In MS Access 2000, I have a table named [Stack Trace] from which I should randomly pull 400 records with distinct of one of the text columns.
I looked at one of the examples in here and added an autonumber field to the table and wrote the query as below:
Assume that [Appraisal Name] is the distinct field needed and ID is the autonumbered primary key, what should be the query to find random 400 records with one of the text fields having distinct values?
First query without Distinct [Appraisal Name].
SELECT Top 400 *
FROM (SELECT *,
Rnd(ID) AS RandomValue
FROM [Street Data])
ORDER BY RandomValue ASC
I know I can easily achieve that in sql server with Rank operation. I do not see any helpful links to find rank on varchar/text fields. I tried to find rank using the below query. It did not work out.
SELECT
ID,
[Appraiser Name],
(
SELECT COUNT(*)
FROM [Street Data] WHERE
[Appraiser Name] <= T.[Appraiser Name]
) AS Rank
FROM [Street Data] AS T
ORDER BY ID, [Appraiser Name]
Any helps are appreciated.
I solved it some how. But I welcome if there are any easy ways to do it. I created three queries. First one to find the rank of the Appraiser Name, second one to find the distinct of Appraiser Name and third one is the final query. I tried to use the first one in the query with rank = 1 and it gave me join not supported error. That is bad. When I created another query with rank = 1 and then used it in the final one, it worked.
StreetData_Appraiser
SELECT ID, [Appraiser Name], (
SELECT COUNT([Appraiser Name])
FROM [Street Data]
WHERE [Appraiser Name] = T.[Appraiser Name]
AND ID <= T.ID
) AS Rank
FROM [Street Data] AS T
ORDER BY ID, [Appraiser Name]
StreetData_Distinct_Appraiser (Query to mask the first query and show only distinct records and to avoid invalid join error)
SELECT * FROM StreetData_Appraiser WHERE Rank = 1
Final Query
SELECT TOP 400 *
FROM (SELECT ST.*,
Rnd(ST.ID) AS RandomValue
FROM [Street Data] AS ST
INNER JOIN [StreetData_Distinct_Appraiser] AS SA ON SA.ID=ST.ID) AS STRecs
ORDER BY RandomValue
Related
I am wondering if there is a way to make this work. I am deriving a table "WHERE lie_start='green'" (and a bunch of other conditions which i don't wanna repeat), need to get the number (and several other information) off it.
Additionally I need the number of entries with the additional condition lie_finish='holed'. Currently I'm gettin the error: Table mydb.x doesnt exist.
SELECT
COUNT(*) AS total,
(SELECT COUNT(*) FROM x WHERE lie_finish='holed') as holed
FROM (SELECT * FROM mydb.strokes WHERE lie_start='green') as x
You need to repeat the table name. The table alias is not recognized:
SELECT COUNT(*) AS total,
(SELECT COUNT(*) FROM mydb.strokes WHERE lie_finish='holed') as holed
FROM (SELECT * FROM mydb.strokes WHERE lie_start='green') as x;
However, this is much more simply written as:
select count(*) as total, sum(lie_finish = 'holed') as holed
from mydb.strokes s
where lie_start = 'green';
SELECT area_id,
area_name,
(select count(*) from applications
where claims_status=1 and
center_name=c.area_id) as cont
FROM apparea c where cont<>0
I am trying to get fields and relevant count from anothere table, but the above query is not working. The query is involved two different tables(apparea, applications). The above query has error and I am looking for the alternate way to achieve this.
The alias for your column cont is not available in the WHERE clause. You will want to use something similar to this:
SELECT area_id,
area_name,
cont
FROM
(
SELECT area_id,
area_name,
(select count(*)
from applications
where claims_status=1
and center_name=c.area_id) as cont
FROM apparea c
) c
where cont<>0
This can also be written using a LEFT JOIN:
select c.area_id,
c.area_name,
a.cont
from apparea c
left join
(
select count(*) cont,
center_name
from applications
where claims_status=1
group by center_name
) a
on c.area_id = a.center_name
Try this query
SELECT
c.area_id,
c.area_name,
cnt
FROM
apparea c,
(select
center_name,
count(*) AS cnt
from
applications
where
claims_status=1
GROUP BY
center_name
HAVING
count(*) > 0) cont
where
c.area_id = cont.center_name;
Got the count for each center_name and then joined table to get count for each area
Use HAVING rather than where.
