Java中的SQL查询:(JDBC)如何使用SELECT语句? [英] SQL queries in Java: (JDBC) How to use the SELECT statement?
问题描述
这是我要连接到数据库的查询.
This is my query to connect to my database.
SELECT naam, kleur, sector, aantalZilverstukken, Spel_naam
FROM speler
WHERE Spel_Naam = ?
我在netbeans控制台中工作.当我想用Spel_Naam显示表Speler的记录时.
I work in the console of netbeans. When I want to show the records of table Speler with the Spel_Naam.
在控制台中,我想键入表Spel的主键,然后向我显示控制台中表Speler的记录.我怎样才能做到这一点.
In the console I want to type a primary key of the table Spel and then it shows me the records of the table Speler in the console. How can I do this.
像WHERE Spel_Naam = ?
问号必须是我输入的名称
The question mark need to be the name that I typed in
select语句正确吗?我想在控制台中键入Spel_Naam,然后它必须连接到数据库并向我提供表Speler的记录.我该怎么办?
Is the select statement correct? I want to type the Spel_Naam in the console and then It must connect to the database and give me the records of table Speler. How can I do this?
public class SpelerMapper
{
private final static String LEES_SPELERS_SQL = "SELECT naam, kleur, sector, aantalZilverstukken, Spel_naam FROM speler WHERE Spel_Naam = ?";
public List<Speler> geefSpelers()
{
List<Speler> spelerLijst = new ArrayList<Speler>();
Statement statement;
Connection connection = PersistentieController.getInstance().getConnection();
try
{
statement = connection.createStatement();
// query database
ResultSet resultSet = statement.executeQuery(LEES_SPELERS_SQL);
while (resultSet.next())
{
String naam = resultSet.getString("naam");
String kleur = resultSet.getString("kleur");
int sector = resultSet.getInt("sector");
int aantalZilverstukken = resultSet.getInt("aantalZilverstukken");
Speler speler = new Speler(naam ,kleur, sector , aantalZilverstukken);
spelerLijst.add(speler);
}
statement.close();
return spelerLijst;
} catch (SQLException e)
{
e.printStackTrace();
}
return null;
}
推荐答案
使用PreparedStatement
s:
String LEES_SPELERS_SQL = "SELECT ... WHERE Spel_Naam = ?";
PreparedStatement prepStmt = con.prepareStatement(LEES_SPELERS_SQL);
prepStmt.setString(1, naam);
ResultSet rs = prepStmt.executeQuery();
附加说明:作为另一种选择,SQL查询的连接是完成同一任务的不安全方法.有关更多信息,请参见此文章.
Additional note: while being another option, concatenation of the SQL query is an unsafe way of doing the same task. Refer to this article for more info.
这篇关于Java中的SQL查询:(JDBC)如何使用SELECT语句?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!