hbm2ddl.auto设置为update时不能工作排查方法!

问题描述：

在调试hibernate的时候发现设置hbm2ddl.auto设置为update是不能工作，eclipse中报如下错误：

Hibernate: insert into news (title, content) values (?, ?)

Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not insert: [com.ericsson.ewanbao.News]

at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:92)

at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)

...................

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'hibernate.news' doesn't exist

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

...............

问题分析：

经检查数据库发现，news表确实创建不成功，可见hbm2ddl.auto设置为update没有能够建立表

解决步骤：

1.把mysql的general-log打开，这样可以跟踪所有的sql语句；

2.再次执行程序，在general-log的最后发现如下sql语句：

3 Query
SHOW FULL TABLES FROM `hibernate` LIKE 'news'

3 Query
create table news (id integer not null auto_increment, title varchar(255), content varchar(255), primary key (id)) type=InnoDB

3 Query
SHOW FULL TABLES FROM `hibernate` LIKE 'PROBABLYNOT'

3 Query
SET autocommit=0

3 Query
SET autocommit=1

3 Query
SET autocommit=0

3 Query
insert into news (title, content) values ('???????', '???????????!')

3 Query
SHOW FULL TABLES FROM `hibernate` LIKE 'PROBABLYNOT'

3.可以发现hibernate已经发送了见表语句给数据库，为什么建表没有成功了？尝试拷贝这些建表语句到sql控制台执行，得到如下结果：

mysql> create table news (id integer not null auto_increment, title varchar(255), content varchar(255), primary key (id)

) type=InnoDB;

ERROR 1064 (42000): 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 'type=InnoDB' at line 1

4.可以看到是sql语句错误，经分析发现是hibernate.dialect的设置错误，原先设置为org.hibernate.dialect.MySQLInnoDBDialect，应该修改为org.hibernate.dialect.MySQL5InnoDBDialect