java - JDBC 连接代码错误
问题描述
我有一个需要 Java-Mysql 连接的项目。我一直在尝试从一个按钮连接两个表,以便在四个 JLabels 和一个 JTextArea 中给我一个输出。
它显示我的 SQL 语法有错误。
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
try {
Class.forName("java.sql.Driver");
Connection con = DriverManager.getConnection("jdbc:Mysql://localhost/nami", "root", "123456");
Statement st = con.createStatement();
String S =
"Select mobile,state,mobile,email,job from signup where email = " + "mil@gmail.com" + ";";
String P = "Select INFORMATION FROM pinfo where email = " + "mil@gmail.com" + ";";
ResultSet rs = st.executeQuery(S);
ResultSet rs2 = st.executeQuery(P);
while (rs.next()) {
String JOB = rs.getString("JOB");
String state = rs.getString("state");
String no = rs.getString("mobile");
String email = rs.getString("email");
jLabel5.setText(JOB);
jLabel16.setText(state);
jLabel31.setText(no);
jLabel7.setText(email);
}
while (rs2.next()) {
String info = rs.getString("information");
jTextArea1.setText(info);
}
con.close();
st.close();
rs.close();
rs2.close();
} catch (Exception e) {
JOptionPane.showMessageDialog(null, "Error" + e.getMessage());
}
}
解决方案
在WHERE
声明中,您必须通过用单引号括起来来引用实际值'
。这在 MySQL 文档章节
9.1.1 String Literals中有解释。您的代码应该是:
String P = "Select INFORMATION FROM pinfo where email = 'mil@gmail.com';";
如果您打算使用 JDBC,请了解准备好的语句。请参阅使用准备好的语句。