java使用JDBC从SQL INSERT获取序列

Question

所以我尝试使用文件中的JDBC添加到数据库中。现在当INSERTING我需要在插入之前获取ID，如果数据库仍然使用sequence会更好

在文件夹resources中，我有一个名为insert_plant.sql的文件，其中包含以下查询：

INSERT INTO PLANTS (id, plantname, species)
  VALUES (NEXT VALUE FOR sequence, ?, null);

该表由以下内容生成：

DROP SCHEMA public CASCADE;

CREATE SEQUENCE sequence START WITH 1;

CREATE TABLE PLANTS (
   id BIGINT NOT NULL PRIMARY KEY,
   plantname VARCHAR(255) NOT NULL,
   species VARCHAR(255) NULL,
);

现在在Java中，我称之为：

public static void insertIntoOrderTable(BasicDataSource basicDataSource, String plantname) throws  SQLException{
    Connection conn = null;
    PreparedStatement stmt = null;

    try {
        conn = basicDataSource.getConnection();
        stmt = conn.prepareStatement(Util.readFileFromClasspath("insert_plant.sql"));
        stmt.setString(1, plantname);
        stmt.executeUpdate();

        //Below is the line 57 (in error)
        ResultSet rs = stmt.executeQuery("SELECT sequence.NEXTVAL FROM PLANTS");
        if(rs.next()){
            System.out.println("ID" + rs.getInt(1));
        }

    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (stmt != null) {
            stmt.close();
        }
        if (conn != null) {
            conn.close();
        }
    }
}

我得到的错误是：

java.sql.SQLFeatureNotSupportedException: feature not supported
at org.hsqldb.jdbc.JDBCUtil.notSupported(Unknown Source)
at org.hsqldb.jdbc.JDBCPreparedStatement.executeQuery(Unknown Source)
at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)
at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)
at database.PlantDao.insertIntoOrderTable(PlantDao.java:57)
at database.PlantDao.main(PlantDao.java:19)

所以问题来了

Answer 1

正如“穿刺者”已经评论的那样，不需要执行第二条语句，您可以使用JDBC

PreparedStatement stmt = conn.prepareStatement(sql, new String[]{"id"});

要从中获得价值：

ResultSet rs = stmt.getGeneratedKeys();
if(rs.next()){
    System.out.println(rs.getLong(1));
}

因此，您的方法如下所示：

public static void insertIntoOrderTable(BasicDataSource basicDataSource, String plantname) throws  SQLException{
    Connection conn = null;
    PreparedStatement stmt = null;

    try {
        conn = basicDataSource.getConnection();
        stmt = conn.prepareStatement(Util.readFileFromClasspath("insert_plant.sql"), new String[]{"id"});
        stmt.setString(1, plantname);
        stmt.executeUpdate();

        ResultSet rs = stmt.getGeneratedKeys();
        if(rs.next()){
            System.out.println(rs.getLong(1));
        }

    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (stmt != null) {
            stmt.close();
        }
        if (conn != null) {
            conn.close();
        }
    }
}