Question

我的表遇到问题，第一个表创建了对第二个表中数据的引用，CARD_ID增量很好，但CARD_INFO_TABLE中的外键不会自动增量甚至意识到它是自动增量的外键，所以我想知道，我哪里错了！？

    public static final String CREATE_CARD_TABLE = "CREATE TABLE "
        + CARD_TABLE + "(" + CARD_ID
        + " INTEGER PRIMARY KEY AUTOINCREMENT, " + CARD_NAME
        + " TEXT )";

    public static final String CREATE_CARDINFO_TABLE = "CREATE TABLE "
        + CARD_INFO_TABLE + "(" + CARD_ID2
        + " INTEGER, " + CARD_NAME2
        + " TEXT, " + CARD_WEIGHT
        + " REAL, " + CARD_REPS
        + " INTEGER, "
        + " FOREIGN KEY " + "("+ CARD_ID2 +")"+ " REFERENCES " + CARD_TABLE + "("+CARD_ID+"));";

然后我按如下方式向他们插入数据，我哪里错了？

public void insertEntry(String name, double weight, int reps) {
    if(flag == 0) {
        open();
        database.beginTransaction();
        ContentValues newValues = new ContentValues();
        // Assign values for each row.
        newValues.put(DataBaseHelper.CARD_NAME, name);

        // Insert the row into your table
        database.insert(DataBaseHelper.CARD_TABLE, null, newValues);
        flag = 1;
        database.setTransactionSuccessful();
        database.endTransaction();
        close();
    }
    open();
    database.beginTransaction();
    ContentValues newValues2 = new ContentValues();
    // Assign values for each row.
    newValues2.put(DataBaseHelper.CARD_NAME2, name);
    newValues2.put(DataBaseHelper.CARD_WEIGHT, weight);
    newValues2.put(DataBaseHelper.CARD_REPS, reps);

    // Insert the row into your table
    database.insert(DataBaseHelper.CARD_INFO_TABLE, null, newValues2);
    database.setTransactionSuccessful();
    database.endTransaction();
    close();
}

Answer 1

foreign key constraint只是一个约束，即它只会检查您对数据所做的更改是否会造成错误的关系。

要创建这些关系，您仍然需要插入相同的数据（并且您不应该将操作分成两个事务，并且必须正确处理异常）：

database.beginTransaction();
try {
    long cardID = DatabaseUtils.longForQuery(database,
                    "SELECT "+CARD_ID+" FROM "+CARD_TABLE+
                    " WHERE "+CARD_NAME+" = ?",
                    new String[] { name });
    if (cardID < 0) { // not found?
        ContentValues card = new ContentValues();
        card.put(DataBaseHelper.CARD_NAME, name);
        cardID = database.insert(DataBaseHelper.CARD_TABLE, null, card);
    }

    ContentValues info = new ContentValues();
    info.put(DataBaseHelper.CARD_ID2, cardID);
    info.put(DataBaseHelper.CARD_NAME2, name);
    info.put(DataBaseHelper.CARD_WEIGHT, weight);
    info.put(DataBaseHelper.CARD_REPS, reps);
    database.insert(DataBaseHelper.CARD_INFO_TABLE, null, info);

    database.setTransactionSuccessful();
} finally {
    database.endTransaction();
}

我的外键不起作用？

1 个答案: