com.mysql.jdbc.MysqlDataTruncation: Data truncation: Data too long for column 'user_name' at row 1
错误，具体信息如下：
严重: Servlet.service() for servlet default threw exceptio
com.mysql.jdbc.MysqlDataTruncation: Data truncation: Data too long for column 'user_name' at row 1
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2868)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573)
at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1160)
at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:685)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1400)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1314)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1299)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeUpdate(NewProxyPreparedStatement.java:105)
at org.springframework.jdbc.core.JdbcTemplate$2.doInPreparedStatement(JdbcTemplate.java:745)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:538)
at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:739)
at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:797)
at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:805)
at com.bester.blog.dao.impl.UserDAOImpl.add(UserDAOImpl.java:25)
at com.bester.blog.service.impl.UserServiceImpl.add(UserServiceImpl.java:12)
at com.bester.blog.web.action.UserAction.add(UserAction.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
........................
看着这错误信息，怎么有似曾相识的感觉呢。但就是记不起来了。根据字面意思，一位是输入超出范围了。但我的user_name字段设置的是varchar(45),只输入了三个中文，怎么可能超出呢？
google一下，一看到字符设置字眼，忽然想起以前碰到过这个问题的。只是早以到了九霄云外罢了。
原因在于：建表的时候，表的编码和字段编码都是默认的latin1，设置为utf8后，问题解决。