Константин Цветков

CREATE TABLE Point ( P CHAR(2), X INT, Y INT);
INSERT Point VALUES ( 'A1', 3, 4 ), ( 'A2', 8, 7 );

SELECT CONCAT( PA1.P, PA2.P ), PA2.X - PA1.X, PA2.Y - PA1.Y
  FROM Point AS PA1, Point AS PA2
  WHERE PA1.P = 'A1' AND PA2.P = 'A2'

WHERE ( Val >= ValFrom ) AND (( Val <= ValTo ) OR ( ValTo IS NULL ))

UPDATE dle_post 
  SET category = CONCAT_WS(',' , category, '10' )
  WHERE xfields LIKE '%семейный%' 
    AND ( FIND_IN_SET( '10', category ) = 0 )

SELECT LEFT( Text, LOCATE( 'поиска', Text ) + LENGTH ('поиска') - 1)
  FROM Texts
  WHERE Text LIKE '%поиска%'

CREATE TABLE `author` (
   `id` INT(10) NOT NULL,
   `name` VARCHAR(200) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
   `fam` VARCHAR(200) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
   `birthday` DATE NULL DEFAULT NULL,
   PRIMARY KEY (`id`)
);
 
CREATE TABLE `books` (
   `id` INT(10),
   `id_author` INT(10) NULL DEFAULT NULL,
   `book` VARCHAR(500) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
   PRIMARY KEY (`id`),
   INDEX `id_author` (`id_author`)
);

INSERT INTO `author` (`id`, `name`, `fam`, `birthday`) VALUES (1, 'Николай Николаевич', 'Носов', '2008-11-23');
INSERT INTO `author` (`id`, `name`, `fam`, `birthday`) VALUES (2, 'Артур Конан', 'Дойль', '1859-05-22');
 
INSERT INTO `books` (`id`, `id_author`, `book`) VALUES (1, 1, 'Незнайка учится');
INSERT INTO `books` (`id`, `id_author`, `book`) VALUES (2, 1, 'Незнайка-путешественник');
INSERT INTO `books` (`id`, `id_author`, `book`) VALUES (3, 1, 'Винтик, Шпунтик и пылесос');

SELECT a.id, a.name, a.fam, GROUP_CONCAT(DISTINCT b.book ORDER BY b.book ASC SEPARATOR ', ') AS books
FROM `author` a
LEFT JOIN `books` b ON a.id=b.id_author
GROUP BY a.id;

SELECT a1.object_id 
  FROM activity AS a1
    LEFT JOIN activity AS a2 ON a2.object_id = a1.object_id 
  WHERE a1.subject = "added" AND a2.subject = "remove" AND a2.object_id IS NULL

SQL JOIN

CASE WHEN User_ID1 > User_ID2 THEN CONCAT ( User_ID2, '-', User_ID1 )
  ELSE CONCAT ( User_ID1, '-', User_ID2 )
END CASE

SELECT DISTINCT tag_id FROM news_tag WHERE theme_id = КодСтрогоЗаданнойТемы

потому что он есть в обеих статьях

SELECT tag_id
  FROM news_tag
  WHERE (theme_id = 1)
  GROUP BY tag_id
  HAVING COUNT(news_id) = ( SELECT COUNT(DISTINCT(news_id)) FROM news_tag WHERE (theme_id = 1) )

SELECT MAX(start_diameter) FROM table_name WHERE (start_diameter <= 145)
UNION ALL
SELECT MIN(start_diameter) FROM table_name WHERE (start_diameter >= 145)