今天利用Hibernate4.0上往MySQL 5数据库插入一个Entity时,一直出现以下的错误:
You have an error in your SQL syntax; check the manual thatcorresponds to your MySQL server version for the right syntax to user near `show, sid) value
一直觉得不应该啊,怎么会呢,不可能啊,自己就是在想这些无用的东西,也尝试了好多次,感觉都是徒劳,后来采取科学的解决步骤来逐步地一点一滴地循序渐进地找到解决方法,其实后来证明虽然一步一步来,看起来慢,但这毕竟是一条科学的方法,只要沿着这条道路往前走,离正确的答案只会越来越近的,肯定会迅速发现问题的所在的。这其中,我觉得排除法是一个很好的方法,例如我要插入这个Entity不成功,那我就把这个Entity的其他attribute先去掉,只保留一个attribute,然后看能否insert成功;然后逐步加入其它的attribute,直到一个attribute被加进去以后,引发了上述错误,这样我们就能够迅速地确定到底是哪一个attribute引发了上述错误,很快地找到问题的根源,有的放矢。
事实证明,开始漫无目的方法花费了一天时间都没能找到正确的解决方法,而按照后一种方法,很快就找到问题的原因(加入show这个attribute后开始出错)。下面针对此问题开始分析问题原因。
Hibernate 定义:
@Column(nullable = false)
private boolean show;
MySQL中定义是这样的:
Show bit(1) not null
一种可能是因为MySQL中的bit datatype和JAVA中的boolean不能正确转换,stackoverflow中有个类似的问题如下:
Causedby: org.hibernate.HibernateException:
Wrong column type in PUBLIC.PUBLIC.EVENT for column Checked. Found: bit,expected: boolean
I worked this out by adding columnDefinition = "BIT" to the@Column line.
@Column(name = "B", columnDefinition = "BIT", length =1)
public boolean isB() {
return b;
}
Its defined as a'BIT(1)' in the DB as well. Also worked with TINYINT. This is the easiestsolution I've found since the change is super-minor and no need to touch theDB.
Using: MySQL Server5.5.13, Hibernate 4.1.1, JDK 1.6
我按照以上的思路,改造了我的show属性,可是还是不成功,由此可见,我的问题只是与上面这个问题相似,但不是由以上原因引起的。还有一些人建议should not use BIT columns in MySQL,建议使用tinyint,但也不是问题的主要原因。
应该是show属性引起的,继续google,还是stackoverflow中有人碰到类似的问题,解决方法如下:
Ithink the problem is that ORDER is aMySQL reserved word.
To get the INSERTstatement to execute, you'd need to have that column name enclosed inbackticks, like this:
insert into folder (folder_name, `order`) values (?,?)
OKI've found solution; we still can use 'order'keyword as column name like this:
@Column(name = "`order`", length = 10,precision =0)
private int order;
好吧,既然order是MySQL的reserved word,那show也很有可能,果然改成其他名称后立即得到解决:
@Column(name = "label_show", nullable = false)
private boolean show;
查阅MySQL 官方文档,可以得到Reserved Words in MySQL:
Table 2.1. Reserved Words in MySQL 5.0
ADD |
ALL |
ALTER |
ANALYZE |
AND |
AS |
ASC |
ASENSITIVE |
BEFORE |
BETWEEN |
BIGINT |
BINARY |
BLOB |
BOTH |
BY |
CALL |
CASCADE |
CASE |
CHANGE |
CHAR |
CHARACTER |
CHECK |
COLLATE |
COLUMN |
CONDITION |
CONNECTION[a] |
CONSTRAINT |
CONTINUE |
CONVERT |
CREATE |
CROSS |
CURRENT_DATE |
CURRENT_TIME |
CURRENT_TIMESTAMP |
CURRENT_USER |
CURSOR |
DATABASE |
DATABASES |
DAY_HOUR |
DAY_MICROSECOND |
DAY_MINUTE |
DAY_SECOND |
DEC |
DECIMAL |
DECLARE |
DEFAULT |
DELAYED |
DELETE |
DESC |
DESCRIBE |
DETERMINISTIC |
DISTINCT |
DISTINCTROW |
DIV |
DOUBLE |
DROP |
DUAL |
EACH |
ELSE |
ELSEIF |
ENCLOSED |
ESCAPED |
EXISTS |
EXIT |
EXPLAIN |
FALSE |
FETCH |
FLOAT |
FLOAT4 |
FLOAT8 |
FOR |
FORCE |
FOREIGN |
FROM |
FULLTEXT |
GOTO[b] |
GRANT |
GROUP |
HAVING |
HIGH_PRIORITY |
HOUR_MICROSECOND |
HOUR_MINUTE |
HOUR_SECOND |
IF |
IGNORE |
IN |
INDEX |
INFILE |
INNER |
INOUT |
INSENSITIVE |
INSERT |
INT |
INT1 |
INT2 |
INT3 |
INT4 |
INT8 |
INTEGER |
INTERVAL |
INTO |
IS |
ITERATE |
JOIN |
KEY |
KEYS |
KILL |
LABEL[c] |
LEADING |
LEAVE |
LEFT |
LIKE |
LIMIT |
LINES |
LOAD |
LOCALTIME |
LOCALTIMESTAMP |
LOCK |
LONG |
LONGBLOB |
LONGTEXT |
LOOP |
LOW_PRIORITY |
MATCH |
MEDIUMBLOB |
MEDIUMINT |
MEDIUMTEXT |
MIDDLEINT |
MINUTE_MICROSECOND |
MINUTE_SECOND |
MOD |
MODIFIES |
NATURAL |
NOT |
NO_WRITE_TO_BINLOG |
NULL |
NUMERIC |
ON |
OPTIMIZE |
OPTION |
OPTIONALLY |
OR |
ORDER |
OUT |
OUTER |
OUTFILE |
PRECISION |
PRIMARY |
PROCEDURE |
PURGE |
READ |
READS |
REAL |
REFERENCES |
REGEXP |
RELEASE |
RENAME |
REPEAT |
REPLACE |
REQUIRE |
RESTRICT |
RETURN |
REVOKE |
RIGHT |
RLIKE |
SCHEMA |
SCHEMAS |
SECOND_MICROSECOND |
SELECT |
SENSITIVE |
SEPARATOR |
SET |
SHOW |
SMALLINT |
SONAME |
SPATIAL |
SPECIFIC |
SQL |
SQLEXCEPTION |
SQLSTATE |
SQLWARNING |
SQL_BIG_RESULT |
SQL_CALC_FOUND_ROWS |
SQL_SMALL_RESULT |
SSL |
STARTING |
STRAIGHT_JOIN |
TABLE |
TERMINATED |
THEN |
TINYBLOB |
TINYINT |
TINYTEXT |
TO |
TRAILING |
TRIGGER |
TRUE |
UNDO |
UNION |
UNIQUE |
UNLOCK |
UNSIGNED |
UPDATE |
UPGRADE[d] |
USAGE |
USE |
USING |
UTC_DATE |
UTC_TIME |
UTC_TIMESTAMP |
VALUES |
VARBINARY |
VARCHAR |
VARCHARACTER |
VARYING |
WHEN |
WHERE |
WHILE |
WITH |
WRITE |
XOR |
YEAR_MONTH |
ZEROFILL |
|
|
来自 <http://dev.mysql.com/doc/mysqld-version-reference/en/mysqld-version-reference-reservedwords-5-0.html>