使用jdbc在Oracle中自动递增列

Question

我想添加一个触发器，它将继续将自动增量列更新 1，因为我认为在 Oracle 中没有直接的方法来自动增量列。你必须使用序列，然后触发触发器，这将更新相应的列。所以我试图在 jdbc 中执行此操作。如何使用准备好的语句自动递增 jdbc 中的列。

    String s1 = "create table crawler " +
                    "(id number NOT NULL PRIMARY KEY, " +
                    "url varchar(255) NOT NULL, " +
                    "urlHash varchar(255) NOT NULL, " +
                    "contentHash varchar(255), " +
                    "modDate varchar(50), " +
                    "contentLocation varchar(100), " +
                    "status integer, " +
                    "lastCrawlDate date) ";

                    String seq = "test_seq";

                    String s2 = "create sequence" + seq + " start with 1 increment by 1 nomaxvalue";
                    String s3 = "create or replace trigger inserttrigger before insert on test for each row begin select test_seq.nextval into :new.id from dual; end;"; 

                    stmt=conn.createStatement();
                    stmt.executeUpdate(s1);
                    stmt.executeUpdate(s2);
                    stmt.executeUpdate(s3);

                    ps = conn.prepareStatement (
                    "INSERT INTO crawler (id, url, urlHash, contentHash, modDate, contentLocation, status, lastCrawlDate) VALUES(?,?,?,?,?,?,?,?)");

//how to write this first value as I know you can increment the column using sequencename.nextval but how to do here in prepared statement.
                    ps.setString (1, seq.nextVal);
                    ps.setString (2, "http://www.google.com");
                    ps.setString (3, "swerrsdfsfdgfgrgthtyty");
                    ps.setString (4, "1a10407d9a7997531aabe53fb367efbc");
                    ps.setString (5, "1a10407d9a7997531aabe53fb367efbc");
                    ps.setString (6, "1a10407d9a7997531aabe53fb367efbc");
                    ps.setString (7, "302");
                    ps.setString (8, "2011-11-27");

Answer 1

您不需要使用触发器。

在您准备好的语句中，sql 可以是：

String insert = "INSERT INTO crawler (id, url, urlHash, contentHash, modDate, contentLocation, status, lastCrawlDate)" 
+ " VALUES(test_seq.nextval,?,?,?,?,?,?,?)";

因此您只需传递其余 7 个参数。

Answer 2

如果您创建触发器，则只需在 INSERT 中省略 ID 列。

ps = conn.prepareStatement (
                    "INSERT INTO crawler (url, urlHash, contentHash, modDate, contentLocation, status, lastCrawlDate) VALUES(?,?,?,?,?,?,?)");
ps.setString (1, "http://www.google.com");
ps.setString (2, "swerrsdfsfdgfgrgthtyty");
ps.setString (3, "1a10407d9a7997531aabe53fb367efbc");
ps.setString (4, "1a10407d9a7997531aabe53fb367efbc");
ps.setString (5, "1a10407d9a7997531aabe53fb367efbc");
ps.setString (6, "302");
ps.setString (7, "2011-11-27");

或者，您可以跳过创建触发器并仅在 INSERT 中引用序列

ps = conn.prepareStatement (
                    "INSERT INTO crawler (id, url, urlHash, contentHash, modDate, contentLocation, status, lastCrawlDate) VALUES(test_seq.nextval,?,?,?,?,?,?,?)");
ps.setString (1, "http://www.google.com");
ps.setString (2, "swerrsdfsfdgfgrgthtyty");
ps.setString (3, "1a10407d9a7997531aabe53fb367efbc");
ps.setString (4, "1a10407d9a7997531aabe53fb367efbc");
ps.setString (5, "1a10407d9a7997531aabe53fb367efbc");
ps.setString (6, "302");
ps.setString (7, "2011-11-27");