i have 2 queries, where in one table the amount is shown for cars such as
Amount_Table Cars
800 Car A
900 Car B
2100 Car C
Second Table shows discount respectively for Car A, B & C.
Discount_table
40
10
80
I wish to have a final query where in the Amount-Discount values are displayed
The amount table has one query made and discount table has another query. hence i wish to do
(amount-query) - (discount query)
I did
Select ( (amount-query) - (discount-query))
but that threw error of
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.
Please help!
try something like this:
Select AmountTable.Amount-isnull(DiscountTable.Discount, 0)
from AmountTable left join
on AmountTable.Car = DiscountTable.Car
You cannot "subtract" queries. You have to do a join between tables (or subqueries), and make expressions using columns' names.
You need to join:
SELECT *
,cars_table.amount - discounts_table.discount
FROM cars_table
INNER JOIN discounts_table
ON cars.some_key = discounts_table.some_key
Related
I have a Microsoft access query I'm trying to set up but have hit a snag. I'd describe this as a select query that has a relationship of 1:3.
I have two tables (A & B), table B has one field (a new part number) that I need to compare against three fields in table A (old/new part numbers). I want to do a select query so I can export as a CSV. In this case I need to match 2ABCD so I get a row with the updated price of $5.
The basic format I'm looking at is this.
From table B, I want to check if UPC4 matches UPC1, UPC2 or UPC3 in table A - matching for the value "2ABCD" in this example. Ideally I want to do this in one query. Thoughts?
TABLE A
UPC1
UPC2
UPC3
Price
ABCD
1ABCD
2ABCD
$4
TABLE B
UPC4
Price
2ABCD
$5
END RESULT SELECT QUERY
UPC1
UPC2
UPC3
UPC4
Price
ABCD
1ABCD
2ABCD
2ABCD
$5
Access supports joins https://learn.microsoft.com/de-de/office/vba/access/concepts/structured-query-language/perform-joins-using-access-sql
So you can combine both tables
SELECT
TableA.UPC1,TableA.UPC2,TableA.UPC3,
TableB.UPC4,TableB.Price
FROM
TableA INNER JOIN TableB ON TableA.UPC1 = TableB.UPC4
OR TableA.UPC2 = TableB.UPC4
OR TableA.UPC3 = TableB.UPC4
I'm just getting started with sql and have the objective to transform this:
select X.persnr
from Pruefung X
where X.persnr in (
select Y.persnr
from pruefung Y
where X.matrikelnr <> Y.matrikelnr)
output:
into the same output but using a form of join. I tried it the way below but I can't seem to get "rid" of the cartesian product as far as i can see. Or maybe i misunderstood the above statement what it should actually do. For me the above says "for each unique matrikelnr display all corresponding persnr".
select X.persnr
from Pruefung X
join pruefung y on x.persnr=y.persnr
where x.matrikelnr<>y.matrikelnr
output: A long list (I don't want to fill the entire question with it) - i am guessing the cartesian product from the join
This is the relation I am using.
Edit: Distinct (unless i am using it in the wrong place) won't work because then persnr is only displayed once, thats not the objective though.
Your initial query actually does:
select persnr from Pruefung if the same persnr exists for a a diferent matrikelnr.
"for each unique matrikelnr display all corresponding persnr"
This is achieved using aggregation:
Depending on the DBMS you are using you could use something like (SQL Server uses STRING_AGG, but MySQL uses GROUP_CONCAT)
SELECT matrikelnr,STRING_AGG(matrikelnr,',')
GROUP BY matrikelnr
You cannot easily achieve what you got from a correlated query (your first attempt) by using a join.
Edit:
A join does not result in a "Cartesian product" expect from when there is no join condition (CROSS JOIN).
A join matches two sets based on a join condition. The reason why you get more entries is that the join looks at the join key (PERSNR) and does its matching.
For example for 101 you have 3 entries. That means you will get 3x3 reults.
You then filter out the results for the cases where X.matrikelnr <> Y.matrikelnr If we assume matrikelnr is unique that would mean the row matched with itself. so you will lose 3 results ending up with 3x3 - 3 = 6.
If you want to achieve something in SQL you must first define what you are expecting to use and then use the appropiate tools (in this case correlated queries not joins)
You can write your 1st query with EXISTS instead of IN like:
select X.persnr
from Pruefung X
where exists (
select 1
from pruefung Y
where X.persnr = Y.persnr and X.matrikelnr <> Y.matrikelnr
)
This way it's obvious that this query means:
return all the persnrs of the table for which there exists another
row with the same persnr but different matrikelnr
For your sample data the result is all the persnrs of the table.
Your 2nd query though, does something different.
It links every row of the table with all the rows of the same table with the same persnr but different matrikelnr.
