Sau khi xem qua các câu trả lời khác, nó đã giúp tôi nhận ra một vấn đề cơ bản.
Cả bảng bài viết và bảng article_images đều cần phải có một chỉ mục bổ sung.
Đây là những gì bạn có bây giờ:
CREATE TABLE `articles` (
`id` int(10) unsigned not null auto_increment,
`author_id` int(10) unsigned not null,
`date_created` datetime not null,
PRIMARY KEY(id)
) ENGINE=InnoDB;
CREATE TABLE `article_images` (
`article_id` int(10) unsigned not null,
`filename` varchar(100) not null,
`date_added` datetime not null,
UNIQUE INDEX(article_id, filename)
) ENGINE=InnoDB;
Đây là những gì bạn cần:
CREATE TABLE `articles` (
`id` int(10) unsigned not null auto_increment,
`author_id` int(10) unsigned not null,
`date_created` datetime not null,
PRIMARY KEY(id),
INDEX (date_created DESC)
) ENGINE=InnoDB;
CREATE TABLE `article_images` (
`article_id` int(10) unsigned not null,
`filename` varchar(100) not null,
`date_added` datetime not null,
UNIQUE INDEX (article_id, filename),
INDEX (article_id, date_added),
) ENGINE=InnoDB;
các bài báo
Chỉ mục mới để sắp xếp các bài báo theo ngày chèn theo thứ tự giảm dần
article_images
Chỉ mục đầu tiên vẫn cần thiết vì nó sẽ ngăn chặn việc đính kèm hình ảnh khác có cùng tên tệp vào một bài báo.
Chỉ mục thứ hai sẽ giúp việc tìm kiếm hình ảnh gần đây nhất trở nên đơn giản,
Với các chỉ mục mới đó, đây là truy vấn sẽ thực hiện việc đặt giá thầu của bạn:
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
Mục tiêu đầu tiên là tạo một truy vấn con nội bộ chỉ có 40 hàng. Đó là những gì AA nên mang lại. Truy vấn con AAA phải có thông tin bài viết cộng với ngày hình ảnh cuối cùng được chèn. Tập hợp các phép nối cuối cùng phải kết nối 40 id với tiêu đề và hình ảnh. Bước cuối cùng là trình bày tập hợp kết quả theo thứ tự giảm dần.
Vì tôi không có dữ liệu mẫu, tôi đã viết ba quy trình được lưu trữ trong cơ sở dữ liệu mẫu có tên là công cụ
1 để tạo bảng
DELIMITER $$
DROP PROCEDURE IF EXISTS `stuff`.`MakeTables` $$
CREATE PROCEDURE `stuff`.`MakeTables` ()
BEGIN
DROP TABLE IF EXISTS articles;
DROP TABLE IF EXISTS article_contents;
DROP TABLE IF EXISTS article_images;
CREATE TABLE `articles` (
`id` int(10) unsigned not null auto_increment,
`author_id` int(10) unsigned not null,
`date_created` datetime not null,
PRIMARY KEY(id),
INDEX (date_created DESC)
) ENGINE=InnoDB;
CREATE TABLE `article_contents` (
`article_id` int(10) unsigned not null,
`title` varchar(100) not null,
`content` text not null,
PRIMARY KEY(article_id)) ENGINE=InnoDB;
CREATE TABLE `article_images` (
`article_id` int(10) unsigned not null,
`filename` varchar(100) not null,
`date_added` datetime not null,
