我正在尝试使用for循环语句，如下所示：
for(int i=1; i <= 48; i++) { insertdiary("", ""); }
在我的MyDB文件中：
package com.cookbook.data;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.util.Log;
public class MyDB {
private SQLiteDatabase db;
private final Context context;
private final MyDBhelper dbhelper;
// Initializes MyDBHelper instance
public MyDB(Context c){
context = c;
dbhelper = new MyDBhelper(context, Constants.DATABASE_NAME, null,
Constants.DATABASE_VERSION);
}
// Closes the database connection
public void close()
{
db.close();
}
// Initializes a SQLiteDatabase instance using MyDBhelper
public void open() throws SQLiteException
{
try {
db = dbhelper.getWritableDatabase();
} catch(SQLiteException ex) {
Log.v("Open database exception caught", ex.getMessage());
db = dbhelper.getReadableDatabase();
}
}
// Saves a diary entry to the database as name-value pairs in ContentValues instance
// then passes the data to the SQLitedatabase instance to do an insert
public long insertdiary(String title, String content)
{
try{
ContentValues newTaskValue = new ContentValues();
newTaskValue.put(Constants.TITLE_NAME, title);
newTaskValue.put(Constants.CONTENT_NAME, content);
newTaskValue.put(Constants.DATE_NAME, java.lang.System.currentTimeMillis());
return db.insert(Constants.TABLE_NAME, null, newTaskValue);
} catch(SQLiteException ex) {
Log.v("Insert into database exception caught",
ex.getMessage());
return -1;
}
}
// updates a diary entry (existing row)
public boolean updateDiaryEntry(String title, long rowId)
{
ContentValues newValue = new ContentValues();
newValue.put(Constants.TITLE_NAME, title);
return db.update(Constants.TABLE_NAME, newValue, Constants.KEY_ID + "=" + rowId, null)>0;
}
// Reads the diary entries from database, saves them in a Cursor class and returns it from the method
public Cursor getdiaries()
{
Cursor c = db.query(Constants.TABLE_NAME, null, null,
null, null, null, null);
return c;
}
}
我的目标是在数据库或表首次创建时创建48个空行，以便我可以进一步更新这些行而不是创建新条目。不幸的是，我尝试使用此代码是不幸的，给我错误或创建比48更多的行。 是否有人可以帮助我利用这些代码在数据库或表第一次创建时创建48行？ 我感谢所有的帮助。 稻谷
答案 0 :(得分：0)
除非确实有一些严格的规则来管理创建48个空行的要求，否则创建它们实际上是绝对错误的做法。当需要将数据插入其中时，根据需要创建它们。
答案 1 :(得分：0)
我最初在mysql中做过这个。创建SQLFiddle时遇到了麻烦，所以我也创建了一个SQLite版本。
有 SQLFiddle 。将随后的所有内容压缩到8K，SQLFiddle限制，是有趣的＆＃39; ; - /
SQLite 版本，除了＆＃39; create table＆＃39;之外完全相同。声明，如果需要，我会提供。这将是一个数据库文件的下载，了解，所有机器都是相同的。如果需要，我还可以提供创建脚本。
<强>目的：
据我所知，这个想法是显示约会＆＃39;那天分为48,30分钟。
要求仅记录实际约会。
我把它描绘成少数部门，在事件发生的白天记录约会。在我的示例数据中，访问的人。
以下是显示约会的查询：
SELECT *
FROM department_appointments_view dav
WHERE dav.the_date = '2014-04-11'
AND dav.department_id = 1
AND dav.time_slot_id BETWEEN 12 AND 20;
以下是示例输出：
appointment_id department_id department_code the_date time_slot_id start_time attendee reason duration
-------------- ------------- --------------- ------------------- ------------ ---------- ----------------- --------------------- ----------
0 1 dept_01 2014-04-11 00:00:00 12 05:30:00 30
0 1 dept_01 2014-04-11 00:00:00 13 06:00:00 30
1 1 dept_01 2014-04-11 00:00:00 14 06:30:00 Catherine Tramell to see you 30
0 1 dept_01 2014-04-11 00:00:00 15 07:00:00 30
2 1 dept_01 2014-04-11 00:00:00 16 07:30:00 Buddy Ackerman to see them 30
0 1 dept_01 2014-04-11 00:00:00 17 08:00:00 30
0 1 dept_01 2014-04-11 00:00:00 18 08:30:00 30
3 1 dept_01 2014-04-11 00:00:00 19 09:00:00 Ivan Drago to visit someone else 30
0 1 dept_01 2014-04-11 00:00:00 20 09:30:00 30
因此，输入约会的主表是：
CREATE TABLE `department_appointments` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`department_id` int(11) NOT NULL,
`the_date` date NOT NULL,
`time_slot_id` int(11) NOT NULL,
`attendee` varchar(128) COLLATE utf8_unicode_ci NOT NULL,
