java jdbc in查询,Java中的SQL查询：（JDBC）如何使用SELECT语句？

This is my query to connect to my database.

SELECT naam, kleur, sector, aantalZilverstukken, Spel_naam

FROM speler

WHERE Spel_Naam = ?

I work in the console of netbeans. When I want to show the records of table Speler with the Spel_Naam.

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.

Like WHERE Spel_Naam = ?

The question mark need to be the name that I typed in

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 geefSpelers()

{

List spelerLijst = new ArrayList();

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;

}

解决方案

Use PreparedStatements:

String LEES_SPELERS_SQL = "SELECT ... WHERE Spel_Naam = ?";

PreparedStatement prepStmt = con.prepareStatement(LEES_SPELERS_SQL);

prepStmt.setString(1, naam);

ResultSet rs = prepStmt.executeQuery();

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.