Duplicate entry '1' for key 'PRIMARY'(报错)

使用MySQL+ibatis进行插入测试的时候，报错：信息如下：

测试插入
com.ibatis.common.jdbc.exception.NestedSQLException:   
--- The error occurred in com/study/ibatis/Student.xml.  
--- The error occurred while applying a parameter map.  
--- Check the addStudent-InlineParameterMap.  
--- Check the statement (update failed).  
--- Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 'PRIMARY'
    at com.ibatis.sqlmap.engine.mapping.statement.MappedStatement.executeUpdate(MappedStatement.java:107)
    at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.insert(SqlMapExecutorDelegate.java:393)
    at com.ibatis.sqlmap.engine.impl.SqlMapSessionImpl.insert(SqlMapSessionImpl.java:82)
    at com.ibatis.sqlmap.engine.impl.SqlMapClientImpl.insert(SqlMapClientImpl.java:58)
    at com.study.ibatis.StudentDaoImpl.addStudent(StudentDaoImpl.java:33)
    at com.study.ibatis.TestIbatis.main(TestIbatis.java:14)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 'PRIMARY'
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
    at com.mysql.jdbc.Util.getInstance(Util.java:381)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1015)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3491)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3423)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734)
    at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:995)
    at com.ibatis.sqlmap.engine.execution.SqlExecutor.executeUpdate(SqlExecutor.java:80)
    at com.ibatis.sqlmap.engine.mapping.statement.MappedStatement.sqlExecuteUpdate(MappedStatement.java:216)
    at com.ibatis.sqlmap.engine.mapping.statement.MappedStatement.executeUpdate(MappedStatement.java:94)
    ... 5 more
false

错误的意思是：重复输入“1”键为“主” 进入数据库中，查询表tbl_student的时候，发现三条记录，其中一条主键为1。考虑到我进行测试的时候，数据库中默认主键是为1 。所以将数据库中主键为1的这条记录删除。然后测试就通过了。

总结：ibatis中主键被我设置成了默认的1.导致进行测试的时候直接从默认的1开始。然后报错了、将主键默认值设置为null就解决了问题。