Learn "MYSQL" course, date 2017.4.25-2017.4.30

To display the database:

SHOW DATABASES database_name;

To create a database:

CREATE DATABASES database_name;

To delete a database:

DROP DATABASE database_name;

To create a data table:

CREATE table< Table name >

(

Field name 1, data type [column-level constraint] [default],

);

Cases:

CREATE TABLE TB1

(ID INT (11),

NAME VARCHAR (20));

Primary key: Field name data type PRIMARY key[default value];

Cases:

CREATE TABLE TB1

(ID INT (one) PRIMARY KEY,

NAME VARCHAR (20));

Or:

CREATE TABLE TB1

(ID INT (11),

NAME VARCHAR (20)

PRIMARY KEY (ID));

FOREIGN key:

[constraint< foreign key Name >] FOREIGN KEY field name 1[field Name 2]

preferences< primary Table name > Primary key column 1[primary key column 2]

Example: (Associating DeptID as a foreign key to Tb_2 's primary key ID)

CREATE TABLE tb_1

(

ID INT (one) PRIMARY KEY,

Name VARCHAR () not NULL (non-NULL),

Location VARCHAR (50)

);

CREATE TABLE tb_2

(

ID INT (one) PRIMARY KEY,

Name VARCHAR (20),

DeptID INT (11),

CONSTRAINT tb_1 FOREIGN KEY (deptid) REFERENCES tb_2 (id));

Set the property value of the table to automatically increase:

Field name data type Auto_increment

Cases:

ID INT (one) PRIMARY KEY auto_increment,

Modify Table Name:

ALTER table< Old table name >RENAME[TO]< new table name >

ALTER TABLE tb_1 RENAME tb_dept;

Modify Table Contents:

ALTER table< table name >MODIFY< field name >< data type >

ALTER TABLE tb_1 MODIFY name VARCHAR (30);

Learn "MYSQL" course, date 2017.4.25-2017.4.30