UNIQUE INDEX (article_id, filename),
INDEX (article_id, date_added)
) ENGINE=InnoDB;
END $$
DELIMITER ;
1 để tạo dữ liệu
DELIMITER $$
DROP PROCEDURE IF EXISTS `stuff`.`LoadSampleData` $$
CREATE PROCEDURE `stuff`.`LoadSampleData` ()
BEGIN
DECLARE x,y,z INT;
SET x = 1;
WHILE x <= 100 DO
INSERT INTO articles (author_id,date_created) VALUES
(RAND() * POWER(2,31),
DATE('1970-01-01 00:00:00') + INTERVAL (RAND() * POWER(2,30)) SECOND);
SET x = x + 1;
END WHILE;
SET x = 1;
WHILE x <= 100 DO
SET y = FLOOR(RAND() * 100);
IF y >= 30 THEN
INSERT INTO article_contents
VALUES (x,
CONCAT('TITLE_',FLOOR(RAND() * POWER(2,31))),
CONCAT('CONTENT_',FLOOR(RAND() * POWER(2,31))));
END IF;
SET x = x + 1;
END WHILE;
SET x = 1;
WHILE x <= 100 DO
SELECT COUNT(1) INTO y FROM article_contents WHERE article_id = x;
IF y = 1 THEN
SET y = 0;
WHILE y < 20 DO
SET y = y + 1;
SET z = FLOOR(RAND() * 10);
IF z >= 5 THEN
INSERT INTO article_images
VALUES (x,
CONCAT('IMAGE_',FLOOR(RAND() * POWER(2,31))),
DATE('1970-01-01 00:00:00') + INTERVAL (RAND() * POWER(2,30)) SECOND);
END IF;
END WHILE;
END IF;
SET x = x + 1;
END WHILE;
SELECT COUNT(1) INTO x FROM articles;
SELECT COUNT(1) INTO y FROM article_contents;
SELECT COUNT(1) INTO z FROM article_images;
SELECT CONCAT('Articles:',x,' Titles:',y,' Images: ',z) Results;
END $$
DELIMITER ;
1 để chạy truy vấn
DELIMITER $$
DROP PROCEDURE IF EXISTS `stuff`.`ShowLast40` $$
CREATE PROCEDURE `stuff`.`ShowLast40` ()
BEGIN
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
END $$
DELIMITER ;
Đây là ví dụ đầu ra khi tôi chạy nó trên Máy tính để bàn Windows của mình (MySQL 5.5.12):
mysql> call maketables; call loadsampledata;
Query OK, 0 rows affected (0.31 sec)
+------------------------------------+
| Results |
+------------------------------------+
| Articles:100 Titles:67 Images: 666 |
+------------------------------------+
1 row in set (23.73 sec)
mysql> call showlast40;
+------------+---------------------+------------------+------------------+
| author_id | date_created | title | filename |
+------------+---------------------+------------------+------------------+
| 1576679519 | 2004-01-02 14:05:17 | TITLE_1757853515 | IMAGE_1601858163 |
| 992840519 | 2003-05-17 05:48:11 | TITLE_319026350 | IMAGE_1913708631 |
| 1366977197 | 2003-03-20 19:37:23 | <NO_TITLE> | <NO-IMAGE> |
| 1705517382 | 2003-02-07 16:48:56 | <NO_TITLE> | <NO-IMAGE> |
| 1529899841 | 2002-11-02 20:59:26 | <NO_TITLE> | <NO-IMAGE> |
| 1756824942 | 2002-08-28 16:01:59 | <NO_TITLE> | <NO-IMAGE> |
| 175825630 | 2002-05-08 13:48:56 | TITLE_240812804 | IMAGE_1214850809 |