As it is problem with aliases.
It is not permissible to refer to a column alias in a WHERE clause, because the column
value might not yet be determined when the WHERE clause is executed.
See Section C.5.5.4, “Problems with Column Aliases”.
http://dev.mysql.com/doc/refman/5.0/en/problems-with-alias.html
From: http://dev.mysql.com/doc/refman/5.0/en/select.html
I'm sure this will be quite simple for some one clued up in SQL but I think it needs a sub query or something. I have a table which basically has a load of order numbers in it and a reply column from an XML API. Either FAIL or SUCCESS.
A brand new row is inserted into the DB after every request. So there may be 5 FAILS for one order number, and on the 6th attempt a record is inserted saying SUCCESS.
How can I put out order numbers that ONLY have a FAIL status next to them?
This will allow me to figure out what records need looking into that continuously fail in the API request.
Try this, by grouping your orders with primary key (order_id)
SELECT * FROM
(
SELECT GROUP_CONCAT(status) as status_combined, order_id
FROM orders
GROUP BY order_id
) AS order_tmp
WHERE status_combined NOT LIKE '%SUCCESS%'
Edit (As per asker comments)
SELECT * FROM
(
SELECT GROUP_CONCAT(status) as status_combined, order_id
FROM orders
JOIN certificates ON certificates.Ordernumber = orders.OrderNumber
GROUP BY order_id
) AS order_tmp
WHERE status_combined NOT LIKE '%SUCCESS%'
please make sure you need to join based on "Ordernumber" or "order_id"
Try this
select m.*
from Main m
join Transactiontable tt
on m.orderid = tt.orderid
group by tt.status , m.orderid
having count(case when tt.status = "failed") = count(tt.status)
You can use simple sql query using a where clause:
select *
from some_table
where Column_From_some_table_has_value = your_particular_value
thats enough.
You can have a look at How to use where clause in sql
Thanks
This is probably the cleanest way to do it:
select *
from mytable
where id in (
select id
from mytable
group by id
having sum(status = 'SUCCESS') = 0)
I'm not a fan of #Minesh's answer because it uses both an aggregate function and the LIKE operator. Both of those can cause performance issues since there won't be any indexes to help the query out with the difficult part of the work. The LIKE clause particularly is a lot of work for the database since it will need to scan every result.
I'm more familiar with SQL Server, but this should work well for you:
SELECT *
FROM Orders
WHERE OrderNumber NOT IN (
SELECT OrderNumber
FROM Orders
WHERE Status = 'SUCCESS')
AND OrderNumber NOT IN (
SELECT OrderNumber
FROM Certificates
WHERE OrderStatus = 'CANCELLED')
I have something like this:
SELECT id, fruit, pip
FROM plant
WHERE COUNT(*) = 2;
This weird query is self explanatory I guess. COUNT(*) here means the number of rows in plant table. My requirement is that I need to retrieve values from specified fields only if total number of rows in table = 2. This doesn't work but: invalid use of aggregate function COUNT.
I cannot do this:
SELECT COUNT(*) as cnt, id, fruit, pip
FROM plant
WHERE cnt = 2;
for one, it limits the number of rows outputted to 1, and two, it gives the same error: invalid use of aggregate function.
What I can do is instead:
SELECT id, fruit, pip
FROM plant
WHERE (
SELECT COUNT(*)
FROM plant
) = 2;
But then that subquery is the main query re-run. I'm presenting here a small example of the larger part of the problem, though I know an additional COUNT(*) subquery in the given example isn't that big an overhead.
Edit: I do not know why the question is downvoted. The COUNT(*) I'm trying to get is from a view (a temporary table) in the query which is a large query with 5 to 6 joins and additional where clauses. To re-run the query as a subquery to get the count is inefficient, and I can see the bottleneck as well.
