I have such a tables offers and offer_operating_systems related by offer_id. I made two queris and from my understanding they should return same result, but they don't
Query 1:
select
count(*)
from
`offers`
where
(
select count(*)
from `offer_operating_systems`
where
`offer_operating_systems`.`offer_id` = `offers`.`id`
and
`operating_system` = 'android'
) = 1
order by `id` asc
Query 2:
select
count(*)
from offer_operating_systems
where
operating_system = 'android'
order by `id` asc
Can someone explain to me why the results are not the same? Thanks!
EDITED
operating_systemcolumn is unique so each offer can have only one record with adnroid
Table structures
CREATE TABLE `offers` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`type` int(11) NOT NULL DEFAULT '0',
`url` text COLLATE utf8_unicode_ci,
`status` varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'pending',
`api_created_at` timestamp NULL DEFAULT NULL,
`api_updated_at` timestamp NULL DEFAULT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`),
KEY `offers_status_index` (`status`)
) ENGINE=InnoDB AUTO_INCREMENT=423 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
CREATE TABLE `offer_operating_systems` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`offer_id` int(10) unsigned NOT NULL,
`operating_system` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`),
UNIQUE KEY `offer_operating_systems_offer_id_operating_system_unique` (`offer_id`,`operating_system`),
KEY `offer_operating_systems_offer_id_foreign` (`offer_id`),
CONSTRAINT `offer_operating_systems_offer_id_foreign` FOREIGN KEY (`offer_id`) REFERENCES `offers` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=728 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
Related
I'm try to create table as below, but get error:
Invalid default value for 'updated_at'
I don't know what to do...what's wrong in query.
CREATE TABLE `posts` (
`id` int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
`user_id` int(11) DEFAULT NULL,
`title` varchar(255) NOT NULL,
`slug` varchar(255) NOT NULL UNIQUE,
`views` int(11) NOT NULL DEFAULT '0',
`image` varchar(255) NOT NULL,
`body` text NOT NULL,
`published` tinyint(1) NOT NULL,
`created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
According SQL standard '0000-00-00 00:00:00' is not valid value for timestamp field. You should to use NULL as default value fro updated_at column.
CREATE TABLE `posts` (
`id` int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
`user_id` int(11) DEFAULT NULL,
`title` varchar(255) NOT NULL,
`slug` varchar(255) NOT NULL UNIQUE,
`views` int(11) NOT NULL DEFAULT '0',
`image` varchar(255) NOT NULL,
`body` text NOT NULL,
`published` tinyint(1) NOT NULL,
`created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`updated_at` timestamp NULL ON UPDATE CURRENT_TIMESTAMP,
FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Also ON UPDATE CURRENT_TIMESTAMP part is not relevant for created_at field, but relevant for updated_at
First query:
SELECT
u.id,
u.first_name,
u.last_name,
u.tazkera_id,
cu.relation_type,
CASE csp.`shift`
WHEN '1' THEN 'Morning'
WHEN '2' THEN 'Afternoon'
else 'Neither'
END AS shift
FROM `course_user` as cu
LEFT JOIN `courses` as c ON c.id = cu.`course_id`
LEFT JOIN (
select users.id,
users.first_name,
users.last_name,
users.tazkera_id
FROM `users`
) as u ON u.id = cu.`user_id`
left JOIN `course_schedule_prefs` as csp ON csp.`user_id` = cu.`user_id`
Where cu.relation_type = 1 group by cu.`user_id`;
Second Query:
SELECT
u.id,
u.first_name,
u.last_name,
u.tazkera_id,
cu.relation_type,
CASE csp.`shift`
WHEN '1' THEN 'Morning'
WHEN '2' THEN 'Afternoon'
else 'Neither'
END AS shift
FROM `course_user` as cu
LEFT JOIN `courses` as c ON c.id = cu.`course_id`
LEFT JOIN users as u ON u.id = cu.`user_id`
left JOIN `course_schedule_prefs` as csp ON csp.`user_id` = cu.`user_id`
Where cu.relation_type = 1 group by cu.`user_id`;
Tables :
users:
CREATE TABLE `users` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`first_name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`last_name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`email` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`password` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`is_password_reset` int(11) NOT NULL DEFAULT '0',
