I am using UNION to get joined output from 2 rows. A and B, following is the code.
"SELECT `ent_id` as `id`, `owner_id`, `category_id`, `ent_name` as `name`, `ent_details` as `details` FROM `A` WHERE `category_id` = '$cat'
UNION
SELECT `service_id` as `id`, `owner_id`, `category_id`, `service_name` as `name`, `service_details` as `details` FROM `B` WHERE `category_id` = '$cat'
The query works absolutely fine however I now want to know which output is from table A and which from B.
Is there a way to do this? If so how?
Thanks for your time. :)
Add a constant value to each select:
select 'table a' as source_table, ... from A where ...
union all
select 'table b' as source_table, ... from B where ...
Also, union eliminates duplicates between the two sets that form the union which union all doesn't. If there can be no duplicates you should use union all for better performance.
Related
I have a query that goes something like this :
INSERT IGNORE INTO `destination_table` (`id`, `field1`, `field2`, `field3`)
SELECT `id`, `field1`, `field2`, `field3`
FROM `source_table`
WHERE `source_table`.`id` IN (
SELECT DISTINCT `id` FROM `some_table`
UNION DISTICT SELECT DISTINCT `id` FROM `some_other_table`
);
This does not work -- the query hangs indefinitely. The size of the tables is definitely not the problem, all tables have a fairly small number of records ( < 100k records). The query is fine and quite fast if I run it without the UNION :
INSERT IGNORE INTO `destination_table` (`id`, `field1`, `field2`, `field3`)
SELECT `id`, `field1`, `field2`, `field3`
FROM `source_table`
WHERE `source_table`.`id` IN (
SELECT DISTINCT `id` FROM `some_table` -- I tried with `some_other_table` too, same result
);
or
INSERT IGNORE INTO `destination_table` (`id`, `field1`, `field2`, `field3`)
SELECT `id`, `field1`, `field2`, `field3`
FROM `source_table`
both work and are nice and fast (well under a second). So I imagine that the UNION DISTICT SELECT ... is the culprit here, but I don't know why.
What's wrong with that query and why does it hang ?
Using mysql 5.7 is that makes a difference
Your first query seems to have a few typos, but I would suggest using exists logic here:
INSERT IGNORE INTO destination_table (id, field1, field2, field3)
SELECT id, field1, field2, field3
FROM source_table t1
WHERE
EXISTS (SELECT 1 FROM some_table s1 WHERE s1.id = t1.id) OR
EXISTS (SELECT 1 FROM some_other_table s2 WHERE s2.id = t1.id);
The possible advantage of using exists in this way is that MySQL can stop searching as soon as it finds the first matching id in either of the subqueries on the two tables. You may find that adding an index on the id columns in the two other would help (assuming that id be not already indexed):
CREATE INDEX some_idx_1 ON some_table (id);
CREATE INDEX some_idx_2 ON some_other_table (id);
This should speed up the lookup of the id in the two dependent tables.
You could work around the problem by rephrasing the query:
INSERT IGNORE INTO `destination_table` (`id`, `field1`, `field2`, `field3`)
SELECT `id`, `field1`, `field2`, `field3`
FROM `source_table`
WHERE `source_table`.`id` IN (
SELECT DISTINCT `id` FROM `some_table`
)
OR `source_table`.`id` IN (
SELECT DISTINCT `id` FROM `some_other_table`
);
I am new to SQL, so I am not too sure how to go about this query that I have to do ...
I have multiple tables which all have 2 columns that i want to take (date_added and path).
So I did an Union select ("date_added" and "path") for each table. So I now have a table with all rows from all the tables I want:
SELECT `date_added`, `path` FROM `art_1` UNION SELECT `date_added`, `path` FROM `art_5484`
This works fine, but now I need to get the row with the lowest date ( I use min function). So I want to do select on the table that I got from my last query so I do:
SELECT `path`
FROM cross_join = (SELECT `date_added`, `path` FROM `art_1` UNION SELECT `date_added`, `path` FROM `art_5484`)
WHERE `date_added` = MIN(`date_added`)
But this doesn't work; I am guessing it's a syntax error, but i can't see where ...
if anybody could help me out, that would be great !
One way to get the minimum date is to use order by and limit:
SELECT `path`
FROM (SELECT `date_added`, `path` FROM `art_1` UNION ALL
SELECT `date_added`, `path` FROM `art_5484`
) a
ORDER BY date_added DESC
LIMIT 1;
Note: this returns only one value, even if when there are duplicates. Also, I changed the UNION to UNION ALL. You should use UNION ALL by default, because UNION incurs the overhead of removing duplicates.
I've trying to concatenate the values of 2 GROUP_CONCAT( columns ) from a single table that's been joined twice, then get the unique items from the list.
I can do all this outside of my query but if possible it would be nice to just pull the data from the DB with a JOIN and some fancy string manipulation.
