SELECT TOP 1 * FROM Customers;
This gives me all customer details of first row
( customerid, customer name etc..,)
SELECT TOP 1 1 FROM Customers;
I got o/p as
Expr1000
------------
1
But I genuinely don't understand above output, and I searched for it but couldn't get the clear understanding of it.
If your first query * mean show all fields
But:
SELECT TOP 1 1 FROM Customers;
is equal to:
SELECT TOP 1
1 as myConstantField FROM Customers;
So you create a single constant field and you will get 1 for every row in Customers, but TOP 1 will filter to only the first one
The second "1" is not considered as a column, it's just a constant. So with this query, you ask to write down one (TOP 1) row with one column with the constant "1". Same thing will happen if you write something like this :
SELECT TOP 1 'Hey you', 1 as valueone ,2 ,3, customerid
FROM Customers ;
You'll have one row with the values 'Hey you' , '1' in column "valueone", '2', '3' then your customerid from the first row
When you
SELECT 1
it will show just one row of 1. When you
SELECT 1 FROM Customers
it will give you the number of rows that there in Customers. So when you
SELECT TOP 1 1 FROM Customers
it will give you only the first row of 1 as if you did
SELECT TOP 1 * FROM Customers
Related
Would it be possible to add more rows base on Keyword string in SQL ?
table A
PID PromotionName
1 OUT_EC_D10_V500K_FamilyCare_PROCO
2 OUT_EC_D5_V50K_Lunchbox_PROCO
3 OUT_EC_D5_V50K_PROCO
table B
promotion_code itm_name quantity
Lunchbox Item name 1 1
FamilyCare Item name 2 1
FamilyCare Item name 3 1
BUY1FREE6 Item name 4 1
HiSummer Item name 5 1
FamilyCare Item name 6 1
Example:
SELECT * FROM A where pid = '1';
Output of the SQL should be -
PID PromotionName Itm_name quantity
1 OUT_EC_D10_V500K_FamilyCare_PROCO
2 FamilyCare Item name 2 1
3 FamilyCare Item name 3 1
4 FamilyCare Item name 6 1
How to find string with keyword 'FamilyCare' in PromotionName of table A base on promotion_code of table B? If it exist it will add more rows in output
Any help with the SQL?
Here is how you can achieve this:
SELECT PID,PromotionName, '' as Itm_name, NULL as quantity
FROM A
WHERE pid = '1'
UNION
SELECT PID, PROMOTION_NAME, Itm_name, quantity
FROM
(SELECT * FROM A inner join B on a.promotionName LIKE '%'||b.promotion_name||'%')
WHERE pid='1'
You have to update your pid in both the places (before and after UNION).
Notice that tables were joined using LIKE operator with % before and after the word. Hence this joins if a part of a string is present in another column.
db<>fiddle link here
An option would be starting to construct a subquery factoring along with joining tables through a.promotionName LIKE '%'||b.promotion_code||'%' condition while filtering by b.promotion_code = 'FamilyCare', then add another query to combine the result sets by UNION ALL, and then enumerate with an id column by ROW_NUMBER() analytic function such as
WITH ab AS
(
SELECT a.*, b.*
FROM a
JOIN b
ON a.promotionName LIKE '%'||b.promotion_code||'%'
WHERE b.promotion_code = 'FamilyCare'
), ab2 AS
(
SELECT promotion_code, itm_name, quantity
FROM ab
UNION ALL
SELECT DISTINCT promotionName, NULL, NULL
FROM ab
)
SELECT ROW_NUMBER() OVER (ORDER BY itm_name NULLS FIRST) AS pid,
a.*
FROM ab2 a
if there's mismatch for the topmost query, then no row will be returned. eg. that query will check for the existence for the literal you provide
Demo
After many attempts I have failed at this and hoping someone can help. The query returns every entry a user makes when items are made in the factory against and order number. For example
Order Number Entry type Quantity
3000 1 1000
3000 1 500
3000 2 300
3000 2 100
4000 2 1000
5000 1 1000
What I want to the query do is to return filter the results like this
If the order number has an entry type 1 and 2 return the row which is type 1 only
otherwise just return row whatever the type is for that order number.
So the above would end up:
Order Number Entry type Quantity
3000 1 1000
3000 1 500
4000 2 1000
5000 1 1000
Currently my query (DB2, in very basic terms looks like this ) and was correct until a change request came through!
Select * from bookings where type=1 or type=2
thanks!
select * from bookings
left outer join (
select order_number,
max(case when type=1 then 1 else 0 end) +
max(case when type=2 then 1 else 0 end) as type_1_and_2
from bookings
group by order_number
) has_1_and_2 on
type_1_and_2 = 2
has_1_and_2.order_number = bookings.order_number
where
bookings.type = 1 or
has_1_and_2.order_number is null
Find all the orders that have both type 1 and type 2, and then join it.
If the row matched the join, only return it if it is type 1
If the row did not match the join (has_type_2.order_number is null) return it no matter what the type is.
