MySQL基本数据类型与Java基本数据类型
早上写了篇博客,发现蛮有感觉的,工作了一整天,发现又有些东西可以写了,呵呵…… 分享下……
经过几天的Dao层和Service层代码的编写,今天终于到了看成果的时候了,把项目启动后,输入一个Url访问项目接口。糟糕,报错,没事,Dao层的错误,没问题,就是SQL的问题。说明下,我们公司操作数据库是用jdbc的,所有比较麻烦,但是效率相对来说是蛮高的。
但是,我仔细对比了代码,没发现问题了,但总是抱 “Statement parameter 13 not set.” 错误。
没办法,只能一步一步的找咯。我把Sql语句和各个参数都打印出来。然后放到SQLyog里去执行。没问题额。
我把tomcat在次启动,访问接口,还是抱 “Statement parameter 13 not set.” 错误。我在仔细看了下,不会是关键字的问题了吧?唉…… 试下呗,Pass 。哦,我焕然大雾,原来是类型不匹配,Java是short类型,mysql是tinyint类型。
下面是我从网上找来的Java基本数据类型和mysql基本数据类型对照表:
BIT(1) (new in MySQL-5.0) | BIT | java.lang.Boolean |
BIT( > 1) (new in MySQL-5.0) | BIT | byte[] |
TINYINT | TINYINT | java.lang.Boolean if the configuration property
tinyInt1isBit is set to
true (the default) and the storage size is 1, or
java.lang.Integer if not. |
BOOL, BOOLEAN | TINYINT | See TINYINT, above as these are aliases for TINYINT(1), currently. |
SMALLINT[(M)] [UNSIGNED] | SMALLINT [UNSIGNED] | java.lang.Integer (regardless if UNSIGNED or not) |
MEDIUMINT[(M)] [UNSIGNED] | MEDIUMINT [UNSIGNED] | java.lang.Integer, if UNSIGNED
java.lang.Long (C/J 3.1 and earlier), or
java.lang.Integer for C/J 5.0 and later |
INT,INTEGER[(M)] [UNSIGNED] | INTEGER [UNSIGNED] | java.lang.Integer , if UNSIGNED
java.lang.Long |
BIGINT[(M)] [UNSIGNED] | BIGINT [UNSIGNED] | java.lang.Long , if UNSIGNED
java.math.BigInteger |
FLOAT[(M,D)] | FLOAT | java.lang.Float |
DOUBLE[(M,B)] | DOUBLE | java.lang.Double |
DECIMAL[(M[,D])] | DECIMAL | java.math.BigDecimal |
DATE | DATE | java.sql.Date |
DATETIME | DATETIME | java.sql.Timestamp |
TIMESTAMP[(M)] | TIMESTAMP | java.sql.Timestamp |
TIME | TIME | java.sql.Time |
YEAR[(2|4)] | YEAR | If yearIsDateType configuration property is set to false, then the returned object type is
java.sql.Short . If set to true (the default) then an object of type
java.sql.Date (with the date set to January 1st, at midnight). |
CHAR(M) | CHAR | java.lang.String (unless the character set for the column is
BINARY, then byte[] is returned. |
VARCHAR(M) [BINARY] | VARCHAR | java.lang.String (unless the character set for the column is
BINARY, then byte[] is returned. |
BINARY(M) | BINARY | byte[] |
VARBINARY(M) | VARBINARY | byte[] |
TINYBLOB | TINYBLOB | byte[] |
TINYTEXT | VARCHAR | java.lang.String |
BLOB | BLOB | byte[] |
TEXT | VARCHAR | java.lang.String |
MEDIUMBLOB | MEDIUMBLOB | byte[] |
MEDIUMTEXT | VARCHAR | java.lang.String |
LONGBLOB | LONGBLOB | byte[] |
LONGTEXT | VARCHAR | java.lang.String |
ENUM('value1','value2',...) | CHAR | java.lang.String |
SET('value1','value2',...) | CHAR | java.lang.String |
松下问童子,言师采药去。
只言此山中,云深不知处。