mysql 学习----> 查看引擎、myisam引擎、自增长、主外键关联、memory引擎、merge引擎

 1.查看引擎
 mysql> show variables like 'table_type';

 mysql> show engines \G
 *************************** 1. row ***************************
       Engine: InnoDB
      Support: DEFAULT
      Comment: Supports transactions, row-level locking, and foreign keys
 Transactions: YES
           XA: YES
   Savepoints: YES
 *************************** 2. row ***************************
       Engine: PERFORMANCE_SCHEMA
      Support: YES
      Comment: Performance Schema
 Transactions: NO
           XA: NO
   Savepoints: NO
 *************************** 3. row ***************************
       Engine: MRG_MYISAM
      Support: YES
      Comment: Collection of identical MyISAM tables
 Transactions: NO
           XA: NO
   Savepoints: NO
 *************************** 4. row ***************************
       Engine: CSV
      Support: YES
      Comment: CSV storage engine
 Transactions: NO
           XA: NO
   Savepoints: NO
 *************************** 5. row ***************************
       Engine: MyISAM
      Support: YES
      Comment: MyISAM storage engine
 Transactions: NO
           XA: NO
   Savepoints: NO
 *************************** 6. row ***************************
       Engine: MEMORY
      Support: YES
      Comment: Hash based, stored in memory, useful for temporary tables
 Transactions: NO
           XA: NO
   Savepoints: NO


 mysql> show variables like 'have%';
 +----------------------+-------+
 | Variable_name        | Value |
 +----------------------+-------+
 | have_compress        | YES   |
 | have_crypt           | YES   |
 | have_csv             | YES   |
 | have_dynamic_loading | YES   |
 | have_geometry        | YES   |
 | have_innodb          | YES   |
 | have_ndbcluster      | NO    |
 | have_openssl         | NO    |
 | have_partitioning    | YES   |
 | have_profiling       | YES   |
 | have_query_cache     | YES   |
 | have_rtree_keys      | YES   |
 | have_ssl             | NO    |
 | have_symlink         | YES   |
 +----------------------+-------+

 2.myisam引擎相关
 mysql> use test1;
 Database changed
 mysql> create table ai(
     -> i bigint(20) not null auto_increment,
     -> primary key(i)
     -> ) engine=myisam default charset=gbk;

 mysql> create table country(
     -> country_id smallint unsigned not null auto_increment,
     -> country varchar(50) not null,
     -> last_update timestamp not null default current_timestamp on update current_timestamp, primary key(country_id)
     -> ) engine = innodb default charset=gbk;

 mysql> alter table ai engine = innodb;

 mysql> show create table ai \G;
 *************************** 1. row ***************************
        Table: ai
 Create Table: CREATE TABLE `ai` (
   `i` bigint(20) NOT NULL AUTO_INCREMENT,
   PRIMARY KEY (`i`)
 ) ENGINE=InnoDB DEFAULT CHARSET=gbk

 ERROR:
 No query specified

 mysql> create table myisam_char(name char(10)) engine=myisam;
 Query OK, 0 rows affected (0.01 sec)

 mysql> insert into myisam_char values('abcde'),('abcde    '),('       abcde'),('       abcde        ');


 mysql> select name,length(name) from myisam_char;
 +------------+--------------+
 | name       | length(name) |
 +------------+--------------+
 | abcde      |            5 |
 | abcde      |            5 |
 |        abc |           10 |
 |        abc |           10 |
 +------------+--------------+

 mysql> truncate myisam_char;

 mysql> select * from myisam_char;

 mysql> insert into myisam_char values
     -> ('abcde'),
     -> ('abcde  '),
     -> ('  abcde'),
     -> ('  abcde  ');

 mysql> select * from myisam_char;
 +---------+
 | name    |
 +---------+
 | abcde   |
 | abcde   |
 |   abcde |
 |   abcde |
 +---------+

 mysql> select name,length(name) from myisam_char;
 +---------+--------------+
 | name    | length(name) |
 +---------+--------------+
 | abcde   |            5 |
 | abcde   |            5 |
 |   abcde |            7 |
 |   abcde |            7 |
 +---------+--------------+

 3.自增长
 mysql> use test1;
 Reading table information for completion of table and column names
 You can turn off this feature to get a quicker startup with -A

