sennaの使い方がよくわかりません！→わかりました！

mysql> select count(*) from job;
+----------+
| count(*) |
+----------+
|     3093 | 
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from job where match ( free_word_text ) against ('自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|      520 | 
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from job where match ( free_word_text ) against ('電気' in boolean mode);
+----------+
| count(*) |
+----------+
|      448 | 
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from job where match ( free_word_text ) against ('電気 +自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|      168 | 
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from job where match ( free_word_text ) against ('電気 自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|      800 | 
+----------+
1 row in set (0.00 sec)

というときに、電気も自動車も含まない2293件を出す方法がわかりません！

mysql> select count(*) from job where match ( free_word_text ) against ('-電気 -自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|      280 | 
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from job where match ( free_word_text ) against ('-電気 自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|      800 | 
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from job where match ( free_word_text ) against ('-電気 +自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|      168 | 
+----------+
1 row in set (0.00 sec)

という挙動を見ると、一個目に「-」をつけても無視されてるみたいな気がします。どうすればいいんでしょう？

追記

2008年07月09日 kazuhooku where NOT match 〜 って書けなかったっけ

うは！たしかにたしかに！あざーっす！

mysql> select count(*) from job where not match(free_word_text) against ('電気  自動車' in boolean mode);
+----------+
| count(*) |
+----------+
|     2293 | 
+----------+
1 row in set (0.04 sec)

できた！senna関係ないところでポカってましたね。

→でも一個目の「-」も理解してほしいなぁ。