（1） Integrating two mapping frameworks of Dao

One .Spring Data JPA （ Bottom hibernate） and MybaTis Comparison of

Both are ORM Mapping framework

1. hibernate It's object-oriented , and MyBatis It's relationship oriented .
2. hibernate convenient 、 More automation , and MyBatis stay Sql Statement writing is more flexible and free
3. Object oriented considers the whole life cycle of an object, including the creation of an object 、 Persistence 、 Changes in state and behavior, etc , Object persistence is just a state of an object , The concept of relational database pays more attention to the efficient storage and reading of data ;
4. Object oriented emphasizes the encapsulation of object state , Object encapsulates its own state （ Or data ） External objects are not allowed to be modified at will , Only some legal behavior methods are exposed for external objects to call ; The relational database is open , Users can read and modify the relationship at will , And can be arbitrarily associated with other tables （ as long as sql If allowed correctly ）;
5. Object oriented dynamic . Relational model , Static

Two .Mysql Storage engine for

2.1 Innodb（5.7 The above defaults to ）：

Conventional ISAM And MyISAM comparison ,InnoDB The most important feature of the company is its support ACID Compatible Business （Transaction） function , Be similar to PostgreSQL.

2.2 MyISAM（5.5 The following defaults ）

2.3 Whether the database is case sensitive ：

The tables in the database are stored on disk in the form of files .

• stay windows in , Files are case insensitive, so , The database is windows Middle is the sense of case ambiguity
• stay linux in , Files are case sensitive , All databases are in linux Case sensitive
• summary ： The database is finally deployed to linux On , So in general, databases are treated as case sensitive .

3、 ... and .SpingData JPA Build table by actual operation

First step , Create a Spring factory , Import dependence

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

The second step , To configure application.properties

spring.datasource.username=root
spring.datasource.password=1234
spring.datasource.url=jdbc:mysql:///test02?serverTimezone=Asia/Shanghai

#  To configure  JPA
#  Configuration database 
spring.jpa.database-platform=mysql
spring.jpa.database=mysql
#  Print on console  SQL
spring.jpa.show-sql=true
#  Whenever the project starts , Automatically check whether the data table and object correspond one by one , If not , Subject to the object , Update data table 
spring.jpa.hibernate.ddl-auto=update
# MyISAM InnoDB  Specify database dialect 
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL57Dialect

The third step , Create entity class User

/** *  adopt  @Entity  Annotation to mark that the current class is an entity class  *  By default , Class name is table name  * *  Can pass  name  Property specifies the name of the table  */
@Data
@Entity(name = "t_user")
public class User {
    
    // Set the current attribute as the primary key 
    @Id
    // Set up  MySQL  The primary key increases automatically 
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    // By default ,username  The fields generated by attributes are also called  username
    // Set field name 、 Create a unique index 、 Set the field length 
    @Column(name = "name",unique = true,length = 32)
    private String username;
    private String address;
}