| 757530551 | 2002-02-08 00:20:17 | TITLE_4447486 | IMAGE_1511850161 |
| 840251261 | 2002-01-25 20:06:56 | TITLE_1160842143 | IMAGE_206027488 |
| 964653347 | 2001-12-26 19:15:47 | TITLE_1552408257 | IMAGE_717719932 |
| 2106039126 | 2001-11-11 17:09:29 | <NO_TITLE> | <NO-IMAGE> |
| 2085991608 | 2001-08-01 12:48:20 | <NO_TITLE> | <NO-IMAGE> |
| 1895462094 | 2000-12-02 05:31:41 | <NO_TITLE> | <NO-IMAGE> |
| 1589384729 | 2000-04-28 23:55:50 | TITLE_1040850308 | IMAGE_1200414639 |
| 514341550 | 2000-04-20 07:25:05 | TITLE_188288840 | IMAGE_164856430 |
| 887359583 | 2000-02-13 03:30:47 | <NO_TITLE> | <NO-IMAGE> |
| 1156687499 | 1999-06-16 00:29:17 | TITLE_686398996 | IMAGE_670200418 |
| 1561242593 | 1998-12-08 05:50:17 | <NO_TITLE> | <NO-IMAGE> |
| 1117889993 | 1998-10-23 17:02:44 | TITLE_1491217221 | IMAGE_649630126 |
| 740063135 | 1998-09-16 23:52:41 | TITLE_579374776 | IMAGE_757313192 |
| 429699232 | 1998-04-19 01:41:17 | TITLE_73748980 | IMAGE_1881818111 |
| 1827051060 | 1998-02-27 01:01:50 | TITLE_1588619991 | IMAGE_1657322715 |
| 1442984429 | 1997-11-19 21:23:35 | TITLE_184173382 | IMAGE_597809368 |
| 152267158 | 1997-05-02 20:25:50 | <NO_TITLE> | <NO-IMAGE> |
| 1323598169 | 1997-03-14 16:30:38 | TITLE_1355869397 | IMAGE_1058313818 |
| 66122740 | 1997-01-05 15:12:20 | TITLE_1259073183 | IMAGE_198280936 |
| 5161474 | 1996-06-28 10:47:26 | TITLE_1876022823 | IMAGE_1138098675 |
| 1865082792 | 1996-03-01 19:09:11 | TITLE_1288151615 | IMAGE_245974646 |
| 1923481146 | 1995-08-07 00:36:11 | TITLE_922744000 | IMAGE_2067090321 |
| 1725218958 | 1995-03-18 05:15:29 | TITLE_583120586 | IMAGE_592773824 |
| 117806248 | 1995-01-05 02:34:32 | <NO_TITLE> | <NO-IMAGE> |
| 1428777335 | 1993-06-06 01:52:32 | TITLE_661148588 | IMAGE_633345518 |
| 1091245943 | 1993-06-05 05:51:47 | TITLE_1407444563 | IMAGE_538936256 |
| 2088382260 | 1993-03-25 06:03:29 | TITLE_1144364681 | IMAGE_1790013089 |
| 625878569 | 1992-12-21 07:41:26 | TITLE_1319355723 | IMAGE_921580624 |
| 110555110 | 1992-01-01 20:49:59 | <NO_TITLE> | <NO-IMAGE> |
| 1110532475 | 1991-11-20 07:19:32 | <NO_TITLE> | <NO-IMAGE> |
| 1726795146 | 1990-10-09 00:23:44 | TITLE_782624350 | IMAGE_1760322575 |
| 370183888 | 1990-03-30 15:59:17 | <NO_TITLE> | <NO-IMAGE> |
| 1497483317 | 1990-02-19 01:25:41 | TITLE_776483948 | IMAGE_665824222 |
+------------+---------------------+------------------+------------------+
40 rows in set (0.00 sec)
Hãy thử !!!
CẬP NHẬT
Tôi hoàn toàn đảm bảo rằng 40 lịch hẹn hò mà bạn đang đọc trên thực tế là 40 lịch hàng đầu. Tôi đã chạy truy vấn:select * từ các bài viết ORDER BY date_create DESC; để đảm bảo.
