JDBC Resultset 結果集范例
jdbc resultset 結果集范例
jdbc resultset 通過移動光標的方法瀏覽結果集。
1. resultset 移動光標的方法
| 編號 | 方法 | 描述 |
|---|---|---|
| 1 | public void beforefirst() throws sqlexception | 將光標移動到第一行之前 |
| 2 | public void afterlast() throws sqlexception | 將光標移動到最后一行之后。 |
| 3 | public boolean first() throws sqlexception | 將光標移動到第一行。 |
| 4 | public void last() throws sqlexception | 將光標移動到最后一行。 |
| 5 | public boolean absolute(int row) throws sqlexception | 將光標移動到指定的行。 |
| 6 | public boolean relative(int row) throws sqlexception | 從當前指向的位置，將光標向前或向后移動給定行數。 |
| 7 | public boolean previous() throws sqlexception | 將光標移動到上一行。 如果上一行關閉結果集，此方法返回false。 |
| 8 | public boolean next() throws sqlexception | 將光標移動到下一行。 如果結果集中沒有更多行，則此方法返回false。 |
| 9 | public int getrow() throws sqlexception | 返回光標指向的行號。 |
| 10 | public void movetoinsertrow() throws sqlexception | 將光標移動到結果集中的特殊行，該行可用于將新行插入數據庫。當前光標位置被記住。 |
| 11 | public void movetocurrentrow() throws sqlexception | 如果光標當前位于插入行，則將光標移回當前行; 否則，此方法什么也不做 |
2. resultset 瀏覽結果集范例
//step 1. import required packages
import java.sql.*;
public class navigatingresultset {
// jdbc driver name and database url
static final string jdbc_driver = "com.mysql.jdbc.driver";
static final string db_url = "jdbc:mysql://localhost/emp";
// database credentials
static final string user = "root";
static final string pass = "123456";
public static void main(string[] args) {
connection conn = null;
statement stmt = null;
try{
//step 2: register jdbc driver
class.forname("com.mysql.jdbc.driver");
//step 3: open a connection
system.out.println("connecting to database...");
conn = drivermanager.getconnection(db_url,user,pass);
//step 4: execute a query to create statment with
// required arguments for rs example.
system.out.println("creating statement...");
stmt = conn.createstatement(
resultset.type_scroll_insensitive,
resultset.concur_read_only);
string sql;
sql = "select id, first, last, age from employees";
resultset rs = stmt.executequery(sql);
// move cursor to the last row.
system.out.println("moving cursor to the last...");
rs.last();
//step 5: extract data from result set
system.out.println("displaying record...");
//retrieve by column name
int id = rs.getint("id");
int age = rs.getint("age");
string first = rs.getstring("first");
string last = rs.getstring("last");
//display values
system.out.print("id: " + id);
system.out.print(", age: " + age);
system.out.print(", first: " + first);
system.out.println(", last: " + last);
// move cursor to the first row.
system.out.println("moving cursor to the first row...");
rs.first();
//step 6: extract data from result set
system.out.println("displaying record...");
//retrieve by column name
id = rs.getint("id");
age = rs.getint("age");
first = rs.getstring("first");
last = rs.getstring("last");
//display values
system.out.print("id: " + id);
system.out.print(", age: " + age);
system.out.print(", first: " + first);
system.out.println(", last: " + last);
// move cursor to the first row.
system.out.println("moving cursor to the next row...");
rs.next();
//step 7: extract data from result set
system.out.println("displaying record...");
id = rs.getint("id");
age = rs.getint("age");
first = rs.getstring("first");
last = rs.getstring("last");
//display values
system.out.print("id: " + id);
system.out.print(", age: " + age);
system.out.print(", first: " + first);
system.out.println(", last: " + last);
//step 8: clean-up environment
rs.close();
stmt.close();
conn.close();
}catch(sqlexception se){
//handle errors for jdbc
se.printstacktrace();
}catch(exception e){
//handle errors for class.forname
e.printstacktrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
stmt.close();
}catch(sqlexception se2){
}// nothing we can do
try{
if(conn!=null)
conn.close();
}catch(sqlexception se){
se.printstacktrace();
}//end finally try
}//end try
system.out.println("goodbye!");
}//end main
}//end jdbcexample
3. 編譯運行
f:\worksp\jdbc>javac -djava.ext.dirs=f:\worksp\jdbc\libs navigatingresultset.java f:\worksp\jdbc>java -djava.ext.dirs=f:\worksp\jdbc\libs navigatingresultset
運行上面代碼，得到以下結果：
Java實戰