²é¿´ MySql ×Ö·û¼¯
MySQL ÂÒÂëµÄ¸ùÔ´ÊÇµÄ MySQL ×Ö·û¼¯ÉèÖò»µ±µÄÎÊÌ⣬±¾ÎÄ»ã×ÜÁËÓйز鿴 MySQL ×Ö·û¼¯µÄÃüÁî¡£°üÀ¨²é¿´ MySQL Êý¾Ý¿â·þÎñÆ÷×Ö·û¼¯¡¢²é¿´ MySQL Êý¾Ý¿â×Ö·û¼¯£¬ÒÔ¼°Êý¾Ý±íºÍ×ֶεÄ×Ö·û¼¯¡¢µ±Ç°°²×°µÄ MySQL ËùÖ§³ÖµÄ×Ö·û¼¯µÈ¡£
Ò»¡¢²é¿´ MySQL Êý¾Ý¿â·þÎñÆ÷ºÍÊý¾Ý¿â×Ö·û¼¯¡£
mysql> show variables like '%char%';
+--------------------------------+-----------------------------------------------+------
| Variable_name | Value |......
+--------------------------------+-------------------------------------+------
| character_set_client | utf8 |...... -- ¿Í»§¶Ë×Ö·û¼¯
| character_set_connection| utf8 |......
| character_set_database | utf8 |...... -- Êý¾Ý¿â×Ö·û¼¯
| character_set_filesystem | binary |......
| character_set_results | utf8 |......
| character_set_server | utf8 |...... -- ·þÎñÆ÷×Ö·û¼¯
| character_set_system | utf8 |......
| character_sets_dir | D:\MySQL Server 5.0\share\charsets\ |......
+--------------------------+-------------------------------------+------
¶þ¡¢²é¿´ MySQL Êý¾Ý±í£¨table£© µÄ×Ö·û¼¯¡£
mysql> show table status from sqlstudy_db like '%countries%';
+-----------+--------+---------+------------+------+-----------------+------
| Name | Engine | Version | Row_format | Rows | Collation |......
+-----------+--------+---------+------------+------+-----------------+------
| countries | InnoDB | 10 | Compact | 11 | utf8_general_ci |......
+-----------+--------+---------+------------+------+-----------------+------
Èý¡¢²é¿´ MySQL Êý¾ÝÁУ¨column£©µÄ×Ö·û¼¯¡£
mysql> show full columns from countries;
+----------------------+-------------+-----------------+--------
| Field | Type | Collation
Ïà¹ØÎĵµ£º
information_schema¿âÖаüº¬Á˶ÔÕû¸öÊý¾Ý¿âµÄºÜ¶àͳ¼ÆÐÅÏ¢£¬¿ÉÒÔͨ¹ý²é¿´ËüÃÇ£¬À´µÃµ½Êý¾Ý¿âÏà¹ØµÄÐÅÏ¢¡£
mysql> use information_schema;
Database changed
mysql> select count(1) as tables, concat(round(sum(table_rows)/1000000,2),'M') as rows, concat(round(sum(data_length)/(1024*1024*1024),2),'G') a ......
½â¾ö·½·¨£º
1¡¢¹Ø±ÕÊý¾Ý¿âÁ¬½Ó;
2¡¢ÓÒ»÷Êý¾Ý¿âÑ¡Ôñ“Á¬½ÓÊôÐÔ”£»
3¡¢Ñ¡Ôñ“¸ß¼¶”ÊôÐÔÒ³£¬½«“ʹÓÃMySQL×Ö·û¼¯”µÄ¹´È¥µô£¬²¢Ñ¡Ôñ“±àÂë”Ϊ“936 (ANSI/OEM - Simplified Chinese GBK)”
4¡¢¹Ø±Õ±£´æ£¬ÖØÐÂÁ¬½Ó¡£ ......
¡¡¡¡¿Í»§ÓõÄÊý¾Ý¿âÊÇmysql£¬¶øÑз¢ºÃµÄ²úÆ·Ö§³Öoracle£¬ÎªÁËÈÿͻ§ÌÍÑü°ü£¬ÎÒÃDZØÐë°ÑÊý¾Ý¿â»·¾³´ÓoracleתÏòmysql¡£ÎÒÃÇÔÚת»»µÄ¹ý³ÌÖÐÅöµ½ÁËÏÂÃæÒ»Ð©ÎÊÌ⣬ϣÍûÄܸøÍ¬ÑùÔâÓöµÄͬÈÊÃÇһЩ½è¼ø¡£Èç¹ûÎÒÃÇÔÚ×î³õµÄÉè¼Æ¡¢±àÂë¹ý³ÌÖÐ×¢ÒâÊý¾Ý¿âµÄÒÆÖ²ÐÔ£¬ÕâÖÖÇé¿öÏ¿ÉÒÔÍêÈ«²»ÐèÒª×÷¶îÍ⹤×÷¡£
¡¡¡¡Ò»¡¢Êý¾Ý¿â»·¾³´Óoracleת ......
MYSQL »ñÈ¡µ±Ç°ÈÕÆÚ¼°ÈÕÆÚ¸ñʽ
»ñȡϵͳÈÕÆÚ£º NOW()
¸ñʽ»¯ÈÕÆÚ£º DATE_FORMAT(date, format)
×¢£º date£ºÊ±¼ä×Ö¶Î
  ......
²éѯ¼°É¾³ýÖØ¸´¼Ç¼µÄ·½·¨
(Ò»)
1¡¢²éÕÒ±íÖжàÓàµÄÖØ¸´¼Ç¼£¬Öظ´¼Ç¼ÊǸù¾Ýµ¥¸ö×ֶΣ¨peopleId£©À´ÅжÏ
select * from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2¡¢É¾³ý±íÖжàÓàµÄÖØ¸´¼Ç¼£¬Öظ´¼Ç¼ÊǸù¾Ýµ¥¸ö×ֶΣ¨peopleId£©À´Åжϣ¬Ö»Á ......