Mysql Explain Ïê½â[Ç¿ÁÒÍÆ¼ö]
Mysql Explain Ïê½â
Ò».Óï·¨
explain < table_name >
ÀýÈç: explain select * from t3 where id=3952602;
¶þ.explainÊä³ö½âÊÍ
+----+-------------+-------+-------+-------------------+---------+---------+-------+------+-------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+-------------------+---------+---------+-------+------+-------+
1.id
ÎÒµÄÀí½âÊÇSQLÖ´ÐеÄ˳ÀûµÄ±êʶ,SQL´Ó´óµ½Ð¡µÄÖ´ÐÐ.
ÀýÈç:
mysql> explain select * from (select * from ( select * from t3 where id=3952602) a) b;
+----+-------------+------------+--------+-------------------+---------+---------+------+------+-------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+-------------------+---------+---------+------+------+-------+
| 1 | PRIMARY | <derived2> | system | NULL | NULL | NULL | NULL | 1 | |
| 2 | DERIVED | <derived3> | system | NULL | NULL | NULL | NULL | 1 | |
| 3 | DERIVED | t3 | const | PRIMARY,idx_t3_id | PRIMARY | 4 | | 1 | |
+----+-------------+------------+--------+-------------------+---------+---------+------+------+-------+
ºÜÏÔÈ»ÕâÌõSQLÊÇ´ÓÀïÏòÍâµÄÖ´ÐÐ,¾ÍÊÇ´Óid=3 ÏòÉÏÖ´ÐÐ.
2. select_type
¾ÍÊÇselectÀàÐÍ,¿ÉÒÔÓÐÒÔϼ¸ÖÖ
(1) SIMPL
Ïà¹ØÎĵµ£º
mysqlÊý¾Ý¿âµ¼³öÒªÓõ½MySQLµÄmysqldump¹¤¾ß£¬»ù±¾Ó÷¨ÊÇ£º
shell> mysqldump [OPTIONS] database [tables]
Èç¹ûÄã²»¸ø¶¨ÈÎºÎ±í£¬Õû¸öÊý¾Ý¿â½«±»µ¼³ö¡£
ͨ¹ýÖ´ÐÐmysqldump --help£¬ÄãÄܵõ½ÄãmysqldumpµÄ°æ±¾Ö§³ÖµÄÑ¡Ïî±í¡£
×¢Ò⣬Èç¹ûÄãÔËÐÐmysqldumpûÓÐ--quick»ò--optÑ¡Ïmysq ......
mysql error number 2003
Can't connect to MySQL server xxx.xxx.xxx.xxx (10061)
ÔÚubuntu 9.04ÖÐĬÈϰ²×°ÁËmysql£¬Ä¬ÈÏÖ»Äܱ¾µØ·ÃÎÊ£¬googleÁËһϣº
²ÉÓÃ
µÇ¼µ½MySQL·þÎñÆ÷¶Ë£¬ÔÚmysql¿âÏÂÖ´ÐÐ
grant all on *.* to 'remote'@'172.16.21.39' identified by 'password';
¼´¿É
Èç¹ûÒªÉèÖÃÎ ......
InnoDB¸ÅÊö
InnoDB¸øMySQLÌṩÁ˾ßÓÐÌá½»£¬»Ø¹öºÍ±ÀÀ£»Ö¸´ÄÜÁ¦µÄÊÂÎñ°²È«£¨ACID¼æÈÝ£©´æ´¢ÒýÇæ¡£InnoDBËø¶¨ÔÚÐм¶²¢ÇÒÒ²ÔÚSELECTÓï¾äÌṩһ¸öOracle·ç¸ñÒ»ÖµķÇËø¶¨¶Á¡£ÕâÐ©ÌØÉ«Ôö¼ÓÁ˶àÓû§²¿ÊðºÍÐÔÄÜ¡£Ã»ÓÐÔÚInnoDBÖÐÀ©´óËø¶¨µÄÐèÒª£¬ÒòΪÔÚInnoDBÖÐÐм¶Ëø¶¨ÊʺϷdz£Ð¡µÄ¿Õ¼ä¡£InnoDBÒ²Ö§³ÖFOREIGN KEYÇ¿ÖÆ¡£ÔÚSQL²éÑ¯Ö ......
¡¡ÎÒÃǰÑÏÂÔØµÄÈý¸öÈí¼þ°ü·Åµ½/var/localĿ¼Ï£¨ÕâÊDZÊÕ߸öÈ˵Äϰ¹ß£©£¬ËüÃǶ¼ÊÇtar.gz°ü£¬¿ÉÒÔÓÃÃüÁîtar -xzpvf °üÃû£¬°ÑËüÃÇÔÚµ±Ç°Ä¿Â¼£¨/var/local/£©Öн⿪£º
cd /var/local
tar -xzpvf mysql-4.0.15.tar.gz
tar -xzpvf php-4.3.3.tar.gz
tar -xzpvf httpd-2.0.47.tar.gz
¡¡¡¡½â°üºó¿ÉÒÔ¿ªÊ¼½øÈëÕýʽ°²×°¡£ ......
2009-12-08 18:53
sql½Å±¾Êǰüº¬Ò»µ½¶à¸ösqlÃüÁîµÄsqlÓï¾ä£¬ÎÒÃÇ¿ÉÒÔ½«ÕâЩsql½Å±¾·ÅÔÚÒ»¸öÎı¾ÎļþÖУ¨ÎÒÃdzÆÖ®Îª“sql½Å±¾Îļþ”£©£¬È»ºóͨ¹ýÏà¹ØµÄÃüÁîÖ´ÐÐÕâ¸ösql½Å±¾Îļþ¡£»ù±¾²½ÖèÈçÏ£º
1¡¢´´½¨°üº¬sqlÃüÁîµÄsql½Å±¾Îļþ
ÎļþÖаüº¬Ò»Ð©ÁеÄsqlÓï¾ä£¬Ã¿ÌõÓï¾ä×îºóÒÔ;½á⣬ÎļþÄÚÈÝʾÀýÈçÏ£º
--´´½ ......