I have a Java webproject with servlets, jsp, java and so on. There I have many projects inside, which I can choose in a combobox like this:
我有一个带有servlets,jsp,java等的Java webproject。我在里面有很多项目,我可以在这样的组合框中选择:
Project [Combobox]
Priority[Combobox] Stage[Combobox]
For each project I can select other values in the combobox Priority and Stage. So we can say, that the values in priority and stage are always in relation with the chosen project.
对于每个项目,我可以在组合框优先级和阶段中选择其他值。所以我们可以说,优先级和阶段的值总是与所选项目有关。
In the database I have tables like this:
在数据库中我有这样的表:
Table project:
projectid
projectname
Table priority
id
priorityname
projectname
Know if i have the value prio1 for the priority and i want to give this value Project 1 and Project 2, i have to do two entries in the database in the table priority: like this
知道我是否具有优先级的值prio1,并且我想给这个值项目1和项目2,我必须在数据库中的表优先级做两个条目:像这样
id priorityname projectname
1 prio1 project1
1 prio1 project2
But i want to do only one entrie the database: So my idea in the database was like this:
但我想只做一个数据库:所以我在数据库中的想法是这样的:
id priorityname projectname
1 prio1 project1,project2
I don't have much experience in this subject. So I wanted to tell you this, maybe my idea isn't good and I hope there is a better solution.
我对这个课程没有多少经验。所以我想告诉你这个,也许我的想法不好,我希望有更好的解决方案。
1 个解决方案
#1
2
You can't insert multiple values in one database-field.
您不能在一个数据库字段中插入多个值。
Depending on your used Database there should be different ways to reach your goal. Try using Foreign Keys if your Database supports them (e.g. MySQL InnoDB
databases do).
根据您使用的数据库,应该有不同的方法来实现您的目标。如果您的数据库支持外键,请尝试使用外键(例如MySQL InnoDB数据库)。
With foreign Keys you'd need to point from your Project
table entries to a Priority
entry. You then can do a SELECT
query, like:
使用外键,您需要从Project表条目指向Priority条目。然后,您可以执行SELECT查询,例如:
SELECT *
FROM projects,
priorities
WHERE projects.proj_priority = priorities.prio_id
AND priorities.prio_name = "prio1"
(assuming)
(假设)
The tables would look like this:
表格如下所示:
projects (proj_id, proj_name, proj_priority)
priorities (prio_id, prio_name)
where proj_id
and prio_id
are the primary keys and proj_priority
is the foreign key.
其中proj_id和prio_id是主键,proj_priority是外键。
#1
2
You can't insert multiple values in one database-field.
您不能在一个数据库字段中插入多个值。
Depending on your used Database there should be different ways to reach your goal. Try using Foreign Keys if your Database supports them (e.g. MySQL InnoDB
databases do).
根据您使用的数据库,应该有不同的方法来实现您的目标。如果您的数据库支持外键,请尝试使用外键(例如MySQL InnoDB数据库)。
With foreign Keys you'd need to point from your Project
table entries to a Priority
entry. You then can do a SELECT
query, like:
使用外键,您需要从Project表条目指向Priority条目。然后,您可以执行SELECT查询,例如:
SELECT *
FROM projects,
priorities
WHERE projects.proj_priority = priorities.prio_id
AND priorities.prio_name = "prio1"
(assuming)
(假设)
The tables would look like this:
表格如下所示:
projects (proj_id, proj_name, proj_priority)
priorities (prio_id, prio_name)
where proj_id
and prio_id
are the primary keys and proj_priority
is the foreign key.
其中proj_id和prio_id是主键,proj_priority是外键。