做项目时犯的弱智错误

弱智问题一:

在往MySql的表中插数据时,老是报SQL Error: 1064, SQLState: 42000错误,郁闷了好半天,上网搜了才发现,是因为表中字段的名字用了MySql的关键字,晕倒,以后一定要注意。

MySQL的保留字有以下这些,使用中需要注意。(从网上打劫过来的)

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 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 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
LEADING LEAVE LEFT
LIKE LIMIT LINEAR
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 RAID0 RANGE
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
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 USAGE USE
USING UTC_DATE UTC_TIME
UTC_TIMESTAMP VALUES VARBINARY
VARCHAR VARCHARACTER VARYING
WHEN WHERE WHILE
WITH WRITE X509
XOR YEAR_MONTH ZEROFILL

 

弱智问题二:

需要同事帮忙调整程序,但是同事却死人的连不上我机器上的MySql,继续郁闷,继续网上搜索。

发现一个补救办法是:让mysql库中user表的host字段为“%”,以接受远程控制,这样别人就可以用mysql -h ***.***.***.***(你的IP) -u root -p密码 进行连接并操作数据库了。
还有一个是在安装时需要注意的:在设置用户的时候会有一个复选框,问是否让别人连接,这里需要选中!

弱智问题三:

用Hibernate,设置PO映射文件的主键字段的属性为“natively”(),但是往表里面查数据时老是说“The database returned no natively generated identity value”。

最后确认是在表的属性中没有设置主键为“auto increment”,这个可以用数据库连接工具在表属性中设置,也可以在建表的时候,在主键字段后面标注上:CREATE TABLE `log` (`LOGID` int(11) NOT NULL auto_increment, PRIMARY KEY  (`LOGID`)) ENGINE=InnoDB DEFAULT CHARSET=gbk

弱智问题四:

做报表的时候,需要查出内容为Null的记录,在查询条件里面写了“XX=null”,结果怎么也查不出来,郁闷半天,后来试了下“XX is null”,就查出来了,哎,俺真是够白痴的了!

 

转载于:https://www.cnblogs.com/jinqiuqiu1120/archive/2008/09/24/1296144.html

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