`reason` varchar(128) COLLATE utf8_unicode_ci NOT NULL,
`duration` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `dept_fk` (`department_id`),
CONSTRAINT `dept_fk` FOREIGN KEY (`department_id`) REFERENCES `departments` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
这是 only 表，其中输入了约会信息。
示例数据：
id department_id the_date time_slot_id attendee reason duration
------ ------------- ---------- ------------ ----------------------- --------------------- ----------
1 1 2014-04-11 14 Catherine Tramell to see you 30
2 1 2014-04-11 16 Buddy Ackerman to see them 30
3 1 2014-04-11 19 Ivan Drago to visit someone else 30
我们需要一些支持表：
部门表：
CREATE TABLE `departments` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`department_code` varchar(64) COLLATE utf8_unicode_ci NOT NULL,
`title` varchar(128) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
示例数据：
id department_code title
------ --------------- -----------------------------
1 dept_01 Dept 01 - The Widget Makers
2 dept_02 Dept 02 - For Bar Workers
日历：这只是一个包含日期的表格。我的测试数据是4月份。
CREATE TABLE `the_calendar` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`the_date` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=31 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
Sample data:
id the_date
------ ---------------------
1 2014-04-01 00:00:00
2 2014-04-02 00:00:00
3 2014-04-03 00:00:00
4 2014-04-04 00:00:00
read_only_time_slots 表。它有48行，开始时间。此表格只读，永不更新或复制或任何内容。
CREATE TABLE `read_only_time_slots` (
`time_slot_id` int(11) NOT NULL,
`start_time` time NOT NULL,
`duration` int(11) NOT NULL,
PRIMARY KEY (`time_slot_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
示例数据：
time_slot_id start_time duration
------------ ---------- ----------
1 00:00:00 30
2 00:30:00 30
3 01:00:00 30
----------------------
您现在需要一些查询才能运行此批次。请注意，我们会利用数据库引擎尽可能地执行笛卡儿产品。它将从上面的表中为我们生成所有需要的行。
现在，为了简化信息的使用，我使用了＆＃39;观看＆＃39;。这样对我来说不那么困惑。
观看次数
第一个是： time_slot_view
CREATE VIEW `time_slot_view` AS (
SELECT ts.time_slot_id AS time_slot_id,
ts.start_time AS start_time,
ts.duration AS duration
FROM read_only_time_slots ts
ORDER BY ts.time_slot_id ASC)
接下来是： department_calendar_view
每天为每个部门返回空时隙。
CREATE VIEW `department_calendar_view` AS (
SELECT
`d`.`id` AS `department_id`,
`d`.`department_code` AS `department_code`,
`c`.`the_date` AS `the_date`,
`tsv`.`time_slot_id` AS `time_slot_id`,
`tsv`.`start_time` AS `start_time`,
`tsv`.`duration` AS `duration`
FROM ((`the_calendar` `c`
JOIN `time_slot_view` `tsv`)
JOIN `departments` `d`)
ORDER BY `d`.`department_code`,`c`.`the_date`,`tsv`.`time_slot_id`)
最后：有一个使用以上所有内容的视图：
： department_appointments_view
这可能可以作为外部联接来完成。我刚刚使用了两个查询和一个联合。
CREATE VIEW `department_appointments_view` AS
SELECT da.id AS appointment_id,
dcv.`department_id` AS department_id,
dcv.`department_code` AS department_code,
da.`the_date` AS the_date,
da.`time_slot_id` AS time_slot_id,
dcv.start_time AS start_time,
da.`attendee` AS attendee,
da.`reason` AS reason,
da.`duration` AS duration
FROM
`department_appointments` AS da
INNER JOIN department_calendar_view AS dcv
ON da.department_id = dcv.department_id
AND da.the_date = dcv.the_date
AND da.time_slot_id = dcv.time_slot_id
UNION
SELECT 0,
dcv.department_id,
dcv.`department_code` ,
dcv.the_date,
dcv.time_slot_id,
dcv.start_time,
'' AS attendee,
'' AS reason,
dcv.`duration`
FROM department_calendar_view AS dcv
WHERE NOT EXISTS (SELECT 1
FROM `department_appointments` AS da
WHERE da.department_id = dcv.department_id
AND da.the_date = dcv.the_date
AND da.time_slot_id = dcv.time_slot_id)
ORDER BY department_code, the_date, time_slot_id;