 Database changed
 mysql> create table autoincre_demo
     -> ( i smallint not null auto_increment,
     -> name varchar(10),primary key(i)
     -> ) engine = innodb;

 mysql> insert into autoincre_demo values(1,'1'),(0,'2'),(null,'3');


 mysql> select * from autoincre_demo;
 +---+------+
 | i | name |
 +---+------+
 | 1 | 1    |
 | 2 | 2    |
 | 3 | 3    |
 +---+------+

 mysql> insert into autoincre_demo values(4,'4');

 mysql> select last_insert_id();
 +------------------+
 | last_insert_id() |
 +------------------+
 |                2 |
 +------------------+

 mysql> insert into autoincre_demo(name) values('5'),('6'),('7');

 mysql> select last_insert_id();
 +------------------+
 | last_insert_id() |
 +------------------+
 |                5 |
 +------------------+

 mysql> alter table autoincre_demo rename autoincre_demo_old;

 mysql> create table autoincre_demo (d1 smallint not null auto_increment, d2 smallint not null, name varchar(10), index(d2,d1) ) engine = myisam;


 mysql> insert into autoincre_demo (d2,name) values (2,'2'), (3,'3'), (4,'4'), (2,'2'), (3,'3'), (4,'4');

 mysql> select * from autoincre_demo;
 +----+----+------+
 | d1 | d2 | name |
 +----+----+------+
 |  1 |  2 | 2    |
 |  1 |  3 | 3    |
 |  1 |  4 | 4    |
 |  2 |  2 | 2    |
 |  2 |  3 | 3    |
 |  2 |  4 | 4    |
 +----+----+------+

 4.主外键关联
 mysql> alter table country rename country_old;

 mysql> create table country( country_id smallint unsigned not null auto_increment, country varchar(50) not null, last_update timestamp not null default current_timestamp on update current_timestamp, primary key( country_id) ) engine = innodb default charset=utf8;

 mysql> create table city(
     -> city_id smallint unsigned not null auto_increment,
     -> city varchar(50) not null, country_id smallint unsigned not null,
     -> last_update timestamp not null default current_timestamp on update current_timestamp,
     -> primary key(city_id), key idx_fk_country_id(country_id),
     -> constraint fk_city_country foreign key(country_id) references country(country_id)  on delete restrict on update cascade
     -> ) engine = innodb default charset=utf8;

 mysql> insert into country(country_id,country) values (1,'tom');

 mysql> select * from country where country_id =1;
 +------------+---------+---------------------+
 | country_id | country | last_update         |
 +------------+---------+---------------------+
 |          1 | tom     | 2015-10-02 20:48:15 |
 +------------+---------+---------------------+

 mysql> insert into city(city_id,city,country_id) values ('251','bill',1);

 mysql> select * from city where country_id = 1;
 +---------+------+------------+---------------------+
 | city_id | city | country_id | last_update         |
 +---------+------+------------+---------------------+
 |     251 | bill |          1 | 2015-10-02 20:48:51 |
 +---------+------+------------+---------------------+

 mysql> update country set country_id = 10000 where country_id = 1;

 mysql> select * from country where country='tom';
 +------------+---------+---------------------+
 | country_id | country | last_update         |
 +------------+---------+---------------------+
 |      10000 | tom     | 2015-10-02 20:49:29 |
 +------------+---------+---------------------+

 mysql> select * from city where city_id = 251;
 +---------+------+------------+---------------------+
 | city_id | city | country_id | last_update         |
 +---------+------+------------+---------------------+
 |     251 | bill |      10000 | 2015-10-02 20:48:51 |
 +---------+------+------------+---------------------+

 mysql> show table status like 'city' \G
 *************************** 1. row ***************************
            Name: city
          Engine: InnoDB
         Version: 10
      Row_format: Compact
            Rows: 1
  Avg_row_length: 16384
     Data_length: 16384
 Max_data_length: 0
    Index_length: 16384
       Data_free: 0
  Auto_increment: 252
     Create_time: 2015-10-02 20:47:27
     Update_time: NULL
      Check_time: NULL
       Collation: utf8_general_ci
        Checksum: NULL
  Create_options:
         Comment:

 mysql> show table status like 'country' \G
 *************************** 1. row ***************************
            Name: country
          Engine: InnoDB
         Version: 10
      Row_format: Compact
            Rows: 1
  Avg_row_length: 16384
     Data_length: 16384
 Max_data_length: 0
    Index_length: 0
       Data_free: 0
  Auto_increment: 2
     Create_time: 2015-10-02 20:42:25
     Update_time: NULL
      Check_time: NULL
       Collation: utf8_general_ci
        Checksum: NULL
  Create_options:
         Comment:

 mysql> desc country;
 +-------------+----------------------+------+-----+-------------------+-----------------------------+
 | Field       | Type                 | Null | Key | Default           | Extra                       |
 +-------------+----------------------+------+-----+-------------------+-----------------------------+
 | country_id  | smallint(5) unsigned | NO   | PRI | NULL              | auto_increment              |
 | country     | varchar(50)          | NO   |     | NULL              |                             |
 | last_update | timestamp            | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
 +-------------+----------------------+------+-----+-------------------+-----------------------------+

 mysql> select * from city;
 +---------+------+------------+---------------------+
 | city_id | city | country_id | last_update         |
 +---------+------+------------+---------------------+
 |     251 | bill |      10000 | 2015-10-02 20:48:51 |
 +---------+------+------------+---------------------+

