Duplicate entry '1' for key 'XX_XXXXXXXXXXX'

意思很明白，就是id重复了

但是我们去查看数据库时发现根本就没有这个id，也就是说不会出现id重复

完整错误提示如下

SEVERE: Servlet.service() for servlet [javalab] in context with path [/javalab] threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 'UK_ql3vfgoa6qsrq6o9x8dfo7fcc'
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
	at com.mysql.jdbc.Util.getInstance(Util.java:386)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1041)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4190)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4122)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2570)
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731)
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2818)
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2157)
	at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2460)
	at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2377)
	at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2361)
	at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208)
	at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:96)
	at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:58)
	at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3032)
	at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3551)
	at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:98)
	at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:492)
	at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:197)
	at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:181)
	at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:216)

出现这个错误是因为您胡乱的操作了数据库，导致了数据表的损坏，所以将这个表备份吧，然后重新建立表即可解决