Simply put, I want to produce 1,2,3,4 from selecting 1,2,3 and 1,3,4. The 1,2,3 adn 1,3,4 are the results of the GROUP_CONCAT on the twice joined table. I can get this far:
SELECT CONCAT_WS(
",",
"1,2,3",
"1,3,4"
)
Which outputs 1,2,3,1,3,4
I'd like to be able to do something like:
-- NOTE TO SKIM READERS: THIS QUERY WILL NOT WORK
SELECT
SORT_LIST(
DISTINCT
CONCAT_WS(
",",
"1,2,3",
"1,3,4"
)
)
-- NOTE TO SKIM READERS: THIS QUERY WILL NOT WORK
But I can't find anything like that in MySQL.
The 1,2,3 and 1,3,4 have already been produced with GROUP_CONCAT( DISTINCTcol)
As stated in my comment I worked out a way to achieve distinct concatenated lists of strings using a sub query:
DROP TABLE IF EXISTS `test1234`;
CREATE TABLE `test1234` (
`val` int(1),
`type` varchar(1)
);
INSERT INTO `test1234` VALUES
( 1, 'a' ),
( 2, 'a' ),
( 3, 'a' ),
( 1, 'b' ),
( 3, 'b' ),
( 4, 'b' );
SELECT GROUP_CONCAT( `val` ) AS `vals`
FROM (
(
SELECT `val` FROM `test1234` WHERE `type` = 'a'
) UNION DISTINCT (
SELECT `val` FROM `test1234` WHERE `type` = 'b'
)
) AS `test`;
DROP TABLE IF EXISTS `test1234`;
This selected 1,2,3,4
I have a table like this:
Fiddle: http://sqlfiddle.com/#!2/44d9e/14
CREATE TABLE IF NOT EXISTS `mytable` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`user_id` int(20) NOT NULL,
`money_earned` int(20) NOT NULL,
PRIMARY KEY (`id`)
) ;
INSERT INTO mytable (user_id,money_earned) VALUES ("111","10");
INSERT INTO mytable (user_id,money_earned) VALUES ("111","6");
INSERT INTO mytable (user_id,money_earned) VALUES ("111","40");
INSERT INTO mytable (user_id,money_earned) VALUES ("222","45");
INSERT INTO mytable (user_id,money_earned) VALUES ("222","1");
INSERT INTO mytable (user_id,money_earned) VALUES ("333","5");
INSERT INTO mytable (user_id,money_earned) VALUES ("333","19");
I need to know table has how many rows, how many different users, and how many times each user has earned.
I need this result:
TOTAL_ROWS: 7
TOTAL_INDIVIDUAL_USERS: 3
USER_ID USER_TIMES
111 3
222 2
333 2
Is your problem that you want the total as well? If so, then you can get this using rollup:
SELECT coalesce(cast(user_id as char(20)), 'TOTAL USER_TIMES'),
COUNT(*) as times
FROM mytable
GROUP BY user_id with rollup;
You can get the user counts in a separate column with this trick:
SELECT coalesce(cast(user_id as char(20)), 'TOTAL USER_TIMES'),
COUNT(*) as times, count(distinct user_id) as UserCount
FROM mytable
GROUP BY user_id with rollup;
You realize that a SQL query just returns a table of values. You are asking for very specific formatting, which is typically done better at the application level. That said, you can get close to what you want with something like this:
select user, times
from ((SELECT 3 as ord, cast(user_id as char(20)) as user, COUNT(*) as times
FROM mytable
GROUP BY user_id
)
union all
(select 1, 'Total User Count', count(*)
from mytable
)
union all
(select 2, 'Total Users', count(distinct user_id)
from mytable
)
) t
order by ord;
I think this could be a typo anyway your are trying to sum your COUNT() times, simply replace with money_earned
SELECT user_id,
COUNT(*) AS 'times',
SUM(money_earned) AS 'sum_money'
FROM mytable GROUP BY user_id;
SQL Fiddle
I want to order one mysql table by two strtotime timestamps from two different columns. I've got the following mysql command:
SELECT * FROM (
(SELECT '1' AS `table`, `vid_req_timestamp` AS `timestamp`, `title` FROM `movies` WHERE `vid_req` = '1')
UNION
(SELECT '2' AS `table`, `ost_req_timestamp` AS `timestamp`, `title` FROM `movies` WHERE `ost_req` = '1')
)
ORDER BY `timestamp` DESC
This gives me an error:
#1248 - Every derived table must have its own alias
I want to combine vid_req_timestamp and ost_req_timestamp and make those descending. And it's important to know where the timestamp came from (somehow).
In this case, the derived table that requires an alias is the one that you are SELECTing * from.
Indentation helps make that clearer.
SELECT * FROM
(
(SELECT '1' AS `table`, `vid_req_timestamp` AS `timestamp`, `title` FROM `movies` WHERE `vid_req` = '1')
UNION
(SELECT '2' AS `table`, `ost_req_timestamp` AS `timestamp`, `title` FROM `movies` WHERE `ost_req` = '1')
) AS `some_table_name_lol_this_is_an_alias`
ORDER BY `timestamp` DESC