 5.memory引擎
 mysql> create table tab_memory engine = memory  select city_id,city,country_id from city group by city_id;

 mysql> select count(*) from tab_memory;
 +----------+
 | count(*) |
 +----------+
 |        1 |
 +----------+

 mysql> show table status like 'tab_memory' \G
 *************************** 1. row ***************************
            Name: tab_memory
          Engine: MEMORY
         Version: 10
      Row_format: Fixed
            Rows: 1
  Avg_row_length: 155
     Data_length: 127040
 Max_data_length: 32505825
    Index_length: 0
       Data_free: 0
  Auto_increment: NULL
     Create_time: 2015-10-02 20:53:16
     Update_time: NULL
      Check_time: NULL
       Collation: utf8_general_ci
        Checksum: NULL
  Create_options:
         Comment:

 mysql> create index mem_hash using hash on tab_memory(city_id);

 mysql> show index from tab_memory \G;
 *************************** 1. row ***************************
         Table: tab_memory
    Non_unique: 1
      Key_name: mem_hash
  Seq_in_index: 1
   Column_name: city_id
     Collation: NULL
   Cardinality: 0
      Sub_part: NULL
        Packed: NULL
          Null:
    Index_type: HASH
       Comment:
 Index_comment:

 ERROR:
 No query specified

 mysql> drop index mem_hash on tab_memory;

 mysql> create index mem_hash using btree on tab_memory(city_id);

 mysql> show index from tab_memory \G
 *************************** 1. row ***************************
         Table: tab_memory
    Non_unique: 1
      Key_name: mem_hash
  Seq_in_index: 1
   Column_name: city_id
     Collation: A
   Cardinality: NULL
      Sub_part: NULL
        Packed: NULL
          Null:
    Index_type: BTREE
       Comment:
 Index_comment:

 6.merge引擎
 mysql> use test1;
 Reading table information for completion of table and column names
 You can turn off this feature to get a quicker startup with -A

 Database changed
 mysql> create table payment_2006( country_id smallint, payment_date datetime, amount decimal(15,2), key idx_fk_country_id(country_id) )engine=myisam;

 mysql> create table payment_2007( country_id smallint, payment_date datetime, amount decimal(15,2), key idx_fk_country_id(country_id) )engine=myisam;

 mysql> create table payment_all(
     -> country_id smallint,
     -> payment_date datetime,
     -> amount decimal(15,2),
     -> index(country_id)
     -> )engine=merge union=(payment_2006,payment_2007) insert_method=last;

 mysql> insert into payment_2006
     -> values(1,'2006-05-01',100000),
     -> (2,'2006-08-15',150000);

 mysql> insert into payment_2007
     -> values(1,'2007-02-20',35000),
     -> (2,'2007-07-15',220000);

 mysql> select * from payment_2006;
 +------------+---------------------+-----------+
 | country_id | payment_date        | amount    |
 +------------+---------------------+-----------+
 |          1 | 2006-05-01 00:00:00 | 100000.00 |
 |          2 | 2006-08-15 00:00:00 | 150000.00 |
 +------------+---------------------+-----------+

 mysql> select * from payment_2007;
 +------------+---------------------+-----------+
 | country_id | payment_date        | amount    |
 +------------+---------------------+-----------+
 |          1 | 2007-02-20 00:00:00 |  35000.00 |
 |          2 | 2007-07-15 00:00:00 | 220000.00 |
 +------------+---------------------+-----------+

 mysql> select * from payment_all;
 +------------+---------------------+-----------+
 | country_id | payment_date        | amount    |
 +------------+---------------------+-----------+
 |          1 | 2006-05-01 00:00:00 | 100000.00 |
 |          2 | 2006-08-15 00:00:00 | 150000.00 |
 |          1 | 2007-02-20 00:00:00 |  35000.00 |
 |          2 | 2007-07-15 00:00:00 | 220000.00 |
 +------------+---------------------+-----------+

 mysql> insert into payment_all
     -> values(3,'2006-03-31',112200);

 mysql> select * from payment_all;
 +------------+---------------------+-----------+
 | country_id | payment_date        | amount    |
 +------------+---------------------+-----------+
 |          1 | 2006-05-01 00:00:00 | 100000.00 |
 |          2 | 2006-08-15 00:00:00 | 150000.00 |
 |          1 | 2007-02-20 00:00:00 |  35000.00 |
 |          2 | 2007-07-15 00:00:00 | 220000.00 |
 |          3 | 2006-03-31 00:00:00 | 112200.00 |
 +------------+---------------------+-----------+

 mysql> select * from payment_2007;
 +------------+---------------------+-----------+
 | country_id | payment_date        | amount    |
 +------------+---------------------+-----------+
 |          1 | 2007-02-20 00:00:00 |  35000.00 |
 |          2 | 2007-07-15 00:00:00 | 220000.00 |
 |          3 | 2006-03-31 00:00:00 | 112200.00 |
 +------------+---------------------+-----------+