So for every row of the table you will get as many as rows as there are for the same persnrs but different matrikelnrs.
For example for the 1st row with persnr = 101 and matrikelnr = 8532478 you will get 2 rows because there are 2 rows in the table with persnr = 101 and matrikelnr <> 8532478.
You are right. It's the cartesian product's fault. Suppose you have persnr 1,1,1,2,2,2 in the first table and persnr 1,1,1,2,2 in the second. How many lines are you expecting to be returned?
In pdeuso-code it would go like this
Select
...
WHERE persnr in (second table)
-- 6 lines
Select persnr
FROM ...
JOIN ... ON a.persnr = b.persnr
-- 3X3 + 3X2 = 15 lines.
SELECT DISTINCT persnr
FROM ...
JOIN ... ON a.persnr = b.persnr
-- 2 lines (1 and 2)
Take your pick
Ok, I am stuck on this one.
I have a PostgreSQL table customers that looks like this:
id firm1 firm2 firm3 firm4 firm5 lastname firstname
1 13 8 2 0 0 Smith John
2 3 2 0 0 0 Doe Jane
Each row corresponds to a client/customer. Each client/customer can be associated with one or multiple firms; the numeric value under each firm# columns corresponds to the firm id in a different table.
So I am looking for a way of returning all rows of customers that are associated with a specific firm.
For example, SELECT id, lastname, firstname where 8 exists in firm1, firm2, firm3, firm4, firm5 would just return the John Smith row as he is associated with firm 8 under the firm2 column.
Any ideas on how to accomplish that?
You can use the IN operator for that:
SELECT *
FROM customer
where 8 IN (firm1, firm2, firm3, firm4, firm5);
But it would be much better in the long run if your normalized your data model.
You should consider to normalize your tables, with the current schema you should join firms tables as many times as the number of firm fields in your customer table.
select *
from customers c
left join firms f1
on f1.firm_id = c.firm1
left join firms f2
on f2.firm_id = c.firm2
left join firms f3
on f3.firm_id = c.firm3
left join firms f4
on f4.firm_id = c.firm4
You can "unpivot" using a combination of array and unnest, as specified in this answer: unpivot and PostgreSQL.
In your case, I think this should work:
select lastname,
firstname,
unnest(array[firm1, firm2, firm3, firm4, firm5]) as firm_id
from customer
Now you can select from this table (using either a with statement or an inner query) where firm_id is the value you care about
I have a value table and I need to write a case statement that touches 2 columns: Below is the example
Type State Min Max Value
A TX 2 15 100
A TX 16 30 200
A TX 31+ 500
Let say I have another table that has the following
Type State Weight Value
A TX 14 ?
So when I join the table , I need a case statement that looks at weight from table 2 , type and state - compare it to the table 1 , know that the weight falls between 2 and 15 from row 1 and update Value in table 2 with 100
Is this doable ?
Thanks
It returns 0 if there aren't rows in this range of values.
select Type, State, Weight,
(select coalesce(Value, 0)
from table_b
where table_b.Type = table_a.Type
and table_b.State = table_a.State
and table_a.Value between table_b.Min and table_b.Max) as Value
from table_a
For an Alteryx solution: (1) run both tables into a Join tool, joining on Type and State; (2) Send the output to a Filter tool where you force Weight to be between Min and Max; (3) Send that output to a Select tool, where you grab only the specific columns you want; (since the Join will give you all columns from all tables). Done.
Caveats: the data running from Join to Filter could be large, since you are joining every Type/State combination in the Lookup table to the other table. Depending on the size of your datasets, that might be cumbersome. Alteryx is very fast though, and at least we're limiting on State and Type, so if your datasets aren't too large, this simple solution will work fine.
With larger data, try to do it as part of your original select, utilizing one of the other solutions given here for your SQL query.
Considering that Min and Max columns in first table are of Integer type
You need to use INNER JOIN on ranges
SELECT *
FROM another_table a
JOIN first_table b
ON a.type = b.type
AND a.State = b.State
AND a.Weight BETWEEN b.min AND b.max
In my table, I have data that looks like this:
CODE DATE PRICE
100 1/1/13 $500
100 2/1/13 $521
100 3/3/13 $530
100 5/9/13 $542
222 3/3/13 $20
350 1/1/13 $200
350 3/1/13 $225
Is it possible to create query to pull out the TWO most recent records by DATE? AND only if there are 2+ dates for a specific code. So the result would be:
CODE DATE PRICE
100 5/9/13 $542
100 3/3/13 $530
350 3/1/13 $225
350 1/1/13 $200
Bonus points if you can put both prices/dates on the same line, like this:
CODE OLD_DATE OLD_PRICE NEW_DATE NEW_PRICE
100 3/3/13 $530 5/9/13 $542
350 1/1/13 $200 3/1/13 $225
Thank you!!!