Here is the actual query:
SELECT U.UserName, E.Title, AE.Mode, AE.AttemptNo,
IF(AE.Completed = 1, 'Completed', 'Incomplete'),
(
SELECT COUNT(DISTINCT(FK_QId))
FROM attempt_question AS AQ
WHERE FK_ExcAttemptId = #excAttemptId
) AS Inst_Count,
(
SELECT COUNT(DISTINCT(AQ.FK_QId))
FROM attempt_question AS AQ
JOIN `question` AS Q
ON Q.PK_Id = AQ.FK_QId
LEFT JOIN actions AS A
ON A.FK_QId = AQ.FK_QId
WHERE AQ.FK_ExcAttemptId = #excAttemptId
AND (
Q.Type = #descQtn
OR Q.Type = #actQtn
AND A.type = 'CTVI.NotImplemented'
AND A.IsDelete = #status
AND (
SELECT COUNT(*)
FROM actions
WHERE FK_QId = A.FK_QId
AND type != 'CTVI.NotImplemented'
AND IsDelete = #status
) = 0
)
) AS NotEvalInst_Count,
(
SELECT COUNT(DISTINCT(FK_QId))
FROM attempt_question AS AQ
WHERE FK_ExcAttemptId = #excAttemptId
AND Mark = #mark
) AS CorrectAns_Count,
E.AllottedTime, AE.TimeTaken
FROM attempt_exercise AS AE
JOIN ctvi_exercise_tblexercise AS E
ON AE.FK_EId = E.PK_EId
JOIN ctvi_user_table AS U
ON AE.FK_UId = U.PK_Id
JOIN ctvi_grade AS G
ON AE.FK_GId = G.PK_GId
WHERE AE.PK_Id = #excAttemptId
-- AND COUNT(AE.*) = #number --the portion in contention.
Kindly ignore the above query and guide me to right direction from the small example query I posted, thanks.
In MySQL, you can only do what you tried:
SELECT id, fruit, pip
FROM plant
WHERE (
SELECT COUNT(*)
FROM plant
) = 2;
or this variation:
SELECT id, fruit, pip
FROM plant
JOIN
(
SELECT COUNT(*) AS cnt
FROM plant
) AS c
ON c.cnt = 2;
Whether the 1st or the 2nd is more efficient, depends on the version of MySQL (and the optimizer). I would bet on the 2nd one, on most versions.
In other DBMSs, that have window functions, you can also do the first query that #Andomar suggests.
Here is a suggestion to avoid the bottleneck of calculating the derived table twice, once to get the rows and once more to get the count. If the derived table is expensive to be calculated, and its rows are thousands or millions, calculating them twice only to throw them away, is a problem, indeed. This may improve efficiency as it will limit the intermediately (twice) calculated rows to 3:
SELECT p.*
FROM
( SELECT id, fruit, pip
FROM plant
LIMIT 3
) AS p
JOIN
( SELECT COUNT(*) AS cnt
FROM
( SELECT 1
FROM plant
LIMIT 3
) AS tmp
) AS c
ON c.cnt = 2 ;
After re-reading your question, you're trying to return rows only if there are 2 rows in the entire table. In that case I think your own example query is already the best.
On another DBMS, you could use a Windowing function:
select *
from (
select *
, count(*) over () as cnt
from plant
) as SubQueryAlias
where cnt = 2
But the over clause is not supported on MySQL.
old wrong anser below
The where clause works before grouping. It works on single rows, not groups of rows, so you can't use aggregates like count or max in the where clause.
To set filters that work on groups of rows, use the having clause. It works after grouping and can be used to filter with aggregates:
SELECT id, fruit, pip
FROM plant
GROUP BY
id, fruit, pip
HAVING COUNT(*) = 2;
The other answers do not fulfill the original question which was to filter the results "without using a subquery".
You can actually do this by using a variable in 2 consecutive MySQL statements:
SET #count=0;
SELECT * FROM
(
SELECT id, fruit, pip, #count:=#count+1 AS count
FROM plant
WHERE
) tmp
WHERE #count = 2;
Basically, I am trying to create some sort of 'high score' - I will have to gather all users' total experience, and total level information from the database, but I want to add a temporary MySQL column to the query (which will be an integer), so I can know right away what their ranking is.
Here is my query so far:
SELECT characters_statistics.total_level,
characters_statistics.total_exp,
characters.username
FROM characters_statistics
INNER JOIN characters ON characters.id = characters_statistics.master_id
ORDER BY total_exp DESC
Try this:
SET #rownum = 0;
Select sub.*, sub.rank as Rank
FROM
(
Select *, (#rownum:=#rownum+1) as rank
FROM YourTableName
) sub