I have a column Date with the same name in four tables Products, Customers, Shops, World in mysql. what i want to do is that i want to find the greatest date in the DATE COLUMN of all four tables. I don't want the greatest date of every table but the greatest one in all four tables. I hope you are understanding. Please help me
The most efficient way I can think of would be using the greatest function:
select greatest(
(select max(date) from products),
(select max(date) from customers),
(select max(date) from shops),
(select max(date) from world)
) greatest_date
SQLFiddle demo
This might work:
SELECT MAX(Date) as Max_Date
FROM (
SELECT Date FROM Products
UNION
SELECT Date FROM Customers
UNION
SELECT Date FROM Shops
UNION
SELECT Date FROM World
) AS P;
Related
I’m trying to retrieve the number of unique users that have made a purchase in a monthly basis. This sounds simple but the problem here is that we have three type of products and the purchases of these products are on different tables in which the only common key is the user_id, so in order to find out unique users I have to query the three tables separately, union the results and execute a count distinct.
Here’s an example of what I’m doing right now:
SELECT
month,
count(distinct user_id) as users
FROM
(
SELECT
DATE_FORMAT(purchase_date,’%Y-%m) as month,
user_id
FROM purchases_a
UNION
SELECT
DATE_FORMAT(purchase_date,’%Y-%m) as month,
user_id
FROM purchases_b
UNION
SELECT
DATE_FORMAT(purchase_date,’%Y-%m) as month,
user_id
FROM purchases_c
)
GROUP BY 1
Is this the only way to go? This query takes forever. Thanks!
One method is to use union all in a subquery and then aggregate:
select DATE_FORMAT(purchase_date, '%Y-%m') as month,
count(distinct user_id)
from ((select user_id, purchase_date from purchases_a) union all
(select user_id, purchase_date from purchases_b) union all
(select user_id, purchase_date from purchases_c)
) p
group by month
I've got a database which has the table updates which contains: product_name, environment, version, date, task.
I need to select only the newest of all and all at one date in time.
Something following will give you all records from max date of each product
select * from table allDates JOIN
( select max(date) maxdate, product from table group by product) maxDates
allDates.Date= maxDates.maxdate and allDates.product= maxDates.product
for all products of latest date
select * from table where date =
( select max(date) maxdate from table)
the newest of all
Anil had a good idea with
SELECT * FROM table ORDER BY date DESC LIMIT 1;
all at one date in time
SELECT * FROM table WHERE DATE(date) = '2017-11-06'
or if your date contains more than just year, month and day
SELECT * FROM table WHERE date LIKE '2017-11-06%'
first ,i need to get the sum of TotalPrice of sport's and music's departments from the first 3 months of 2016,second, i need to get the result of what i wrote before dividing to sum of all TotalPrice at the year of 2016 from all departments, and third- i need to get the first result dividing to sum of all Total price from all over the years.
all this at the same query!
thanks!
the table called Sales and the attributes are: S_id, date, department, totalPrice.
THIS IS MY CHRY :
Select sum(TotalPrice) as sportMusic, sportMusic/sum(TotalPrice)
From Sales
Where (Department="MUSIC" OR Department="SPORT") and
DATE BETWEEN "2016/01/01" AND "2016/03/31"
You can use your query and two more queries as subqueries (also called "derived tables") in your from clause. Cross join the three result rows and use the totals in your select clause. Something along the lines of:
select
ms_2016_q1.total as ms_2016_q1_total,
ms_2016_q1.total / all_2016.total as rate_2016,
ms_2016_q1.total / all_years.total as rate_all
from
(
select sum(totalprice) as total
from sales
where department in ('MUSIC', 'SPORT')
and date between date '2016-01-01' and date '2016-03-31'
) ms_2016_q1
cross join
(
select sum(totalprice) as total
from sales
where date between date '2016-01-01' and date '2016-12-31'
) all_2016
cross join
(
select sum(totalprice) as total
from sales
) all_years;
I have these two tables
The first one is expenses table and the second one is expensename
Exp_Type(first table) is the Expense name(second table) as 2 is Food
I am trying to group expense according to expense type and get data between certain dates.
This is what i have tried, but it wont work.
select
(select
(select name from EXPENSENAME where id=EXP_TYPE)as ExpenseType,
sum(PRICE) as cost
from EXPENSES WHERE USERID=1 GROUP BY EXPENSES.EXP_TYPE),
[date]
from EXPENSES where [date] BETWEEN '10-09-2015' and '10-18-2015 23:59:59'
And
select
(select name from EXPENSENAME where id=EXP_TYPE)as ExpenseType,
sum(PRICE) as cost,
date
from EXPENSES WHERE USERID=1 and DATE BETWEEN '01/10/2015' and '29/10/2015' GROUP BY EXPENSES.EXP_TYPE
With out date, i am getting result by this query but i need the same data between certain dates,please help
select
(select name from EXPENSENAME where id=EXP_TYPE)as ExpenseType,
sum(PRICE) as cost
from EXPENSES WHERE USERID=1 GROUP BY EXPENSES.EXP_TYPE
you want to join the tables together
SELECT en.name as ExpenseType, SUM(e.price) as cost
FROM expenses e
JOIN expensename en ON en.id = e.exp_type
WHERE e.date BETWEEN '10-09-2015' and '10-18-2015'
GROUP BY en.name
this should give you the cost per name
the current query you have is TERRIBLE... and this is why
SELECT (SELECT ... FROM ... WHERE ... ) as ...
this is creating a correlated subquery which is executing once for every row of the parent select. meaning if you have a table with 4 rows in it (SELECT ... FROM ... WHERE ... ) will execute 4 times scanning 16 rows (assuming its from the same table) in general that is a really really bad way to get data... if you have a million rows... well do the math, its a bad idea
I have "users" table with fields
user_name, user_id
I have data tables like
data_table_2012_10
data_table_2012_11
data_table_2012_12
data_table_2013_01
data_table_2013_02
each table contains the following fields
user_id, type ('ALARM', 'EMERGENCY', 'ALIVE', 'DEAD'), date_time
There will be millions of records in each table.
I have to select the count of type from the data_tables within the time frame given by the user, as well as have to get the corresponding name of the user with the help of user_id.
Can some one help me out with the best solution.
Try this query where DATE1 and DATE2 is your date range. You should union all tables in the inner query. Also you can try to make a query dynamically to include in the inner query only those tables that are in a date range you use:
select t.user_id,t.type, MAX(users.user_name), SUM(t.cnt)
from
(
select user_id,type,count(*) cnt
from data_table_2012_10 where date_time between DATE1 and DATE2
group by user_id,type
union all
select user_id,type,count(*) cnt
from data_table_2012_11 where date_time between DATE1 and DATE2
group by user_id,type
union all
.........................................
union all
select user_id,type,count(*) cnt
from data_table_2013_02 where date_time between DATE1 and DATE2
group by user_id,type
) t
left join users on (t.user_id=users.user_id)
group by t.user_id,t.type
Remember not to use UNION, but UNION ALL as UNION will return only merge similar rows into one and that may cause problem