CẬP NHẬT 2011/05/17 14:06
mysql> call maketables; call loadsampledata;
Query OK, 0 rows affected (0.45 sec)
+-------------------------------------+
| Results |
+-------------------------------------+
| Articles:100 Titles:67 Images: 6739 |
+-------------------------------------+
1 row in set (3 min 45.45 sec)
Query OK, 0 rows affected (3 min 45.45 sec)
mysql> call showlast40;
+------------+---------------------+------------------+------------------+
| author_id | date_created | title | filename |
+------------+---------------------+------------------+------------------+
| 196582776 | 2004-01-05 14:09:04 | <NO_TITLE> | <NO-IMAGE> |
| 1880371016 | 2003-07-31 05:50:37 | TITLE_1191518827 | IMAGE_1562208019 |
| 22204986 | 2003-02-16 14:09:22 | <NO_TITLE> | <NO-IMAGE> |
| 355490160 | 2002-11-21 02:35:19 | <NO_TITLE> | <NO-IMAGE> |
| 869510149 | 2001-12-27 22:07:52 | TITLE_1528616779 | IMAGE_223327284 |
| 2063556512 | 2001-04-16 18:47:46 | TITLE_1839975091 | IMAGE_1282187005 |
| 529754190 | 2000-07-14 19:44:01 | TITLE_1557423205 | IMAGE_1931606737 |
| 166226262 | 1999-11-08 03:27:22 | <NO_TITLE> | <NO-IMAGE> |
| 1981417562 | 1999-09-11 12:59:10 | TITLE_198262896 | IMAGE_1491273871 |
| 831057001 | 1999-06-14 15:06:31 | TITLE_1170272131 | IMAGE_760396200 |
| 1454252623 | 1998-06-02 08:35:46 | <NO_TITLE> | <NO-IMAGE> |
| 1435450777 | 1997-11-17 18:10:34 | TITLE_482497458 | IMAGE_1331932705 |
| 1536315541 | 1997-11-02 05:24:49 | <NO_TITLE> | <NO-IMAGE> |
| 2078028530 | 1997-03-14 22:36:58 | TITLE_321332010 | IMAGE_1897983295 |
| 701651581 | 1997-01-13 22:36:58 | TITLE_1337390701 | IMAGE_1630983859 |
| 101442444 | 1996-11-22 09:40:16 | <NO_TITLE> | <NO-IMAGE> |
| 51114930 | 1996-11-20 03:24:49 | TITLE_1866751135 | IMAGE_1669595407 |
| 722056183 | 1996-08-03 15:23:01 | <NO_TITLE> | <NO-IMAGE> |
| 1178720989 | 1996-06-29 22:47:19 | TITLE_579734376 | IMAGE_833229222 |
| 511355958 | 1996-03-10 09:32:46 | TITLE_1540275289 | IMAGE_1168117261 |
| 831921829 | 1996-01-31 06:36:04 | TITLE_661038882 | IMAGE_1199197195 |
| 1288455163 | 1995-08-22 00:34:25 | TITLE_1599332515 | IMAGE_822445764 |
| 1976208956 | 1995-06-02 09:23:01 | TITLE_58372998 | IMAGE_793318650 |
| 2092066982 | 1995-03-28 20:35:37 | TITLE_1693142377 | IMAGE_1176935479 |
| 1083841549 | 1994-07-11 18:46:52 | TITLE_1955674591 | IMAGE_1240485919 |
| 359037132 | 1994-07-11 02:44:19 | TITLE_713454936 | IMAGE_1072569732 |
| 1471985773 | 1994-05-10 17:08:01 | TITLE_1065017724 | IMAGE_393097704 |
| 1888864730 | 1994-01-15 17:41:28 | TITLE_1060275498 | IMAGE_230810100 |
| 1688028488 | 1993-12-28 06:36:58 | <NO_TITLE> | <NO-IMAGE> |
| 1739777948 | 1993-02-15 00:30:31 | TITLE_1226842225 | IMAGE_1615058467 |
| 445721334 | 1991-12-15 20:54:49 | TITLE_1336145587 | IMAGE_2114729323 |
| 1661002442 | 1991-06-30 05:49:34 | TITLE_151142910 | IMAGE_1623325381 |
| 2092223006 | 1991-06-13 13:15:58 | TITLE_33175860 | IMAGE_1225117771 |
| 1553434585 | 1991-01-12 03:34:25 | TITLE_728483442 | IMAGE_1954153339 |
| 528544608 | 1990-11-10 08:21:04 | <NO_TITLE> | <NO-IMAGE> |
| 1043927395 | 1990-10-05 00:48:49 | TITLE_304307448 | IMAGE_1702062493 |
| 1685702960 | 1990-04-28 05:44:19 | TITLE_1909853341 | IMAGE_263553036 |
| 1392428383 | 1990-03-07 15:08:46 | <NO_TITLE> | <NO-IMAGE> |
| 643714153 | 1990-02-14 08:32:10 | TITLE_837416724 | IMAGE_1673964259 |
| 2132028206 | 1989-09-28 16:04:07 | TITLE_614908878 | IMAGE_1362210487 |
+------------+---------------------+------------------+------------------+
40 rows in set (0.01 sec)
Mọi thứ hoạt động như tôi đã xuất bản trước đây ngay cả với một bộ hình ảnh lớn hơn. Đây là truy vấn từ Thủ tục được lưu trữ ShowLast40:
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
CẬP NHẬT 2011/05/17 15:16
Chỉ để gây cười, tôi đã tăng mẫu và chỉnh sửa nó. Tốc độ truy vấn giống nhau.
