如何使用 PrepareStatement 在 Java 中执行 INSERT SELECT INTO

Question

我正在尝试通过从 2 个表中选择列中的特定数据来执行插入到 1 个表中的 INSERT INTO SELECT。问题是，它也将涉及来自 JTextField 的用户输入。我已经搜索了许多解决方案，但仍然出现错误，我只是不知道还能做什么。我使用 Java 作为 PL 和 Oracle 作为 DB。这是我到目前为止所得到的：

Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","ghost","slayer");

stmt = con.createStatement();

String sbjC = sbjCode.getText(); //textfield for subjectCode
String sbjN = sbjName.getText(); //textfield for subjectName
String matricsno = textstudentid.getText(); //textfield for matrics number
String sbjG = sbjGrade.getText(); //textfield for subjectGrade (not gonna be use in db, just for comparison)

String sql1 = "INSERT INTO transferred (subjectCode,subjectName,credit,prequisite,matricsNo) "
    + "SELECT b.subjectCode,b.subjectName,b.credit,b.prequisite,s.matricsNo "
    + "FROM bitm b, student s "
    + "WHERE b.subjectCode = '"+sbjC+"' AND b.subjectName = '"+sbjN+"' AND s.matricsNo = '"+matricsno+"'";

/* table Transferred has 5 column which are subjectCode,subjectName,credit,prequisite,matricsNo [matricsno as FK]
 * table bitm has 5 column [subjectCode as PK]
 * table student has 6 column [matricsno as PK]
 */

ps = con.prepareStatement(sql1);

ps.setString(1, sbjC);
ps.setString(2, sbjN);
ps.setString(3, "SELECT credit FROM bitm WHERE subjectCode = '"+sbjC+"' AND subjectName = '"+sbjN+"'");
ps.setString(4, "SELECT prequisite FROM bitm WHERE subjectCode = '"+sbjC+"' AND subjectName = '"+sbjN+"'");
ps.setString(5, "SELECT matricsno FROM student WHERE matricsno = '"+matricsno+"'");

ps.executeUpdate(sql1);

执行并将所需的所有数据插入 JTextField 后，我遇到的唯一错误是 java.sql.SQLException : Invalid column index。

SQL 语句已在 SQL Developer 中测试并成功。只是我对如何在 Java 上做到这一点有点困惑。 感谢您的所有回复和时间。 我是 Java 新手。

Answer 1

对于 PreparedStatement，您会编写代码吗？进入 sql 并稍后将其替换为值。

String sql1 = "INSERT INTO transferred (subjectCode,subjectName,credit,prequisite,matricsNo) "
                    + "SELECT b.subjectCode,b.subjectName,b.credit,b.prequisite,s.matricsNo "
                    + "FROM bitm b, student s "
                    + "WHERE b.subjectCode = ?  AND b.subjectName = ? AND s.matricsNo = ? ";


            ps = con.prepareStatement(sql1);

            ps.setString(1, sbjC);
            ps.setString(2, sbjN);
            ps.setString(3,matricsno);

ps.executeUpdate ();

应该这样做。

您的错误来自于提供参数（setString...）而不匹配？

Answer 2

很遗憾，您完全误解了preparedStatemet 的作用。 你要写吗？ -s 进入查询，preparedStatement 将以键入的方式替换它：

 String sql1 = "INSERT INTO transferred (subjectCode,subjectName,credit,prequisite,matricsNo) "
                    + "SELECT b.subjectCode,b.subjectName,b.credit,b.prequisite,s.matricsNo "
                    + "FROM bitm b, student s "
                    + "WHERE b.subjectCode = ? AND b.subjectName = ? AND s.matricsNo = ?";

            ps = con.prepareStatement(sql1);
            ps.setString(1, sbjC);
            ps.setString(2, sbjN);
            ps.setString(3, matNo);
            ps.executeUpdate();

Answer 3

为了回答我自己的问题，我将对我对代码所做的更改发表评论并使其生效：

Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","aza","jaiza");

stmt = con.createStatement();

String sbjC = sbjCode.getText();
String sbjN = sbjName.getText();
String matricsno = textstudentid.getText();
String sbjG = sbjGrade.getText();

String sql1 = "INSERT INTO transferred (subjectCode,subjectName,credit,prequisite,matricsNo) "
        + "SELECT b.subjectCode,b.subjectName,b.credit,b.prequisite,s.matricsNo "
        + "FROM bitm b, student s "
        + "WHERE b.subjectCode = ? AND b.subjectName = ? AND s.matricsNo = ?"; // from textfield to ?

ps = con.prepareStatement(sql1);

ps.setString(1, sbjC);
ps.setString(2, sbjN);
ps.setString(3, matricsno);

//from all the SELECT statement to just 3 user-input-from-textfield column

ps.executeUpdate(); // remove the sql1 in ps.executeUpdate(sql1);