java - Schema 'SA' does not exist and dropping table -

i using spring boot create courses , topics database. having trouble bunch of errors showed once made changes courses classes. not sure what's wrong. here error messages:

 error 1136 --- [           main] org.hibernate.tool.hbm2ddl.schemaexport  : hhh000389: unsuccessful: alter table course drop constraint fkokaxyfpv8p583w8yspapfb2ar      error 1136 --- [           main] org.hibernate.tool.hbm2ddl.schemaexport  : schema 'sa' not exist      error 1136 --- [           main] org.hibernate.tool.hbm2ddl.schemaexport  : hhh000389: unsuccessful: drop table course      error 1136 --- [           main] org.hibernate.tool.hbm2ddl.schemaexport  : schema 'sa' not exist      error 1136 --- [           main] org.hibernate.tool.hbm2ddl.schemaexport  : hhh000389: unsuccessful: drop table topic      error 1136 --- [           main] org.hibernate.tool.hbm2ddl.schemaexport  : schema 'sa' not exist      warn 1136 --- [           main] o.h.engine.jdbc.spi.sqlexceptionhelper   : sql warning code: 10000, sqlstate: 01j01      warn 1136 --- [           main] o.h.engine.jdbc.spi.sqlexceptionhelper   : 

database 'memory:testdb' not created, connection made existing database instead.

also, here course code, topics code alright think having trouble this. using internal database.

package ...

@entity  public class course {     // here generate constructors , getters/setters     @id     private string id;     private string name;     private string description;      @manytoone     private topic topic; //use tie class topic class, make easier user      public topic gettopic() {         return topic;     }      public void settopic(topic topic) {         this.topic = topic;     }      public course() {     }      public course(string id, string name, string description, string topicid) {         super();         this.id = id;         name = name;         this.description = description;         this.topic = new topic(topicid,"","");     }      public string getid() {         return id;     }     public void setid(string id) {         this.id = id;     }     public string getname() {         return name;     }     public void setname(string name) {         name = name;     }     public string getdescription() {         return description;     }     public void setdescription(string description) {         this.description = description;     } } 

also controller:

@restcontroller() //makes rest controller, every time build class , add on top of public class coursecontroller {      @autowired // marks courseservice needs dependency inj.     private courseservice courseservice;// create service need private courseservice variable      //getall     @requestmapping("/topics/{id}/courses")     public list<course> getallcourses(@pathvariable string id){         return courseservice.getallcourses(id);  //getallcourses topic id     }     //get     @requestmapping("/topics/{topicid}/courses/{id}")       public course getcourse(@pathvariable string id) {         return courseservice.getcourse(id);     }      //post     @requestmapping(method = requestmethod.post, value = "/topics/{topicid}/courses")     public void addcourse(@requestbody course course, @pathvariable string topicid) {          course.settopic(new topic(topicid, "", ""));         courseservice.addcourse(course);     }      //put     @requestmapping(method = requestmethod.put, value = "/topics/{topicid}/courses/{id}")     public void updatecourse(@requestbody course course,  @pathvariable string id,  @pathvariable string topicid) {          course.settopic(new topic(topicid, "", ""));         courseservice.updatecourse(course);      }     //delete     @requestmapping(method = requestmethod.delete, value = "/topics/{topicid}/courses/{id}")     public void deletecourse(@pathvariable string id, @pathvariable string topicid) {         courseservice.deletecourse(id);      } } 

and service class:

package io.msela.springbootstarter.course;  import java.util.arraylist; import java.util.list;  import org.springframework.beans.factory.annotation.autowired; import org.springframework.stereotype.service;  @service public class courseservice {      @autowired // injects courserepository it's initialized     private courserepository courserepository;      public list<course> getallcourses(string topicid){ //getting not good!         list<course> courses = new arraylist<>() ;         courserepository.findbytopicid(topicid).foreach(courses::add);         return courses;     }      public course getcourse(string id) {         return courserepository.findone(id);     }      public void addcourse(course course) {         courserepository.save(course); //save course database             }      public void updatecourse(course course) {         courserepository.save(course);         //save both add , update         }       public void deletecourse(string id) {         courserepository.delete(id);     } } 

edit: here's pom.xml file well

http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4.0.0

<groupid>io.msela</groupid> <artifactid>course-api-data</artifactid> <version>0.0.1-snapshot</version> <packaging>jar</packaging>  <name>course-api-data</name> <description>course api spring data</description>  <parent>     <groupid>org.springframework.boot</groupid>     <artifactid>spring-boot-starter-parent</artifactid>     <version>1.5.4.release</version>     <relativepath/> <!-- lookup parent repository --> </parent>  <properties>     <project.build.sourceencoding>utf-8</project.build.sourceencoding>     <project.reporting.outputencoding>utf-8</project.reporting.outputencoding>     <java.version>1.8</java.version> </properties>  <dependencies>     <dependency>         <groupid>org.springframework.boot</groupid>         <artifactid>spring-boot-starter-data-jpa</artifactid>     </dependency>     <dependency>         <groupid>org.springframework.boot</groupid>         <artifactid>spring-boot-starter-web</artifactid>     </dependency>      <dependency>         <groupid>org.apache.derby</groupid>         <artifactid>derby</artifactid>         <scope>runtime</scope>     </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> 

edit 2

the actual error seems following:

exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.unsatisfieddependencyexception: error creating bean name 'coursecontroller': unsatisfied dependency expressed through field 'courseservice'; nested exception org.springframework.beans.factory.unsatisfieddependencyexception: error creating bean name 'courseservice': unsatisfied dependency expressed through field 'courserepository'; nested exception org.springframework.beans.factory.beancreationexception: error creating bean name 'courserepository': invocation of init method failed; nested exception java.lang.illegalargumentexception: not create query metamodel method public abstract java.util.list io.msela.springbootstarter.course.courserepository.findbyname(java.lang.string)!