try {
conn.setAutoCommit(false);
PreparedStatement state=conn.prepareStatement
("insert into mytab(name,age,salary) values ( , , )");
for(int i=0;i<3000;i++){
state.setString(1,"yiha_"+i );
state.setInt(2, 22);
state.setInt(3, 3000+i);
state.addBatch();
}
state.executeBatch();
conn.commit();
state.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
######################数据库连接connection######################
private static String url="jdbc:mysql://" +
"localhost:3306/mydb useUnicode=true&characterEncoding=UTF-8";
private static String driver="com.mysql.jdbc.Driver";
private static String name="root";
private static String pwd="root";
public static Connection getConnection(){
Connection conn;
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url, name, pwd);
return conn;
###################################################################
##现在数据库中有3003条数据，我们看一下检索数据时间。
#如检索：
id NAME age salary
| 2894 | yiha_2890 | 22 | 5890 |
#id以及name为索引，但是age和salary为非索引
mysql> select * from mytab where id=2894;
+------+-----------+-----+--------+
| id | name | age | salary |
+------+-----------+-----+--------+
| 2894 | yiha_2890 | 22 | 5890 |
+------+-----------+-----+--------+
1 row in set (0.00 sec)
mysql> select * from mytab where salary=5890;
+------+-----------+-----+--------+
| id | name | age | salary |
+------+-----------+-----+--------+
| 2894 | yiha_2890 | 22 | 5890 |
+------+-----------+-----+--------+
1 row in set (0.00 sec)
#可以看出无差别，也许数据仍旧太少，现在将数据提升到30000；
mysql> select * from mytab where id=30000; #id为索引
+-------+------------+-----+--------+
| id | name | age | salary |
+-------+------------+-----+--------+
| 30000 | yiha_29996 | 23 | 32996 |
+-------+------------+-----+--------+
1 row in set (0.00 sec)
mysql> select * from mytab where salary=32996;#salary为非索引
+-------+------------+-----+--------+
| id | name | age | salary |
+-------+------------+-----+--------+
| 30000 | yiha_29996 | 23 | 32996 |
+-------+------------+-----+--------+
1 row in set (0.02 sec)
#由于name也是索引，所以这里试一下用name查找数据：
mysql> select * from mytab where name='yiha_29996';#name为索引
+-------+------------+-----+--------+
| id | name | age | salary |
+-------+------------+-----+--------+
| 30000 | yiha_29996 | 23 | 32996 |
+-------+------------+-----+--------+
1 row in set (0.00 sec)
##虽然在数据多次实验中能够看出索引的作用，但是并不是很明显。以上每一组所耗费时间都是
#个人寻找的出现次数最多的时间。
##个人感觉测试索引效果挺无聊的，索引的作用很多文章都只写了可以精确查找，至于索引如何
#运用貌似很少有相关的东西。数据库中的数据还可以随意扩大，个人感觉先这样吧。