mysql> call maketables; call loadsampledata; call showlast40;
Query OK, 0 rows affected (0.38 sec)
+----------------------------------------+
| Results |
+----------------------------------------+
| Articles:1000 Titles:886 Images: 88596 |
+----------------------------------------+
1 row in set (51 min 22.29 sec)
Query OK, 0 rows affected (51 min 22.29 sec)
+------------+---------------------+------------------+------------------+
| author_id | date_created | title | filename |
+------------+---------------------+------------------+------------------+
| 1464539515 | 2004-01-07 22:45:04 | TITLE_676010724 | IMAGE_1877060293 |
| 272558724 | 2004-01-03 23:44:19 | TITLE_1213504045 | IMAGE_550812606 |
| 2000476448 | 2003-12-28 18:05:10 | TITLE_1762951489 | IMAGE_1201290847 |
| 955209697 | 2003-12-25 00:55:43 | TITLE_1064749344 | IMAGE_1335865507 |
| 1657429856 | 2003-12-19 01:03:13 | TITLE_1931852743 | IMAGE_905288424 |
| 759381001 | 2003-11-12 10:46:52 | TITLE_878255772 | IMAGE_2014780795 |
| 1269478951 | 2003-11-06 02:06:22 | TITLE_2026098781 | IMAGE_982272966 |
| 1049672131 | 2003-10-04 20:55:34 | TITLE_2043080215 | IMAGE_987859662 |
| 1429108729 | 2003-09-16 19:07:52 | TITLE_424483080 | IMAGE_35379150 |
| 1672198676 | 2003-09-13 11:49:52 | TITLE_1131552745 | IMAGE_875049630 |
| 1645878842 | 2003-08-24 13:42:04 | TITLE_1077302833 | IMAGE_702269538 |
| 172347180 | 2003-08-21 14:26:37 | TITLE_558691044 | IMAGE_1091183587 |
| 1137674509 | 2003-08-15 08:44:37 | TITLE_1982979709 | IMAGE_1234487941 |
| 282998112 | 2003-08-05 10:01:34 | TITLE_353831568 | IMAGE_738487608 |
| 246145344 | 2003-08-02 00:42:31 | TITLE_376954044 | IMAGE_1279375459 |
| 218409162 | 2003-07-14 02:55:16 | TITLE_1932540991 | IMAGE_1078689211 |
| 593263087 | 2003-07-12 22:47:01 | TITLE_1604012533 | IMAGE_834822870 |
| 2115914174 | 2003-07-06 03:06:31 | TITLE_1268165545 | IMAGE_1068632322 |
| 552557275 | 2003-07-01 16:45:22 | TITLE_2022112717 | IMAGE_1410588295 |
| 1500437041 | 2003-06-29 20:05:19 | TITLE_35559258 | IMAGE_159953586 |
| 1098371257 | 2003-06-09 07:29:37 | TITLE_1694076415 | IMAGE_1409619391 |
| 1570373503 | 2003-05-22 16:45:04 | TITLE_125157894 | IMAGE_723393492 |
| 1330507411 | 2003-05-05 21:40:07 | TITLE_1571250589 | IMAGE_701840418 |
| 1666035620 | 2003-04-26 02:51:40 | TITLE_504713706 | IMAGE_1410357553 |
| 1458179791 | 2003-04-19 05:34:25 | <NO_TITLE> | <NO-IMAGE> |
| 1365758305 | 2003-03-28 10:09:58 | TITLE_704554170 | IMAGE_2085080137 |
| 2131082774 | 2003-03-26 16:43:25 | TITLE_1411034929 | IMAGE_303539208 |
| 103396632 | 2003-02-14 09:11:28 | TITLE_915927396 | IMAGE_1381045723 |
| 396479202 | 2003-02-01 15:51:40 | <NO_TITLE> | <NO-IMAGE> |
| 2019916250 | 2003-01-30 00:44:46 | <NO_TITLE> | <NO-IMAGE> |
| 431091906 | 2003-01-29 13:08:37 | <NO_TITLE> | <NO-IMAGE> |