I managed to solve it with 5 sub-queries and 1 rollup query.
First we have a subquery that gives us the MAX date for each code.
Next, we do the same subquery, except we exclude our previous results.
We assume that your data is already rolled up and you won't have duplicate dates for the same code.
Next we bring in the appropriate Code / Price for the latest and 2nd latest date. If a code doesn't exist in the 2nd Max query - then we don't include it at all.
In the union query we're combining the results of both. In the Rollup Query, we're sorting and removing null values generated in the union.
Results:
CODE MaxOfOLDDATE MaxOfOLDPRICE MaxOfNEWDATE MaxOfNEWPRICE
100 2013-03-03 $530.00 2013-05-09 542
350 2013-01-01 $200.00 2013-03-01 225
Using your Data in a table called "Table", create the following queries:
SUB_2ndMaxDatesPerCode:
SELECT Table.CODE, Max(Table.Date) AS MaxOfDATE1
FROM SUB_MaxDatesPerCode RIGHT JOIN [Table] ON (SUB_MaxDatesPerCode.MaxOfDATE = Table.DATE) AND (SUB_MaxDatesPerCode.CODE = Table.CODE)
GROUP BY Table.CODE, SUB_MaxDatesPerCode.CODE
HAVING (((SUB_MaxDatesPerCode.CODE) Is Null));
SUB_MaxDatesPerCode:
SELECT Table.CODE, Max(Table.Date) AS MaxOfDATE
FROM [Table]
GROUP BY Table.CODE;
SUB_2ndMaxData:
SELECT Table.CODE, Table.Date, Table.PRICE
FROM [Table] INNER JOIN SUB_2ndMaxDatesPerCode ON (Table.DATE = SUB_2ndMaxDatesPerCode.MaxOfDATE1) AND (Table.CODE = SUB_2ndMaxDatesPerCode.Table.CODE);
SUB_MaxData:
SELECT Table.CODE, Table.Date, Table.PRICE
FROM ([Table] INNER JOIN SUB_MaxDatesPerCode ON (Table.DATE = SUB_MaxDatesPerCode.MaxOfDATE) AND (Table.CODE = SUB_MaxDatesPerCode.CODE)) INNER JOIN SUB_2ndMaxDatesPerCode ON Table.CODE = SUB_2ndMaxDatesPerCode.Table.CODE;
SUB_Data:
SELECT CODE, DATE AS OLDDATE, PRICE AS OLDPRICE, NULL AS NEWDATE, NULL AS NEWPRICE FROM SUB_2ndMaxData;
UNION ALL SELECT CODE, NULL AS OLDDATE, NULL AS OLDPRICE, DATE AS NEWDATE, PRICE AS NEWPRICE FROM SUB_MaxData;
Data (Rollup):
SELECT SUB_Data.CODE, Max(SUB_Data.OLDDATE) AS MaxOfOLDDATE, Max(SUB_Data.OLDPRICE) AS MaxOfOLDPRICE, Max(SUB_Data.NEWDATE) AS MaxOfNEWDATE, Max(SUB_Data.NEWPRICE) AS MaxOfNEWPRICE
FROM SUB_Data
GROUP BY SUB_Data.CODE
ORDER BY SUB_Data.CODE;
There you go - thanks for the challenge.
Accessing the recent data
To access the recent data, you use TOP 2. Such as you inverse the data from the table, then select the top 2. Just as you start ABC from ZYX and select the TOP 2 which would provide you with ZY.
SELECT TOP 2 * FROM table_name ORDER BY column_time DESC;
This way, you reverse the table, and then select the most recent two from the top.
Joining the Tables
To join the two columns and create a result from there quest you can use JOIN (INNER JOIN; I prefer this) such as:
SELECT TOP 2 * FROM table_name INNER JOIN table_name.column_name ON
table_name.column_name2
This way, you will join both the tables where a value in one column matches the value from the other column in both tables.
You can use a for loop for this to select the value for them, or you can use this inside the foreach loop to take out the values for them.
My suggestion
My best method would be to, first just select the data that was ordered using the date.
Then inside the foreach() loop where you will write the data for that select the remaining data for that time. And write it inside that loop.
Code (column_name) won't bother you
And when you will reference the query using ORDER By Time Desc you won't be using the CODE anymore such as WHERE Code = value. And you will get the code for the most recent ones. If you really need the code column, you can filter it out using and if else block.
Reference:
http://technet.microsoft.com/en-us/library/ms190014(v=sql.105).aspx (Inner join)
http://www.w3schools.com/sql/sql_func_first.asp (top; check the Sql Server query)