java 字符串与 mysql 字符串

Question

mysql> CREATE database testing CHARACTER SET utf16;
Query OK, 1 row affected (0.00 sec)

mysql> USE testing;
Database changed

mysql> CREATE TABLE t (str varchar(64));
Query OK, 0 rows affected (0.43 sec)

mysql> INSET INTO t values ("1234567891234567");
Query OK, 1 row affected (0.00 sec)

=============================

然后我有一段java代码

Connection connection = DriverManager.getConnection(url, usr, pass);
Statement statement = connection.createStatement();

statement.execute("USE  testing");

ResultSet rst = statement.executeQuery("SELECT str, LENGTH(str) FROM t;");
while (rst.next())
             System.out.print("java length: " + rst.getString(1).length() 
                     + "\nmysql length: " + rst.getInt(2));

这会给

java length: 16
mysql length: 32

我不明白为什么长度不同。我明确地将数据库的字符集设置为 UTF16(这是 Java 的默认字符集，对吧？)为什么我仍然得到不一致的长度值？

Answer 1

mySql 函数“CHAR_LENGTH()”返回#/Unicode 字符(如 Java 的“.length”)。

MySQL 函数“LENGTH()”返回#/bytes。

这是 MySQL 引用:

• > http://dev.mysql.com/doc/refman/5.5/en/string-functions.html