`login_ip` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`login_date` datetime DEFAULT NULL,
`last_login_ip` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`last_login_date` datetime DEFAULT NULL,
`is_email_address_verified` int(11) NOT NULL DEFAULT '0',
`failed_login_attempts` int(11) DEFAULT NULL,
`last_failed_login_date` datetime DEFAULT NULL,
`tazkera_id` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`province_code` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`district_code` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`village` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`home_address` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`promote_unique_user_id` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`remember_token` varchar(100) COLLATE utf8_unicode_ci DEFAULT NULL,
`forgot_token` varchar(100) COLLATE utf8_unicode_ci DEFAULT NULL,
`email_confirm_token` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`district_other` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`father_name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`training_provider_id` int(10) unsigned DEFAULT NULL,
`is_profile_completed` int(11) DEFAULT NULL,
`active` int(11) DEFAULT '1',
`picture` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`small_picture` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`last_poll` bigint(20) DEFAULT NULL,
`last_password_reset` date DEFAULT NULL,
`presence_status` int(11) DEFAULT NULL,
`auto_presence` int(11) NOT NULL DEFAULT '0',
`last_activity` timestamp NULL DEFAULT NULL,
`trash` tinyint(4) NOT NULL DEFAULT '0',
`login_approval` tinyint(4) NOT NULL DEFAULT '0',
`lang` varchar(2) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'en',
`cover` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`small_cover` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`forum_reputation` int(11) NOT NULL DEFAULT '0',
`forum_suspension_date` date DEFAULT NULL,
`forum_status` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `users_email_unique` (`email`),
KEY `users_training_provider_id_foreign` (`training_provider_id`),
CONSTRAINT `users_training_provider_id_foreign` FOREIGN KEY (`training_provider_id`) REFERENCES `training_providers` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=1000038 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
course_users:
CREATE TABLE `course_user` (
`course_id` int(10) unsigned DEFAULT NULL,
`user_id` int(10) unsigned DEFAULT NULL,
`relation_type` int(11) DEFAULT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
KEY `course_user_course_id_foreign` (`course_id`),
KEY `course_user_user_id_foreign` (`user_id`),
CONSTRAINT `course_user_course_id_foreign` FOREIGN KEY (`course_id`) REFERENCES `courses` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `course_user_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
courses;
CREATE TABLE `courses` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`curriculum_id` int(10) unsigned DEFAULT NULL,
`training_center_id` int(10) unsigned DEFAULT NULL,
`training_coordinator_id` int(10) unsigned DEFAULT NULL,
`focal_point_id` int(10) unsigned DEFAULT NULL,
`start_date` date DEFAULT NULL,
`end_date` date DEFAULT NULL,
`start_time` time DEFAULT NULL,
`end_time` time DEFAULT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`shift` int(11) DEFAULT NULL,
`stage_id` int(10) unsigned DEFAULT NULL,
`stream_id` int(10) unsigned DEFAULT NULL,
`unit_id` int(10) unsigned DEFAULT NULL,
`master_trainer_id` int(10) unsigned DEFAULT NULL,
`status` int(11) DEFAULT NULL,
`pre_test_generated` int(11) NOT NULL DEFAULT '0',
`post_test_generated` int(11) NOT NULL DEFAULT '0',
`conduct_days` int(11) DEFAULT NULL,
`no` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`evaluation_available` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `courses_curriculum_id_foreign` (`curriculum_id`),
KEY `courses_training_coordinator_id_foreign` (`training_coordinator_id`),
KEY `courses_focal_point_id_foreign` (`focal_point_id`),
KEY `courses_stage_id_foreign` (`stage_id`),
KEY `courses_stream_id_foreign` (`stream_id`),
KEY `courses_unit_id_foreign` (`unit_id`),
