I have 5 words in a column where I need to eliminate two words and show the remaining result
Table name temp
Id approval_trade
1 closed
2 closed by
3 open
4 target
5 running
6 now
I need result as given below using not equal to condition
Id approval_trade
3 open
4 target
5 running
6 now
My query
select *
from temp
where approval_trade <> 'closed' and approval_trade <> 'closed by'
Presumably, you have hidden characters that you cannot see but interfere with the comparison. To start, such a query would normally be written using NOT IN:
select *
from temp
where approval_trade not in ('closed', 'closed by');
This is shorter and less prone to accidental error.
In your case, I would ask if this returns the rows you don't want:
select *
from temp
where approval_trade in ('closed', 'closed by');
If it does, then your query (and the not in) version should work. My guess is that they do not. Next, I would go for like. Does this return only the rows you do not want?
select *
from temp
where approval_trade like 'closed*';
If this returns exactly what you want out, then use not like to get what you want:
where approval_trade not like 'closed*'
If this doesn't work, then the problem gets harder. More understanding of what your data exactly looks like and what the queries return would help.
Related
I am trying to understand this query:
SELECT *
FROM servers
ORDER BY
CASE
WHEN status = "ACTIVE" THEN 1
WHEN status = "INACTIVE" THEN 2
ELSE 3
END
I know this is selecting all rows from the server table and ordering them first with where column status = "ACTIVE" and then where status = "INACTIVE."
What is the syntax THEN 1...THEN 2 ELSE 3 END mean? I know END is to close the case statement, but what are 1, 2, and 3?
Your CASE clause is in the ORDER BY section - it doesn't become part of the output, it's just used by the SQL engine for sorting.
The 1,2,3 are sortable values.
Basically it' saying to put the ACTIVE rows first (1), then the INACTIVE rows (2), then any rows that are neither (3) at the end.
Given that ACTIVE and INACTIVE sort the same way, I guess there are other values in the table that don't sort in that order (maybe CLOSED or DORMANT which would come before INACTIVE
Problem
I've got a dropdown list, which shows all the Article_Group_ID's that are linked to a specific brand, using the following Query:
SELECT TbArticle.Article_Group_ID, TbArticle.Article_Brand_ID
FROM TbArticle
GROUP BY TbArticle.Article_Group_ID, TbArticle.Article_Brand_ID,
HAVING (((TbArticle.Article_Brand_ID)=1))
This works as expected, it returns the following:
Query results
Article_Brand_ID
Article_Group_ID
1
1
1
2
But, if a user does not wish to specify a specific Article_Brand_ID, the query results look like this:
Query
Article_Brand_ID
Article_Group_ID
1
1
2
1
3
1
1
2
As you can see, the same Article_Group_ID is returned three times. Because of this, the user now sees the same group three times, instead of just once. If I were to remove the Article_Brand_ID from the query, the results would look like this:
Article_Group_ID
1
2
Is there any way to achieve the same behavior, by "ignoring" the Article_Brand_ID column, if it's WHERE clause is not set?
Database layout
TbArticle
Article_Brand_ID
Article_Group_ID
1
1
2
1
3
1
1
2
A single query cannot return a variable number of columns. So, strictly speaking you cannot do what you want with a single query. However, if you are willing to accept the second column as NULL when the brand is not provided, then you can adjust the aggregation.
Let me denote the parameter by ?:
SELECT a.Article_Group_ID,
IIF(? IS NOT NULL, a.Article_Brand_ID, NULL) as Article_Brand_ID
FROM TbArticle as a
WHERE a.Article_Brand_ID = ? OR
? IS NULL
GROUP BY a.Article_Group_ID,
IIF(? IS NOT NULL, a.Article_Brand_ID, NULL);
Note: It is usually better to filter before aggregating (i.e. using WHERE) rather than filtering afterwards (i.e. using HAVING).
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
I need some help on this one. I have a query that I need to make work but I need to limit it by the results of another query.
SELECT ItemID, ItemNums
FROM dbo.Tables
ItemNums is a varchar field that is used to store the strings of the various item numbers.
This produces the following.
ItemID ItemNums
1 1, 4, 5
2 1, 3, 4, 5
3 2
4 4
5 1
I have another table that has each item number as an INT that I need to use to pull all ItemIDs that have the associated ItemNums
Something like this.
SELECT *
FROM dbo.Tables
WHERE ItemNums IN (4,5)
Any help would be appreciated.
If possible, you should change your database schema. In general, it's not good to store comma delimited lists in a relational database.
However, if that's not an option, here's one way using a join with like:
select *
from dbo.Tables t
join dbo.SecondTable st on ', '+t.ItemNums+',' like '%, '+st.ItemNumId+',%'
This concatenates commas to the beginning and end of the itemnums to ensure you only match on the specific ids.
I personally would recommend normalizing your dbo.tables.
It would be better as:
ItemID ItemNums
1 1
1 4
1 5
2 1
etc.
Then you can use a join or a sub query to pull out the rows with ItemNums in some list.
Otherwise, it's going to be a mess and not very fast.
I have the following query, which works great. The problem I have is that in both tables (and the aggregate unioned table), there is a field called MTGUID. I need to multiply MTGUID by a number (let's say 1.35, for ease of use) and have it return that number in the MTGUID field. I have tried a dozen ways to do this and can't get anything to play ball. I can create a new column for each calculated price, like (BKRETAIL.MTGUID * 1.35) AS MTG1, but we've got tens of thousands of lines of code that specifically use MTGUID. Any ideas?
I'm using Firebird SQL.
SELECT * FROM (
SELECT BKRETAIL.* FROM BKRETAIL WHERE BKRETAIL.MKEY='SOMEKEY'
UNION SELECT BKWHOLESALE.* FROM BKWHOLESALE WHERE MKEY='SOMEKEY')
ORDER BY
case STATUS
WHEN 'RT' then 1
WHEN 'WH' then 2
WHEN 'OL' then 3
WHEN 'OD' then 4
WHEN NULL then 5
else 6
end;
How about this:
SELECT MTGUID * 1.35 as calculatedMTGUID, SUBSEL.* FROM (
SELECT BKRETAIL.* FROM BKRETAIL WHERE BKRETAIL.MKEY='SOMEKEY'
UNION SELECT BKWHOLESALE.* FROM BKWHOLESALE WHERE MKEY='SOMEKEY') SUBSEL
ORDER BY
case STATUS
WHEN 'RT' then 1
WHEN 'WH' then 2
WHEN 'OL' then 3
WHEN 'OD' then 4
WHEN NULL then 5
else 6
end;
try this
SELECT MTGUID * 1.35 AS MTGUID,<list rest OF COLUMNS here>
FROM (
SELECT BKRETAIL.* FROM BKRETAIL WHERE BKRETAIL.MKEY='SOMEKEY'
UNION SELECT BKWHOLESALE.* FROM BKWHOLESALE WHERE MKEY='SOMEKEY')
ORDER BY
case STATUS
WHEN 'RT' then 1
WHEN 'WH' then 2
WHEN 'OL' then 3
WHEN 'OD' then 4
WHEN NULL then 5
else 6
end;
One option would be to replace the original MTGUID column with computed one, ie
rename the original MTGUID column in table(s);
add new MTGUID column with desired expression using COMPUTED BY (expr);
Advantage of this is that you don't have to alter your SQL statements, disadvantage is that you have to maintain the expression in many places (all the tables which have the column). Of course, the queries which need the original MTGUID value must be updated to use the renamed column, but if the number of such statements is significantly lower it could be worth the trouble.
I think a better solution would be to "hide" all this stuff behind a view but this requires alerting your SQL queries...