Jdbc查询某个表字段集合

虾米链接：http://2814704901.iteye.com/blog/1936512

查询某个表字段分两种： 连表查询和单个查询

一、连表查询

//根据DutyId查询用户Email

public String getEmail(int dutyId){

Connection con = ConnectionGet.getConnection();

Statement st = null;

ResultSet rs = null;

String Email="";

try {

Class.forName("oracle.jdbc.driver.OracleDriver");

String sql="select u.user_emil from tb_yqcj_duty t,tb_user u where t.user_id=u.user_id and t.duty_id="+dutyId;

st = con.createStatement();

rs = st.executeQuery(sql);

while(rs.next()){

Email=rs.getString(1);//jdbc中的字段索引从1开始 Hibernate是从0开始的

}

} catch (Exception e) {

e.printStackTrace();

}finally{

this.closeCon(st, rs, con);

}

return Email;

}

二、单表查询  既可以像连表那样也可以使用自己的字段

//链接数据库查询预警任务的Id

public Map<String,String> getWarnDutyId(){

Map<String,String> map=new HashMap<String,String>();

Connection con = ConnectionGet.getConnection();

Statement st = null;

ResultSet rs = null;

try {

Class.forName("oracle.jdbc.driver.OracleDriver");

String sql="select * from tb_yqcj_duty t where t.is_warning=0";

st = con.createStatement();

rs = st.executeQuery(sql);

while (rs.next()) {

map.put(rs.getString("duty_id"), rs.getString("keyword"));//根据表字段名称查询

}

} catch (Exception e) {

e.printStackTrace();

}finally{

this.closeCon(st, rs, con);

}

return map;

}

//关闭链接

public void closeCon(Statement st,ResultSet rs,Connection con){

try {

if(rs!=null){

rs.close();

}

if(st!=null){

st.close();

}

if(con!=null){

con.close();

}

} catch (Exception e) {

e.printStackTrace();

}

}