MySQL SUBSTRING

SUBSTRはSUBSTRINGのシノニム

起点は0じゃなくて1なので

mysql> SELECT SUBSTRING('Quadratically',5);
        -> 'ratically'
mysql> SELECT SUBSTRING('foobarbar' FROM 4);
        -> 'barbar'
mysql> SELECT SUBSTRING('Quadratically',5,6);
        -> 'ratica'
mysql> SELECT SUBSTRING('Sakila', -3);
        -> 'ila'
mysql> SELECT SUBSTRING('Sakila', -5, 3);
        -> 'aki'
mysql> SELECT SUBSTRING('Sakila' FROM -4 FOR 2);
        -> 'ki'

以下やると無になる

mysql> SELECT SUBSTRING('Quadratically',1,6);
+--------------------------------+
| SUBSTRING('Quadratically',1,6) |
+--------------------------------+
| Quadra                         |
+--------------------------------+
1 row in set (0.17 sec)

mysql> SELECT SUBSTRING('Quadratically',0,6);
+--------------------------------+
| SUBSTRING('Quadratically',0,6) |
+--------------------------------+
|                                |
+--------------------------------+
1 row in set (0.03 sec)

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