1. sql constrains
2. sql concept
3. sql syntax
4. sql expression
5. sql operator
```mysql -u root -h localhost mysql -u root -h localhost -p -u: is username -h: is host -P: is password mysql> show engines -> ; +--------------------+---------+------------------------------------------------------------+--------------+------+------------+ | Engine | Support | Comment | Transactions | XA | Savepoints | +--------------------+---------+------------------------------------------------------------+--------------+------+------------+ | CSV | YES | CSV storage engine | NO | NO | NO | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | +--------------------+---------+------------------------------------------------------------+--------------+------+------------+ 6 rows in set (0.00 sec)
<h3>mysqldump learn</h3>
pwd:current directory
mysqldump -u root -h localhost school>/Users/liuzheng/youku/lisa/sql_learn/school.sql
-u:is username -h:is host -p: passowrd
从定向 语法： database > database.sql