java - 如何将数据插入带有外键的表中？

Question

我有两个表:

用户:user_id(PK) |名称
产品:product_id(PK) |产品 | user_id(FK)

这是一种一对多的关系(一个用户可以拥有多个产品)。我使用以下语句创建了表格:

String stmt_user = "create table user (user_id int not null generated by default as identity," 
                   + "name varchar(20), " 
                   + "primary key(user_id))";

String stmt_prod = "create table product (product_id int not null generated by default as identity,"
                   + "product varchar(20), "
                   + "constraint ads_pk primary key(product_id), "
                   + "foreign key(user_id)  references user(user_id) on delete cascade)";

当我想向 ID 为 2 的某个特定用户插入多个产品时，我该怎么办？
像这样:“插入产品值(产品)，其中用户(user_id)= 2”。
我的表格应该是这样的:

|---------------------|------------------|---------------|
|      product_id     |     user_id      |    product    |
|---------------------|------------------|---------------|
|          1          |         2        |     bacon     |
|---------------------|------------------|---------------|
|          2          |         2        |     pizza     |
|---------------------|------------------|---------------|
|          3          |         2        |     beans     |
|---------------------|------------------|---------------|

Answer 1

啊终于从这里找到了我的答案: Insert into table with a foreign key

我必须更新我的创建产品声明:

String stmt_prod = "create table product (product_id int not null generated by default as identity,"
                   + "product varchar(20), "
                   + "constraint ads_pk"
                   + "foreign key(user_id) references user(user_id) on delete cascade)";

现在我的插入产品声明看起来像这样并且效果很好:

"insert into product (product, user_id) select product, u.user_id from user u where u.user_id = 2");