如何使用JDBC在数据库中插入引用值？

Question

我试图使用下面的代码将值插入Oracle 10g数据库，但在执行时出现了“缺失表达式”的错误。我必须将引用值传递到insert子句中，但不知道确切的语法或方法。请帮我渡过难关。谢谢。

学生表：-

                      Sid       VARCHAR2(200) PRIMARY KEY  CHECK(Sid>0),
                      Pass_word VARCHAR2(10) NOT NULL,
                      S_name    VARCHAR2(20) NOT NULL,
                      G_name    VARCHAR2(20)         ,
                      Branch    VARCHAR2(10) NOT NULL,
                      D_company VARCHAR2(20)         ,
                      B_Percent INT NOT NULL CHECK(B_Percent<100),
                      twelth_percent INT NOT NULL CHECK(twelth_percent<100),
                      tenth_percent INT NOT NULL  CHECK(tenth_percent<100),
                      Certify   VARCHAR2(30),
                      Semester  INT NOT NULL CHECK(Semester<9),
                      D_Birth   DATE NOT NULL,
                      Sex       VARCHAR2(6) NOT NULL

代码：

Connection connection = null;

try
{

  // Load the JDBC driver

   String driverName = "sun.jdbc.odbc.JdbcOdbcDriver";

   Class.forName(driverName);

    connection = DriverManager.getConnection("jdbc:odbc:placement","siddharth","sid");

    studentID = StudentID.getText();
    spassword = PasswordField.getPassword();
    studentname = NameField.getText();
    Gname = GuardianField.getText();
    branch = BranchField.getText();
    dcompany = DcompanyField.getText();
    bpercent = BtechField1.getText();
    twelthpercent = TwelthField.getText();
    tenthpercent = TenthField.getText();
    semester = SemesterField.getText();
    certify = CertificationField.getText();
    sex = SexCombo.getActionCommand();
    date =  (Date) DateTextField1.getValue();



    Statement stmt = connection.createStatement();
    stmt.executeUpdate("insert into student " +"(sid,pass_word,s_name,g_name,branch,d_company,b_percent,twelth_percent,tenth_percent,certify,semester,d_birth,sex)"+
                 "values(studentID, spassword,studentname,Gname,branch,dcompany,bpercent,twelthpercent,tenthpercent,certify,semester,date,sex)" );

    stmt.close();
    connection.close();
    }

    catch (ClassNotFoundException e) {
    // Could not find the database driver
      JOptionPane.showMessageDialog(null,e);
    } 
    catch (SQLException e) {
    // Could not connect to the database
      JOptionPane.showMessageDialog(null,e);
     } 

Answer 1

当前，SQL语句如下所示：

insert into student (sid, pass_word, ...) values (studentID, spassword, ...)

变量名对SQL本身没有任何意义。

你应该用一份准备好的声明。例如，您的SQL应该如下所示：

insert into student (sid, pass_word, ...) values (?, ?, ...)

然后你用：

PreparedStatement stmt = connection.prepareStatement(sql);
stmt.setString(1, studentID);
stmt.setString(2, spassword);

// etc

有关更多信息，请参见关于准备语句的JDBC教程。

Answer 2

为了安全起见，你应该使用预先准备好的语句。

准备查询字符串

String updateString = "update " + dbName + ".COFFEES " +
                      "set SALES = ? where COF_NAME = ?";

使用此查询创建一个PrepartedStatement：

updateSales = connnection.prepareStatement(updateString);

填好吗？有你价值的空间持有者：

updateSales.setInt(1, myVariable1);
updateSales.setString(2, myVariable2);

执行查询

updateSales.executeUpdate();