mysql-database and data table structure and operation

1. Database system: A database system is a system tool for maintaining and managing databases, and the database system has its own user name and password

1.1. Display the database in the system:show databases;

1.2. Creating database: Create databases;

1.3. Delete a database in the system:drop Database name

Table 2.MySql: In MySQL relational database, the table is the most basic unit, in each data table mainly consists of the following parts: Table name, list, column data type, column constraints.

The actions for a table are as follows:

2.1. Creation of data tables:

  create table table name ([ integrity constraints         Property name data type [ integrity constraints ,
       :
        attribute name data table [ Integrity constraints
 );

  2.2. Data type: Data type in the previous section, it is not verbose again.

  2.3. Column constraint:

2.3.1. PRIMARY key: PRIMARY KEY constraint

2.3.2.foreign key: FOREIGN KEY constraint

     2.3.3. not null: null constraint, the column field cannot be empty

     2.3.4. unique: Unique constraint that indicates that the field value is unique

     2.3.5. Auto_increment: Self-growing,

     2.3.6.default: Default value

3. View the structure of the table:

 3.1. describe (DESC): View the structure of the table

 3.2. show CREATE table: View the structure of the table, including the SQL statement

4. Modify the structure of a table

 4.1. Modify table name:  alter table old table name renmae new table name

 4.2. Add column field:  alter table table name add 1 data type [ integrity constraints ] [First | After 2]---First: Indicates that the data is inserted in the top row of the table, After  property name   2: Insert data after a row

 4.3. Modify column fields:  alter table table name change old property name new property name new data type

 4.4. Delete Column: alter Table drop property name

5. Delete table: delete table drop table table name

 

Note: The above content is only to provide a way of learning, in the actual development of the proposed use of image interface, directly on the above operation, greatly improve the efficiency.

mysql-database and data table structure and operation