KEY `courses_master_trainer_id_foreign` (`master_trainer_id`),
KEY `courses_training_center_id_foreign` (`training_center_id`),
CONSTRAINT `courses_curriculum_id_foreign` FOREIGN KEY (`curriculum_id`) REFERENCES `curriculums` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `courses_focal_point_id_foreign` FOREIGN KEY (`focal_point_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `courses_master_trainer_id_foreign` FOREIGN KEY (`master_trainer_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `courses_stage_id_foreign` FOREIGN KEY (`stage_id`) REFERENCES `stages` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `courses_stream_id_foreign` FOREIGN KEY (`stream_id`) REFERENCES `streams` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `courses_training_center_id_foreign` FOREIGN KEY (`training_center_id`) REFERENCES `training_centers` (`id`),
CONSTRAINT `courses_training_coordinator_id_foreign` FOREIGN KEY (`training_coordinator_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `courses_unit_id_foreign` FOREIGN KEY (`unit_id`) REFERENCES `units` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=139 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
course_schedule_prefs;
CREATE TABLE `course_schedule_prefs` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`cunduct_days` int(11) DEFAULT NULL,
`training_centers` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`shift` int(11) NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`user_id` int(10) unsigned DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `course_schedule_prefs_user_id_foreign` (`user_id`),
CONSTRAINT `course_schedule_prefs_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
My question is , which one of this query is good in term of performance and accuracy. Why ?
first query: I join directly with table; select all columns of table.
Second query: I used subquery inside of join; select only those element which I need it.
Note : My main question is about users table which is in join
There are too many possibilities here. There is no simple, 'straight', answer.
With LEFT JOIN (instead of JOIN), the Optimizer cannot start with the subquery, which it would usually like to do.
If there is a WHERE clause and it is useful for filtering rows, the Optimizer would like to start with the table that is filtered the most. Your WHERE clause smells like a flag, which is usually not very useful.
If a subquery has a GROUP BY or LIMIT, then it may significantly shrink the number of rows to work with. (Not in your case.) This might make the subquery approach better.
If cu has INDEX(relation_type, user_id), the Optimizer may decide that handling all of the WHERE and GROUP BY leads to the best bet, thereby starting with cu as the 'first' table.
In old versions of MySQL, subqueries in JOIN ( SELECT ... ) had no way of getting an index, thereby leading to inefficient table scans of that tmp table. In new versions (starting with 5.6, I think), the Optimizer takes the extra step (which costs something) to generate the optimal index ((id) in this case) after creating the tmp table and before JOINing it.
More
2 more table definitions needed.
Do you have the indexes I suggested?
InnoDB really needs a PRIMARY KEY - See many:many for advice on course_user.
I need help with a query running slow when using group by:
SELECT `customers`.`id`
,`customers`.`firstname`
,`customers`.`lastname`
,`customers`.`address`
,`customers`.`address_co`
,`customers`.`country`
,`customers`.`zipcode`
,`customers`.`city`
,`customers`.`phone`
,`customers`.`mobilephone`
,`customers`.`ssn`
,`users`.`email`
,`customer_lists`.`name` AS `customerList`
,COUNT( transactions.id ) AS transactions_count
,SUM( transactions.sum_incl ) AS sum_incl
,SUM( transactions.sum_excl ) AS sum_excl
,`customers`.`created_at`
FROM `customers`
INNER JOIN `users`
ON `customers`.`user_id` = `users`.`id`
LEFT JOIN `transactions`
ON `customers`.`id` = `transactions`.`customer_id`
INNER JOIN `customer_lists`
ON `customers`.`customer_list_id` = `customer_lists`.`id`
WHERE `customer_lists`.`club_id` = '1'
GROUP BY `customers`.`id`
ORDER BY `customers`.`created_at` DESC
When I run a EXPLAIN it says Using temporary; Using filesort.
