这里我不能进入while（rs.next（））{.....}语句。我试着准备简单的陈述，你看，并尝试打印而不是用println word＆＃34; data＆＃34;检查我是否在while语句中，但没有打印出来：（
Connection conn = null;
PreparedStatement prepStmt = null;
ResultSet rs = null;
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance();
String connectionUrl = "jdbc:sqlserver://FIO\\SQLEXPRESS;" +
"databaseName=Feedback;integratedSecurity=true";
conn = DriverManager.getConnection(connectionUrl);
//String sqlStmt = "SELECT SubjectName, Semester, Year, TrainerFirstName, TrainerLastName, StudentFirstName,StudentLastName, Answer FROM Feedback.dbo.quest WHERE TrainerFirstName='?' AND TrainerLastName='?' AND Semester=? AND Year=?";
String sqlStmt = "SELECT * FROM Feedback.dbo."+quest;
System.out.println("SQL Statement:\n\t" + sqlStmt);
prepStmt = conn.prepareStatement(sqlStmt);
//prepStmt.setString(1,ffname);
//prepStmt.setString(2, llname);
//prepStmt.setString(3, sem);
//prepStmt.setString(4,yea);
rs = prepStmt.executeQuery(sqlStmt);
while (rs.next()) {
System.out.println(rs.getString(1));
System.out.println("data:"+rs.getString(1) + rs.getInt(2)+rs.getInt(3)+rs.getString(4)+rs.getString(5)+rs.getString(6)+rs.getString(7)+rs.getString(8));
/*String id = rs.getString("id");
String firstName = rs.getString("first_name");
String lastName = rs.getString("last_name");
System.out.println("ID: " + id + ", First Name: " + firstName + ", Last Name: " + lastName);*/
}
} catch (ClassNotFoundException | IllegalAccessException | InstantiationException | SQLException e) {
}
它只打印了这个：
SQL语句： SELECT * FROM Feedback.dbo.Question1 绑定变量设置之前的准备语句： SQLServerPreparedStatement：1 绑定变量设置后的Prepared语句： SQLServerPreparedStatement：1 建立成功（总时间：20秒）
看来，while语句被省略了。
非常感谢你。
答案 0 :(得分：0)
准备语句必须链接到变量，然后执行。
如果您没有要绑定的变量，请使用Statement，然后使用executeQuery，而不是PrepareStatement。
下面显示Statement和PrepareStatement使用的示例代码。
import java.sql.*;
public class TestSql {
public static void main(String[] args) {
Connection con = null;
PreparedStatement ps = null;
Statement s = null;
ResultSet rs = null;
try {
try {
System.out.println("Buscando el driver JDBC...");
Class.forName("com.mysql.jdbc.Driver"
// "org.postgresql.Driver"
// "oracle.jdbc.driver.OracleDriver"
// "com.microsoft.sqlserver.jdbc.SQLServerDriver"
// "org.firebirdsql.jdbc.FBDriver"
).newInstance();
System.out.println("...Encontró el driver JDBC");
} catch (Exception e) {
System.out.println("No pudo encontrar el driver JDBC !!!!");
e.printStackTrace(System.out);
return;
}
try {
System.out.println("Connectando a la base de datos...");
con = DriverManager
.getConnection("jdbc:mysql://localhost/curso?user=curso&password=123"
// "jdbc:postgresql://localhost/curso:5432","postgres","123"
// "jdbc:oracle:thin:@192.168.0.10:1521/XE","curso","123"
// "jdbc:sqlserver://192.168.0.100:1433/database=curso/user=curso/password=123"
// "jdbc:firebirdsql:127.0.0.1:C:/firebird/data/curso.gdb","curso","123"
);
System.out.println("...Connectado a la base de datos");
} catch (Exception e) {
System.out
.println("No pudo conectarse a la base de datos !!!!");
e.printStackTrace(System.out);
return;
}
try {
System.out
.println("Lista de empleados con salario inferior a $30,000");
s = con.createStatement();
rs = s
.executeQuery("select concat(first_name,' ',last_name) as full_name from employee where salary < 30000");
// "select first_name||' '||last_name as full_name from employee where salary < 30000");
while (rs.next()) {
System.out.println(rs.getString("full_name"));
}
} catch (java.sql.SQLException e) {
System.out.println("Unable to step thru results of query");
showSQLException(e);
return;
}
try {
System.out
.println("===============================================");
System.out
.println("Lista de empleados con salario entre $30,000 y $40,000");
ps = con
.prepareStatement("select concat(first_name,' ',last_name) as full_name from employee where salary between ? and ?");
// "select first_name||' '||last_name as full_name from employee where salary between ? and ?");
ps.setInt(1, 30000);
ps.setInt(2, 40000);
rs = ps.executeQuery();
while (rs.next()) {
System.out.println(rs.getString("full_name"));
}
} catch (java.sql.SQLException e) {
System.out.println("Unable to submit a static SQL query.");
showSQLException(e);
return;
}
} finally {
System.out.println("Cerrando la conexion a la base de datos.");
try {
if (rs != null) {
rs.close();
}
} catch (java.sql.SQLException e) {
showSQLException(e);
}
try {
if (ps != null) {
ps.close();
}
} catch (java.sql.SQLException e) {
showSQLException(e);
}
try {
if (con != null) {
con.close();
}
} catch (java.sql.SQLException e) {
showSQLException(e);
}
System.out.println("Fin");
}
}
private static void showSQLException(java.sql.SQLException e) {
java.sql.SQLException next = e;
while (next != null) {
System.out.println(next.getMessage());
System.out.println("Error Code: " + next.getErrorCode());
System.out.println("SQL State: " + next.getSQLState());
next = next.getNextException();
}
}
}