| 705166549 | 2003-01-23 21:37:07 | TITLE_1530318643 | IMAGE_257673696 |
| 1278327049 | 2002-12-31 16:39:40 | TITLE_772845324 | IMAGE_1355754913 |
| 1871174528 | 2002-12-30 19:03:40 | TITLE_65725764 | IMAGE_522904938 |
| 611892727 | 2002-12-22 10:19:07 | TITLE_333758274 | IMAGE_734815032 |
| 758497849 | 2002-12-04 15:05:10 | TITLE_129140574 | IMAGE_244407066 |
| 518111034 | 2002-10-17 16:38:10 | TITLE_1976498683 | IMAGE_2008599775 |
| 1737725786 | 2002-10-15 23:52:52 | TITLE_1441053871 | IMAGE_1595265847 |
| 1206055789 | 2002-10-03 22:07:52 | TITLE_562697952 | IMAGE_198940092 |
| 702790153 | 2002-08-31 17:37:16 | TITLE_1788304903 | IMAGE_1212944101 |
+------------+---------------------+------------------+------------------+
40 rows in set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
CẬP NHẬT 2011/05/17 15:40
Đây là kết quả mới bao gồm ngày của hình ảnh mới nhất:
mysql> call showlast40;
+------------+---------------------+------------------+------------------+---------------------+
| author_id | date_created | title | filename | image_date |
+------------+---------------------+------------------+------------------+---------------------+
| 1464539515 | 2004-01-07 22:45:04 | TITLE_676010724 | IMAGE_1877060293 | 2003-10-16 02:06:58 |
| 272558724 | 2004-01-03 23:44:19 | TITLE_1213504045 | IMAGE_550812606 | 2003-12-28 07:25:43 |
| 2000476448 | 2003-12-28 18:05:10 | TITLE_1762951489 | IMAGE_1201290847 | 2003-08-31 16:56:01 |
| 955209697 | 2003-12-25 00:55:43 | TITLE_1064749344 | IMAGE_1335865507 | 2003-11-11 18:37:07 |
| 1657429856 | 2003-12-19 01:03:13 | TITLE_1931852743 | IMAGE_905288424 | 2003-09-26 07:20:01 |
| 759381001 | 2003-11-12 10:46:52 | TITLE_878255772 | IMAGE_2014780795 | 2003-09-30 06:54:40 |
| 1269478951 | 2003-11-06 02:06:22 | TITLE_2026098781 | IMAGE_982272966 | 2003-07-28 11:59:10 |
| 1049672131 | 2003-10-04 20:55:34 | TITLE_2043080215 | IMAGE_987859662 | 2003-11-19 05:26:37 |
| 1429108729 | 2003-09-16 19:07:52 | TITLE_424483080 | IMAGE_35379150 | 2003-11-18 22:17:55 |
| 1672198676 | 2003-09-13 11:49:52 | TITLE_1131552745 | IMAGE_875049630 | 2003-06-08 00:42:58 |
| 1645878842 | 2003-08-24 13:42:04 | TITLE_1077302833 | IMAGE_702269538 | 2002-04-02 01:21:49 |
| 172347180 | 2003-08-21 14:26:37 | TITLE_558691044 | IMAGE_1091183587 | 2003-08-13 08:30:22 |
| 1137674509 | 2003-08-15 08:44:37 | TITLE_1982979709 | IMAGE_1234487941 | 2003-12-17 11:53:28 |
| 282998112 | 2003-08-05 10:01:34 | TITLE_353831568 | IMAGE_738487608 | 2003-11-08 22:03:22 |
| 246145344 | 2003-08-02 00:42:31 | TITLE_376954044 | IMAGE_1279375459 | 2003-12-05 02:30:49 |
| 218409162 | 2003-07-14 02:55:16 | TITLE_1932540991 | IMAGE_1078689211 | 2003-07-14 15:59:37 |
| 593263087 | 2003-07-12 22:47:01 | TITLE_1604012533 | IMAGE_834822870 | 2003-09-02 05:48:22 |
| 2115914174 | 2003-07-06 03:06:31 | TITLE_1268165545 | IMAGE_1068632322 | 2003-04-28 16:29:01 |
