MySQL 全文检索

不是所有的数据表都支持全文检索 MySQL支持多种底层数据库引擎，但是并非所有的引擎支持全文检索 ，目前最常用引擎是是MyISAM和InnoDB；前者支持全文检索，后者不支持。

实验： 

表productnotes ：

1.查询包含rabbit的行，并按照相关性排序

mysql> SELECT note_text
    -> FROM productnotes
    -> WHERE Match(note_text) Against('rabbit');
+----------------------------------------------------------------------------------------------------------------------+
| note_text                                                                                                            |
+----------------------------------------------------------------------------------------------------------------------+
| Customer complaint: rabbit has been able to detect trap, food apparently less effective now.                         |
| Quantity varies, sold by the sack load. All guaranteed to be bright and orange, and suitable for use as rabbit bait. |
+----------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.01 sec)

 2.显示每一条的相关性值

mysql> SELECT note_text,
    ->  Match(note_text) Against('rabbit') AS match_rank
    -> FROM productnotes;
+-----------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------+
| note_text                                                                                                                                                 | match_rank         |
+-----------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------+
| Customer complaint:
Sticks not individually wrapped, too easy to mistakenly detonate all at once.
Recommend individual wrapping.                          |                  0 |
| Can shipped full, refills not available.
Need to order new can if refill needed.                                                                          |                  0 |
| Safe is combination locked, combination not provided with safe.
This is rarely a problem as safes are typically blown up or dropped by customers.         |                  0 |
| Quantity varies, sold by the sack load.
All guaranteed to be bright and orange, and suitable for use as rabbit bait.                                      | 1.5905543565750122 |
| Included fuses are short and have been known to detonate too quickly for some customers.
Longer fuses are available (item FU1) and should be recommended. |                  0 |
| Matches not included, recommend purchase of matches or detonator (item DTNTR).                                                                            |                  0 |
| Please note that no returns will be accepted if safe opened using explosives.                                                                             |                  0 |
| Multiple customer returns, anvils failing to drop fast enough or falling backwards on purchaser. Recommend that customer considers using heavier anvils.  |                  0 |
| Item is extremely heavy. Designed for dropping, not recommended for use with slings, ropes, pulleys, or tightropes.                                       |                  0 |
| Customer complaint: rabbit has been able to detect trap, food apparently less effective now.                                                              | 1.6408053636550903 |
| Shipped unassembled, requires common tools (including oversized hammer).                                                                                  |                  0 |
| Customer complaint:
Circular hole in safe floor can apparently be easily cut with handsaw.                                                                |                  0 |
| Customer complaint:
Not heavy enough to generate flying stars around head of victim. If being purchased for dropping, recommend ANV02 or ANV03 instead.   |                  0 |
| Call from individual trapped in safe plummeting to the ground, suggests an escape hatch be added.
Comment forwarded to vendor.                            |                  0 |
+-----------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------+
14 rows in set (0.00 sec)

3.有heavy 但是没有rope

mysql> SELECT note_text
    -> FROM productnotes
    -> WHERE Match(note_text)
    ->  Against('heavy -rope*' IN BOOLEAN MODE);
+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| note_text                                                                                                                                               |
+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| Customer complaint:
Not heavy enough to generate flying stars around head of victim. If being purchased for dropping, recommend ANV02 or ANV03 instead. |
+---------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)