できるPRO MySQL できるPROシリーズ Kindle版の内容をまとめる。
SELECT Name, Population / 1000 FROM country
WHERE Region = 'Eastern Asia';
float
型になっている。MariaDB [world]> SELECT Name, Population / 1000 FROM country WHERE Region = 'Eastern Asia';
+-------------+-------------------+
| Name | Population / 1000 |
+-------------+-------------------+
| China | 1277558.0000 |
| Hong Kong | 6782.0000 |
| Japan | 126714.0000 |
| South Korea | 46844.0000 |
| Macao | 473.0000 |
| Mongolia | 2662.0000 |
| North Korea | 24039.0000 |
| Taiwan | 22256.0000 |
+-------------+-------------------+
8 rows in set (0.00 sec)
SELECT Name, GNP - GNPOld FROM country
WHERE Region = 'Eastern Asia';
MariaDB [world]> SELECT Name, GNP - GNPOld FROM country WHERE Region = 'Eastern Asia';
+-------------+--------------+
| Name | GNP - GNPOld |
+-------------+--------------+
| China | 64549.00 |
| Hong Kong | -7162.00 |
| Japan | -405596.00 |
| South Korea | -121795.00 |
| Macao | -191.00 |
| Mongolia | 110.00 |
| North Korea | NULL |
| Taiwan | -7197.00 |
+-------------+--------------+
8 rows in set (0.00 sec)