Android sql 语句 分页加载 一次取10 条

String sql10= "select  * from "+Constants.TABLE_MAILS
+ " where "+ Constants.TABLE_MAILS_FOLDER +" =? and "+Constants.TABLE_MAILS_COUNT+" =? "
+" order by "+Constants.CONTACTSID+" desc "+" limit 4,8 ";//4是起始index（0为原点），desc方向取8条数据。所以是【4，8+4-1】=【4,8+4）
//			String sql10="select  * from ( "
//					+ "select  * from "+Constants.TABLE_MAILS
//					+ " where "+ Constants.TABLE_MAILS_FOLDER +" =? and "+Constants.TABLE_MAILS_COUNT+" =? "+" order by "+Constants.CONTACTSID+" desc "+" limit 0,8 "
//					+ " ) order by "+Constants.CONTACTSID+" asc"+" limit 0,4 ";

/**
* 获取 从脚标M_N之间的数据;
*
* 未读和星标邮件待会 处理
* @param folderName
* @param countStr
* @param startIndex
* @return
*/
public List<MailBean> queryIndex10sMailByFName(String folderName,String countStr,int startIndex ) {
Log.i("queryIndexM_NMailByFName", "--------------------------start");
List<MailBean> lists = new ArrayList<MailBean>();
if (folderName.equals("所有未读")) {
return queryNewMailByMsgCount(true, countStr);
}else if (folderName.equals("星标邮件")) {
return queryStarMailByMsgCount(true, countStr);
}
MailBean bean;
Cursor cursor = null;
SQLiteDatabase db = helper.getReadableDatabase();
String sql ="select * from " + Constants.TABLE_MAILS+ " where "+ Constants.TABLE_MAILS_FOLDER +"=? and "+Constants.TABLE_MAILS_COUNT+"=?";
//				+ " ORDER BY " + Constants.KEY_MESSAGE_DATE + " desc";
String selection[] = {folderName,countStr};
cursor = db.rawQuery(sql, selection);

int mailSum=cursor.getCount();
if (mailSum < 1) {
Log.i("queryIndexM_NMailByFName", folderName+"Group is null");
db.close();
cursor.close();
return lists;
} else {
//			String sqlPer10="SELECT TOP 10 * FROM (SELECT TOP 20 * FROM TableName ORDER BY _id ASC) ORDER BY _id DESC";
String sql10= "select  * from "+Constants.TABLE_MAILS
+ " where "+ Constants.TABLE_MAILS_FOLDER +" =? and "+Constants.TABLE_MAILS_COUNT+" =? "
+" order by "+Constants.CONTACTSID+" desc "+" limit 4,8 ";//4是起始index（0为原点），desc方向取8条数据。所以是【4，8+4-1】=【4,8+4）
//			String sql10="select  * from ( "
//					+ "select  * from "+Constants.TABLE_MAILS
//					+ " where "+ Constants.TABLE_MAILS_FOLDER +" =? and "+Constants.TABLE_MAILS_COUNT+" =? "+" order by "+Constants.CONTACTSID+" desc "+" limit 0,8 "
//					+ " ) order by "+Constants.CONTACTSID+" asc"+" limit 0,4 ";
String selPer10[] = {folderName,countStr};
cursor=null;
cursor = db.rawQuery(sql10, selPer10);
int num2=cursor.getCount();
System.out.println("num2  = "+num2);
if (cursor.getCount()<1) {
db.close();
cursor.close();
return lists;
}else {
while (cursor.moveToNext()) {
String count = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_COUNT));
String mailFolder = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_FOLDER));
String msgID = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_MSGUID));
String date = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_DATE));
String from = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_FROM));
String tos = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_TOS));
String ccs = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_CCS));
String subject = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_SUBJECT));
String contentType = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_CONTENTTYPE));
String summary = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_SUMMARY));
String content = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_CONTENT));

boolean isNew = cursor.getInt(cursor.getColumnIndex(Constants.TABLE_MAILS_ISNEW))==1?true:false;
boolean isContainAttach = cursor.getInt(cursor.getColumnIndex(Constants.TABLE_MAILS_ISCONTAINATTACH))==1?true:false;

String attachNames = cursor.getString(cursor.getColumnIndex(Constants.TABLE_MAILS_ATTACHNAMES));

boolean isStar = cursor.getInt(cursor.getColumnIndex(Constants.TABLE_MAILS_ISSTAR))==1?true:false;

boolean isReplySign = cursor.getInt(cursor.getColumnIndex(Constants.TABLE_MAILS_ISREPLAYSIGN))==1?true:false;
bean = new MailBean(count, mailFolder, msgID, date, from, tos, ccs, subject, contentType, summary ,content,
isNew, isContainAttach, attachNames, isStar, isReplySign);

lists.add(bean);
}

}
}
db.close();
cursor.close();
return lists;
}

注意：在使用的降序和升序的时候， order    by ？？？ 这个地方这一列要是integer 类型，不然数据库按照这一列排序。（不能是   varchar（50） 和text）

运行过程：数据库先按照 ？？？ 这一列排序，再取出 【startIndex，endIndex） 之间的数据；备注：【 ， ） 数学里面的开闭区间你懂得



/**
* 创建 邮件 数据列表
* @param db
*/
private void createMailsTable(SQLiteDatabase db){
String sql="create table if not exists "+Constants.TABLE_MAILS+"("
+ Constants.CONTACTSID +" integer primary key autoincrement,"
+ Constants.TABLE_MAILS_COUNT+" text,"
+ Constants.TABLE_MAILS_FOLDER+" text,"
+ Constants.TABLE_MAILS_MSGUID+" integer,"
+ Constants.TABLE_MAILS_DATE+" text,"
+ Constants.TABLE_MAILS_FROM+" text,"
+ Constants.TABLE_MAILS_TOS+" text,"
+ Constants.TABLE_MAILS_CCS+" text,"
+ Constants.TABLE_MAILS_SUBJECT+" text,"
+ Constants.TABLE_MAILS_CONTENTTYPE+" text,"
+ Constants.TABLE_MAILS_SUMMARY+" text,"
+ Constants.TABLE_MAILS_CONTENT+" text,"
+ Constants.TABLE_MAILS_ISNEW+" integer,"
+ Constants.TABLE_MAILS_ISCONTAINATTACH+" integer,"
+ Constants.TABLE_MAILS_ATTACHNAMES+" text,"
+ Constants.TABLE_MAILS_ATTACHNAMES_SDPATH+" text,"
+ Constants.TABLE_MAILS_ISSTAR+" integer,"
+ Constants.TABLE_MAILS_ISREPLAYSIGN+" integer)";
Log.d("Mine 数据库", sql);
db.execSQL(sql);
}