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 |

+------------+---------------------+-----------+