Spring boot data jpa APPLICATION FAILED TO START - spring-data-jpa

Question

I learn JPA from https://spring.io/guides/gs/accessing-data-jpa/#initial and git clone project
I did a java file following this example but it is still error.
How can I fix it?
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Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-06-09 16:41:37.706 ERROR 18872 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter :
APPLICATION FAILED TO START
Description:
Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
Reason: Failed to determine a suitable driver class
Action:
Consider the following:
If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).
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pom.xml file
http://maven.apache.org/maven-v4_0_0.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
4.0.0
<groupId>org.springframework</groupId>
<artifactId>gs-accessing-data-jpa</artifactId>
<version>0.1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.2.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</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>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/libs-release</url>
</repository>
<repository>
<id>org.jboss.repository.releases</id>
<name>JBoss Maven Release Repository</name>
<url>https://repository.jboss.org/nexus/content/repositories/releases</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/libs-release</url>
</pluginRepository>
</pluginRepositories>

Answer 1

You used spring-boot-starter-data-jpa in your pom.xml. But I guess, no data source adjusted in appllication.properties file. If you wanna use DB connections, application.properties file should contain configurations like this:
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=mysqluser
spring.datasource.password=mysqlpass
spring.datasource.url=jdbc:mysql://localhost:8080/myDb?createDatabaseIfNotExist=true
Otherwise if you don't use jpa, remove spring-boot-starter-data-jpa dependency from pom.xml:
remove:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
And then try again to run the application.