记录下遇到的一个关于使用sql更新数据报错的bug。
一个修改书籍信息的功能，在前端正常执行了，响应码为200。但是后台报错了

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'usage='教育类',isbn='1132135545'  WHERE  bookId=6' at line 1
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:408)
	at com.mysql.jdbc.Util.getInstance(Util.java:383)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1062)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4208)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4140)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2597)
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2758)
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2826)
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2082)
	at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2334)
	at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2262)
	at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2246)
	at com.hbue.dao.impl.BookDaoImpl.update(BookDaoImpl.java:125)
	at com.hbue.service.impl.BookServiceImpl.updateBook(BookServiceImpl.java:32)
	at com.hbue.controller.BookController.updateBook(BookController.java:111)
	at com.hbue.controller.BookController.doGet(BookController.java:43)
	at com.hbue.controller.BookController.doPost(BookController.java:166)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

UPDATE  book  SET  bookName=?,author=?,publisher=?,publishdate=?,price=?,usage=?,isbn=?  WHERE  bookId=?

在检查完sql语句后，并没有问题。最后发现是因为数据库有一个字段usage是mysql的关键字，将数据库的该属性和sql语句的属性修改后修改后执行,才能执行成功。
以后在数据库里建表的时候,应该注意下不要用到了sql里的关键字作为字段名,不然有可能报错了。