A "common table expression" [CTE] can often simplify your logic. You can think of it as a way to break a complex problem into conceptual steps. In the example below, you can think of g as the name of the result set of the CTE, which will then be joined to
WITH g as
( SELECT order_number, min(type) as low_type
FROM bookings
GROUP BY order_number
)
SELECT b.*
FROM g
JOIN bookings b ON g.order_number = b.order_number
AND g.low_type = b.type
The JOIN ON conditions will work so that if both types are present then low_type will be 1, and only that type of record will be chosen. If there is only one type it will be identical to low_type.
This should work fine as long as 1 and 2 are the only types allowed in the bookings table. If not then you can simply add a WHERE clause in the CTE and in the outer SELECT.
In the example table below, I'm trying to figure out a way to sum amount over marks in two situations: the first, when mark 'C' exists within a single id, and the second, when mark 'C' doesn't exist within an id (see id 1 or 2). In the first situation, I want to exclude the amount against mark 'A' within that id (see id 3 in the desired conversion table below). In the second situation, I want to perform no exclusion and take a simple sum of the amounts against the marks.
In other words, for id's containing both mark 'A' and 'C', I want to make the amount against 'A' as zero. For id's that do not contain mark 'C' but contain mark 'A', keep the original amount against mark 'A'.
My desired output is at the bottom. I've considered trying to partition over id or use the EXISTS command, but I'm having trouble conceptualizing the solution. If any of you could take a look and point me in the right direction, it would be greatly appreciated :)
example table:
id mark amount
------------------
1 A 1
2 A 3
2 B 2
3 A 1
3 C 3
desired conversion:
id mark amount
------------------
1 A 1
2 A 3
2 B 2
3 A 0
3 C 3
desired output:
mark sum(amount)
--------------------
A 4
B 2
C 3
You could slightly modify my previous answer and end up with this:
SELECT
mark,
sum(amount) AS sum_amount
FROM atable t
WHERE mark <> 'A'
OR NOT EXISTS (
SELECT *
FROM atable
WHERE id = t.id
AND mark = 'C'
)
GROUP BY
mark
;
There's a live demo at SQL Fiddle.
Try:
select
mark,
sum(amount)
from ( select
id,
mark,
case
when (mark = 'A' and id in (select id from table where mark = 'C')) then 0
else amount
end as amount
from table ) t1
group by mark
I am having data like:
ItemCode Attribute PositionID
ITEM-000032 CHESTSIZE 1
ITEM-000032 JACKETLEN 2
ITEM-000042 CHESTSIZE 1
ITEM-000042 JACKETLEN 2
**ITEM-000049 SLACKWAIST 1**
ITEM-000071 CHESTSIZE 1
ITEM-000071 JACKETLEN 2
ITEM-000074 CHESTSIZE 1
ITEM-000074 JACKETLEN 2
In above data except ITEM-000049 others are having perfect combination. so i want to create a new row for ITEM-000049
As
ITEM-000049 -- 2
to make it perfect.
Kind regards,
Om
Sounds like for each ItemCode, you are expecting 2 records, for 2 different Attributes.
So something like this is what I think you're after. Just run the SELECT part of it first without the INSERT to check it is indeed what you're after.
INSERT YourTable (ItemCode, Attribute, PositionID)
SELECT t.ItemCode, 'SECOND ATTRIBUTE', 2
FROM
(
SELECT ItemCode
FROM YourTable
GROUP BY ItemCode
HAVING COUNT(*) = 1
) t
SELECT student_id, section, count( * ) as total
FROM raw_data r
WHERE response = 1
GROUP BY student_id, section
There are 4 sections on the test, each with a different number of questions. I want to know, for each student, and each section, how many questions they answered correctly (response=1).
However, with this query, if a student gets no questions right in a given section, that row will be completely missing from my result set. How can I make sure that for every student, 4 rows are ALWAYS returned, even if the "total" for a row is 0?
Here's what my result set looks like:
student_id section total
1 DAP--29 3
1 MEA--16 2
1 NNR--13 1 --> missing the 4th section for student #1
2 DAP--29 1
2 MEA--16 4
2 NNR--13 2 --> missing the 4th section for student #2
3 DAP--29 2
3 MEA--16 3
3 NNR--13 3 --> missing the 4th section for student #3
4 DAP--29 5
4 DAP--30 1
4 MEA--16 1
4 NNR--13 2 --> here, all 4 sections show up because student 4 got at least one question right in each section
Thanks for any insight!
UPDATE: I tried
SELECT student_id, section, if(count( * ) is null, 0, count( * )) as total
and that didn't change the results at all. Other ideas?
UPDATE 2: I got it working thanks to the response below:
SELECT student_id, section, SUM(CASE WHEN response = '1' THEN 1 ELSE 0 END ) AS total
FROM raw_data r
WHERE response = 1
GROUP BY student_id, section
SELECT student_id, section, sum(case when response=1 then 1 else 0 end) as total
FROM raw_data_r GROUP BY student_id, section
Note that there's no WHERE condition.
SELECT r.student_id,
r.subject,
sum( r.response ) as total
FROM raw_data r
GROUP BY student_id, subject
if you have a separate table with student information, you can select students from that table and left join the results to the data_raw table:
SELECT si.student_name, rd.student_id, rd.section, rd.count(*) AS total
FROM student_info AS si LEFT JOIN raw_data AS rd USING rd.student_id = si.student_id
This way, it first selects all students, then executes the count command.