SQLのお勉強

DBに市場データを放り込むことにしたので、それを活用するためにpostgres SQLの勉強。
今日はコロン二つによる型変換とテーブルの外部結合がわかった。

 select fnkl201012.date,
  fnkl201012.open/ftpl201012.open::dec as ntopen,
  fnkl201012.close/ftpl201012.close::dec as ntclose
   from fnkl201012,ftpl201012
    where fnkl201012.date=ftpl201012.date
     order by fnkl201012.date;
    date    |       ntopen        |       ntclose
------------+---------------------+---------------------
 2010-09-01 | 11.0579345088161209 | 11.1069418386491557
 2010-09-02 | 11.0988336402701044 | 11.0536044362292052
 2010-09-03 | 11.1042944785276074 | 11.0757946210268949
 2010-09-06 | 11.1232544019429265 | 11.1271850512356841
 2010-09-07 | 11.0949788263762855 | 11.0949788263762855
 2010-09-08 | 11.0268948655256724 | 11.0412815773259396
 2010-09-09 | 11.0677242220866382 | 11.0661764705882353
 2010-09-10 | 11.0248635536688902 | 11.1138014527845036
 2010-09-13 | 11.1644657863145258 | 11.1499096929560506
 2010-09-14 | 11.1365003006614552 | 11.1714975845410628
 2010-09-15 | 11.1529126213592233 | 11.2604042806183115
 2010-09-16 | 11.2536786344908770 | 11.2731619844590556
 2010-09-17 | 11.2950916617386162 | 11.3254437869822485
 2010-09-21 | 11.2961876832844575 | 11.3250148544266191
 2010-09-22 | 11.2893642305407011 | 11.3333333333333333
 2010-09-24 | 11.3369630973986691 | 11.3389626055488540
 2010-09-27 | 11.3772455089820359 | 11.3033175355450237
 2010-09-28 | 11.2662721893491124 | 11.2707838479809976
 2010-09-29 | 11.2899408284023669 | 11.2470588235294118
 2010-09-30 | 11.2669416617560401 | 11.3248638838475499
 2010-10-01 | 11.3701923076923077 | 11.3542926239419589
 2010-10-04 |

NT倍率を表示してみました。