| 552557275 | 2003-07-01 16:45:22 | TITLE_2022112717 | IMAGE_1410588295 | 2003-11-01 01:55:16 |
| 1500437041 | 2003-06-29 20:05:19 | TITLE_35559258 | IMAGE_159953586 | 2003-08-02 10:34:07 |
| 1098371257 | 2003-06-09 07:29:37 | TITLE_1694076415 | IMAGE_1409619391 | 2004-01-07 01:00:13 |
| 1570373503 | 2003-05-22 16:45:04 | TITLE_125157894 | IMAGE_723393492 | 2003-09-26 23:22:43 |
| 1330507411 | 2003-05-05 21:40:07 | TITLE_1571250589 | IMAGE_701840418 | 2003-11-19 20:57:31 |
| 1666035620 | 2003-04-26 02:51:40 | TITLE_504713706 | IMAGE_1410357553 | 2003-11-18 01:30:04 |
| 1458179791 | 2003-04-19 05:34:25 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 1365758305 | 2003-03-28 10:09:58 | TITLE_704554170 | IMAGE_2085080137 | 2003-11-11 16:35:19 |
| 2131082774 | 2003-03-26 16:43:25 | TITLE_1411034929 | IMAGE_303539208 | 2003-05-14 12:59:37 |
| 103396632 | 2003-02-14 09:11:28 | TITLE_915927396 | IMAGE_1381045723 | 2003-12-28 18:26:28 |
| 396479202 | 2003-02-01 15:51:40 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 2019916250 | 2003-01-30 00:44:46 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 431091906 | 2003-01-29 13:08:37 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 705166549 | 2003-01-23 21:37:07 | TITLE_1530318643 | IMAGE_257673696 | 2003-08-23 19:06:22 |
| 1278327049 | 2002-12-31 16:39:40 | TITLE_772845324 | IMAGE_1355754913 | 2003-12-22 16:40:25 |
| 1871174528 | 2002-12-30 19:03:40 | TITLE_65725764 | IMAGE_522904938 | 2003-09-06 07:08:01 |
| 611892727 | 2002-12-22 10:19:07 | TITLE_333758274 | IMAGE_734815032 | 2003-09-22 19:16:43 |
| 758497849 | 2002-12-04 15:05:10 | TITLE_129140574 | IMAGE_244407066 | 2003-07-15 12:38:37 |
| 518111034 | 2002-10-17 16:38:10 | TITLE_1976498683 | IMAGE_2008599775 | 2004-01-06 16:37:34 |
| 1737725786 | 2002-10-15 23:52:52 | TITLE_1441053871 | IMAGE_1595265847 | 2003-11-24 15:23:10 |
| 1206055789 | 2002-10-03 22:07:52 | TITLE_562697952 | IMAGE_198940092 | 2003-08-23 11:56:46 |
| 702790153 | 2002-08-31 17:37:16 | TITLE_1788304903 | IMAGE_1212944101 | 2003-12-19 22:56:01 |
+------------+---------------------+------------------+------------------+---------------------+
40 rows in set (0.01 sec)
Đây là truy vấn mới
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename,
IFNULL(CCC.date_added,'<NO-IMAGE-DATE>') image_date
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
Truy vấn của tôi thực hiện một điều mà không ai khác truy vấn làm:
Truy vấn của tôi lấy 40 bài báo cuối cùng trước khi tham gia vào bất kỳ bảng nào khác.
Các truy vấn của mọi người khác sẽ kết hợp mọi thứ trước và sau đó cố gắng thực hiện LIMIT 40 trên một bảng tạm thời lớn.
Thời gian chạy truy vấn của tôi không phải là một yếu tố của lượng dữ liệu.
Bất kể kích thước mẫu tôi tạo là bao nhiêu, truy vấn của tôi phải nhanh nhất !!!
