Get an entry of a remote table with #+TBLNAME: `table-name'
  using a simple where clause:
  
  SELECT select-column FROM table-name WHERE where-column = where-entry
  
  `select-column' and `where-column' are zero-based indices (first
  column has index 0).  The test is done using `equal'.
  
  Example:
  For the following tabe
  
  ,#+TBLNAME: mytable
  | 0815 | foo |
  | 4711 | bar |
  
  the function call
  
    (my-select-from-where 1 \"mytable\" 0 4711)
  
  returns \"bar\"."
    (let ((table (org-babel-ref-resolve-reference table-name nil))
          select-entry)
      (dolist (row table)
        (if (equal (nth where-column row) where-entry)
            (if (null select-entry)
                (setq select-entry (nth select-column row))
              (error "where-entry is not unique"))))
      select-entry))
#+end_src
  This requires the column which is used for indexing to have unique
  entries.

  Let's take this table for testing:
#+TBLNAME: mytable1
| 0815 | foo |
| 4711 | bar |

  First select the second column of the row where the first column
  equals 0815, then select the first column of the row where the
  second column equals "foo":
#+srcname: test-select
#+begin_src emacs-lisp :tangle no
  (list
   (my-select-from-where 1 "mytable1" 0 0815)
   (my-select-from-where 0 "mytable1" 1 "foo"))
#+end_src


  Unfortunately, a table name ("mytable1") is replaced by something
  obscure, when we use it in the #+TBLFM line.  Also, the function
  my-select-from-where converts numeric table entries to a numeric
  type, in contrast to the referencing in the #+TBLFM line.  These
  helper functions work around these problems:
#+srcname: my-select-from-where-helpers
#+begin_src emacs-lisp :tangle no :results silent
  (defun my-select-1-from-table-where-0= (where-entry)
    (my-select-from-where 1 "mytable1" 0
                          (if (numberp where-entry) where-entry
                            (string-to-number where-entry))))
  
  (defun my-select-0-from-table-where-1= (where-entry)
    (my-select-from-where 0 "mytable1" 1 where-entry))
#+end_src

  Testing the helpers:
#+srcname: test-helpers
#+begin_src emacs-lisp :tangle no
  (list
    (my-select-1-from-table-where-0= 4711)
    (my-select-0-from-table-where-1= "bar"))
#+end_src


  Now we can reference remote table rows using a dynamic index (press
  "C-c C-c" in the #+TBLFM line):
#+TBLNAME: mytable2
| 4711 |   |   |
| 0815 |   |   |
#+TBLFM: $2='(my-select-1-from-table-where-0= $1)::$3='(my-select-0-from-table-where-1= $2)