**id** **select_type** **table** **type** **possible_keys** **key** **key_len** **ref** **rows** **Extra**
1 SIMPLE customer_lists ref PRIMARY,club_id_index club_id_index 8 const 1 Using temporary; Using filesort
1 SIMPLE customers ref customers_user_id_foreign,customers_customer_list_... customers_customer_list_id_index 8 kund_workbox_nu.customer_lists.id 867
1 SIMPLE users eq_ref PRIMARY PRIMARY 8 kund_workbox_nu.customers.user_id 1
1 SIMPLE transactions ref customer_id_index customer_id_index 8 kund_workbox_nu.customers.id 3108
How do I fix that?
UPDATE
Tables:
Customers
CREATE TABLE `customers` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`user_id` bigint(20) unsigned NOT NULL,
`customer_list_id` bigint(20) unsigned NOT NULL,
`firstname` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`lastname` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`address` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`address_co` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`country` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`zipcode` varchar(10) COLLATE utf8_unicode_ci NOT NULL,
`city` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`phone` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
`mobilephone` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
`ssn` varchar(15) COLLATE utf8_unicode_ci NOT NULL,
`last_login` datetime NOT NULL,
`added_information` tinyint(1) NOT NULL DEFAULT '0',
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`),
KEY `customers_user_id_foreign` (`user_id`),
KEY `customers_customer_list_id_index` (`customer_list_id`),
CONSTRAINT `customers_customer_list_id_foreign` FOREIGN KEY (`customer_list_id`) REFERENCES `customer_lists` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `customers_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=29739 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Transactions
CREATE TABLE `transactions` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`transaction_type_id` bigint(20) unsigned NOT NULL,
`customer_id` bigint(20) unsigned NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`sum_incl` decimal(15,4) NOT NULL,
`sum_excl` decimal(15,4) NOT NULL,
PRIMARY KEY (`id`),
KEY `transactions_customer_id_foreign` (`customer_id`),
KEY `transactions_transaction_type_id_foreign` (`transaction_type_id`),
CONSTRAINT `transactions_customer_id_foreign` FOREIGN KEY (`customer_id`) REFERENCES `customers` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `transactions_transaction_type_id_foreign` FOREIGN KEY (`transaction_type_id`) REFERENCES `transaction_types` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=580116 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Customer Lists
CREATE TABLE `customer_lists` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`club_id` bigint(20) unsigned NOT NULL,
`name` varchar(90) COLLATE utf8_unicode_ci NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`),
KEY `customer_lists_club_id_foreign` (`club_id`),
CONSTRAINT `customer_lists_club_id_foreign` FOREIGN KEY (`club_id`) REFERENCES `clubs` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Perhaps try a single table grouping on transactions as a derived table?
SELECT
`customers`.`id`
, `customers`.`firstname`
, `customers`.`lastname`
, `customers`.`address`
, `customers`.`address_co`
, `customers`.`country`
, `customers`.`zipcode`
, `customers`.`city`
, `customers`.`phone`
, `customers`.`mobilephone`
, `customers`.`ssn`
, `users`.`email`
, `customer_lists`.`name` AS `customerList`
, `trans`.transactions_count
, `trans`.sum_incl
, `trans`.sum_excl
, `customers`.`created_at`
FROM `customers`
INNER JOIN `users` ON `customers`.`user_id` = `users`.`id`
INNER JOIN `customer_lists` ON `customers`.`customer_list_id` = `customer_lists`.`id`
LEFT JOIN (
SELECT
`transactions`.`customer_id`
, COUNT(transactions.id) AS transactions_count
, SUM(transactions.sum_incl) AS sum_incl
, SUM(transactions.sum_excl) AS sum_excl
FROM `transactions`
GROUP BY `transactions`.`customer_id`
) `trans` ON `customers`.`id` = `trans`.`customer_id`
WHERE `customer_lists`.`club_id` = '1'
ORDER BY `customers`.`created_at` DESC
A where clause in that subquery may also help.
Have you tried to create indexes on all the JOIN columns, i.e. customers.user_id, users.id, transactions.customer_id, ... ?
