SQlite - Android - 外键语法

发布于 2024-10-21 20:37:20 字数 806 浏览 2 评论 0原文

我一直在尝试让外键在我的 Android SQLite 数据库中工作。我已经尝试过以下语法，但它给了我一个强制关闭：

private static final String TASK_TABLE_CREATE = "create table "
            + TASK_TABLE + " (" + TASK_ID
            + " integer primary key autoincrement, " + TASK_TITLE
            + " text not null, " + TASK_NOTES + " text not null, "
    + TASK_DATE_TIME + " text not null, FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+" ("+CAT_ID+"));";

任何想法我可能做错了什么？如果您需要查看其他表结构，那么我可以，它只是第二个表的一个非常简单的结构，带有 ID 和名称。

编辑：

这是错误：

03-13 13:42:35.389: 错误/AndroidRuntime(312)：原因： android.database.sqlite.SQLiteException：国外未知专栏“taskCat” 关键定义：创建表提醒 (_id 整数主键自动增量，task_title 文本不是 null，注释文本不为空，提醒日期时间文本不为空，外键（taskCat）参考类别（_id））；

原文

I've been trying to get foreign keys working within my Android SQLite database. I have tried the following syntax but it gives me a force close:

private static final String TASK_TABLE_CREATE = "create table "
            + TASK_TABLE + " (" + TASK_ID
            + " integer primary key autoincrement, " + TASK_TITLE
            + " text not null, " + TASK_NOTES + " text not null, "
    + TASK_DATE_TIME + " text not null, FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+" ("+CAT_ID+"));";

Any ideas what I might be doing wrong? if you need to see the other table structure then I can, its just a very simple structure for the second with an ID and a name.

Edit:

Here is the error:

03-13 13:42:35.389:
ERROR/AndroidRuntime(312): Caused by:
android.database.sqlite.SQLiteException:
unknown column "taskCat" in foreign
key definition: create table reminders
(_id integer primary key
autoincrement, task_title text not
null, notes text not null,
reminder_date_time text not null,
FOREIGN KEY (taskCat) REFERENCES
category (_id));

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

乙白 2024-10-28 20:37:20

您必须首先定义 TASK_CAT 列，然后在其上设置外键。

private static final String TASK_TABLE_CREATE = "create table "
        + TASK_TABLE + " (" 
        + TASK_ID + " integer primary key autoincrement, " 
        + TASK_TITLE + " text not null, " 
        + TASK_NOTES + " text not null, "
        + TASK_DATE_TIME + " text not null,"
        + TASK_CAT + " integer,"
        + " FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+"("+CAT_ID+"));";

您可以在 sqlite 外键 doc 上找到更多信息。

You have to define your TASK_CAT column first and then set foreign key on it.

private static final String TASK_TABLE_CREATE = "create table "
        + TASK_TABLE + " (" 
        + TASK_ID + " integer primary key autoincrement, " 
        + TASK_TITLE + " text not null, " 
        + TASK_NOTES + " text not null, "
        + TASK_DATE_TIME + " text not null,"
        + TASK_CAT + " integer,"
        + " FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+"("+CAT_ID+"));";

More information you can find on sqlite foreign keys doc.

回复收藏 0 原文

一场春暖 2024-10-28 20:37:20

由于我无法发表评论，因此除了 @jethro 答案之外还添加了此注释。

我发现您还需要将 FOREIGN KEY 行作为创建表语句的最后一部分，否则在安装应用程序时会出现语法错误。我的意思是，你不能做这样的事情：

private static final String TASK_TABLE_CREATE = "create table "
    + TASK_TABLE + " (" + TASK_ID
    + " integer primary key autoincrement, " + TASK_TITLE
    + " text not null, " + TASK_NOTES + " text not null, "
+ TASK_CAT + " integer,"
+ " FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+" ("+CAT_ID+"), "
+ TASK_DATE_TIME + " text not null);";

我将 TASK_DATE_TIME 放在外键行之后。

Since I cannot comment, adding this note in addition to @jethro answer.

I found out that you also need to do the FOREIGN KEY line as the last part of create the table statement, otherwise you will get a syntax error when installing your app. What I mean is, you cannot do something like this:

private static final String TASK_TABLE_CREATE = "create table "
    + TASK_TABLE + " (" + TASK_ID
    + " integer primary key autoincrement, " + TASK_TITLE
    + " text not null, " + TASK_NOTES + " text not null, "
+ TASK_CAT + " integer,"
+ " FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+" ("+CAT_ID+"), "
+ TASK_DATE_TIME + " text not null);";

Where I put the TASK_DATE_TIME after the foreign key line.

回复收藏 0 原文