android - SQLiteDatabase 方法返回值的差别

Question

数据库操作的返回值类型为什么有的是 long，有的是 int ？

例如：

• insert 返回的是 long：

/**
     * Convenience method for inserting a row into the database.
     *
     * @param table the table to insert the row into
     * @param nullColumnHack optional; may be <code>null</code>.
     *            SQL doesn't allow inserting a completely empty row without
     *            naming at least one column name.  If your provided <code>values</code> is
     *            empty, no column names are known and an empty row can't be inserted.
     *            If not set to null, the <code>nullColumnHack</code> parameter
     *            provides the name of nullable column name to explicitly insert a NULL into
     *            in the case where your <code>values</code> is empty.
     * @param values this map contains the initial column values for the
     *            row. The keys should be the column names and the values the
     *            column values
     * @return the row ID of the newly inserted row, or -1 if an error occurred
     */
    public long insert(String table, String nullColumnHack, ContentValues values) {
        try {
            return insertWithOnConflict(table, nullColumnHack, values, CONFLICT_NONE);
        } catch (SQLException e) {
            Log.e(TAG, "Error inserting " + values, e);
            return -1;
        }
    }

• delete 返回的是 int：

/**
     * Convenience method for deleting rows in the database.
     *
     * @param table the table to delete from
     * @param whereClause the optional WHERE clause to apply when deleting.
     *            Passing null will delete all rows.
     * @param whereArgs You may include ?s in the where clause, which
     *            will be replaced by the values from whereArgs. The values
     *            will be bound as Strings.
     * @return the number of rows affected if a whereClause is passed in, 0
     *         otherwise. To remove all rows and get a count pass "1" as the
     *         whereClause.
     */
    public int delete(String table, String whereClause, String[] whereArgs) {
        acquireReference();
        try {
            SQLiteStatement statement =  new SQLiteStatement(this, "DELETE FROM " + table +
                    (!TextUtils.isEmpty(whereClause) ? " WHERE " + whereClause : ""), whereArgs);
            try {
                return statement.executeUpdateDelete();
            } finally {
                statement.close();
            }
        } finally {
            releaseReference();
        }
    }

Answer 1

@return the row ID of the newly inserted row, or -1 if an error occurred

@return the number of rows affected if a whereClause is passed in, 0 otherwise. To remove all rows and get a count pass "1" as the whereClause.

英文注释的应该还是挺清楚的吧。