I've read many somewhat similar questions here and tried everything I can think of, without success. I think I've found the question based on a single table, or without the need for getting a distinct column, but not my situation exactly.
I want to get distinct ticker_symbol and corresponding ticker_name and latest ticker_quote based on these tables:
CREATE TABLE `tickers` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`ticker_symbol` varchar(6) COLLATE utf8_unicode_ci NOT NULL,
`ticker_name` varchar(128) COLLATE utf8_unicode_ci NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
CREATE TABLE `ticker_quotes` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`ticker_symbol` varchar(6) COLLATE utf8_unicode_ci NOT NULL,
`ticker_quote` float(8,2) NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=111 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
Try
SELECT q.ticker_symbol, t.ticker_name, q.ticker_quote
FROM (SELECT ticker_symbol, MAX(created_at) created_at
FROM ticker_quotes
GROUP BY ticker_symbol) m JOIN
ticker_quotes q ON m.ticker_symbol = q.ticker_symbol
AND m.created_at = q.created_at JOIN
tickers t ON q.ticker_symbol = t.ticker_symbol
SQLFiddle
I am a beginner in MySQL and trying to create a join query in MySQL.
My first SQL query is as below which displays the 2 columns votes and post
SELECT votes, post
FROM `wp_votes` where votes!=''
GROUP BY votes,post asc LIMIT 0 , 30
**Second table is where the posts are **
SELECT *
FROM `wp_posts`
LIMIT 0 , 30
What i wanna do is create a join so that it display all records from wp_posts table WHERE wp_post.ID=wp_votes.post, Also have to check if wp_votes.votes!=''
I tried the following but i am stuck on it
SELECT * FROM wp_posts join wp_votes ON wp_posts.ID =wp_votes.post
Table Structure below
CREATE TABLE IF NOT EXISTS `wp_posts` (
`ID` bigint(20) unsigned NOT NULL auto_increment,
`post_author` bigint(20) unsigned NOT NULL default '0',
`post_date` datetime NOT NULL default '0000-00-00 00:00:00',
`post_date_gmt` datetime NOT NULL default '0000-00-00 00:00:00',
`post_content` longtext NOT NULL,
`post_title` text NOT NULL,
`post_excerpt` text NOT NULL,
`post_status` varchar(20) NOT NULL default 'publish',
`comment_status` varchar(20) NOT NULL default 'open',
`ping_status` varchar(20) NOT NULL default 'open',
`post_password` varchar(20) NOT NULL default '',
`post_name` varchar(200) NOT NULL default '',
`to_ping` text NOT NULL,
`pinged` text NOT NULL,
`post_modified` datetime NOT NULL default '0000-00-00 00:00:00',
`post_modified_gmt` datetime NOT NULL default '0000-00-00 00:00:00',
`post_content_filtered` longtext NOT NULL,
`post_parent` bigint(20) unsigned NOT NULL default '0',
`guid` varchar(255) NOT NULL default '',
`menu_order` int(11) NOT NULL default '0',
`post_type` varchar(20) NOT NULL default 'post',
`post_mime_type` varchar(100) NOT NULL default '',
`comment_count` bigint(20) NOT NULL default '0',
PRIMARY KEY (`ID`),
KEY `post_name` (`post_name`),
KEY `type_status_date` (`post_type`,`post_status`,`post_date`,`ID`),
KEY `post_parent` (`post_parent`),
KEY `post_author` (`post_author`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=4570 ;
--
-- Table structure for table `wp_votes`
--
CREATE TABLE IF NOT EXISTS `wp_votes` (
`ID` int(11) NOT NULL auto_increment,
`post` int(11) NOT NULL,
`votes` text NOT NULL,
`guests` text NOT NULL,
`usersinks` text NOT NULL,
`guestsinks` text NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1052 ;
SELECT a.votes, a.post,
b.*
FROM wp_votes a
INNER JOIN wp_Post b
ON a.post = b.ID
WHERE a.votes <> ''
To further gain more knowledge about joins, kindly visit the link below:
Visual Representation of SQL Joins