java 如何在java中添加自动增量列？
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How to add an auto increment column in java?
提问by Ankush Tyagi
I want to add the database from my jform and there's a column which will be auto incremented, like when i click done, the data will be inserted and a column receipt_nowill have a value 1. Next time I click done then this value should be 2 and so on.
我想从我的 jform 添加数据库，并且有一列会自动增加，就像当我点击完成时，数据将被插入并且一列receipt_no的值是 1。下次我点击完成时，这个值应该是 2等等。
So the problem is, i have created a table with receipt_no as the primary key and auto increment, so what should be my query in java, to add the data correctly in the table.
所以问题是，我创建了一个以receipt_no作为主键和自动增量的表，那么我在java中的查询应该是什么，以便在表中正确添加数据。
String sql = "insert into table_name values('"++"',...)";
Can you help me in this query?
你能帮我完成这个查询吗？
回答by Vicky Thakor
Step 1:Creating table in MySQL
第 1 步：在 MySQL 中创建表
CREATE TABLE `user_master` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`Firstname` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Step 2:Insert record
第二步：插入记录
INSERT INTO user_master (`Firstname`) values('Vicky');
Step 3:Fetch record
第 3 步：获取记录
SELECT * FROM user_master;
回答by Mistalis
I can't comment so there is an answer to the comment you posted in your question:
我无法发表评论，因此您在问题中发表的评论有答案：
If your table is
如果你的桌子是
CREATE TABLE users(
id INT PRIMARY KEY NOT NULL AUTO_INCREMENT,
firstname VARCHAR(25) NOT NULL,
lastname VARCHAR(25) NOT NULL,
);
You can simply auto_increment the primary by not giving it on your SQL request:
您可以通过不在 SQL 请求中提供它来简单地 auto_increment 主：
INSERT INTO users(firstname, lastname) VALUES('Steve', 'Jobs');
Java don't have to generate auto increment, it is SQL job :)
Java 不必生成自动增量，它是 SQL 作业:)
