I have Two table consider tbl1 and tbl2
tbl1
Site
---------
101 - Hold
102 - test
tbl2
Site
---------
101 - Hold
104 - wel
102 - test
I want to check tbl2 data is present in tbl1 . If yes select statement has to return 'Yes' else 'No' ...
EXample
If tbl2 is not having "102-test" then also i have to return 'No'
How can i achieve this.
You do this by looking for a non-match and using this information:
select (case when count(*) = 0 then 'Yes' else 'No' end)
from tbl2 t2
where not exists (select 1 from tbl1 where t1.site = t2.site);
The count(*) guarantees that exactly one row is returned, containing yes or no.
SELECT
CASE EXISTS( SELECT Id FROM tbl2 WHERE Id IN (SELECT Id FROM tbl1))
THEN 'Yes'
ELSE 'No'
END
Checking if tbl2 data exists in tbl1 and returning back the site with value either Yes or No when tbl2 exists in tbl1 or not.
No need to use any aggregate and you have information about all tbl1 site's - which is what you wanted to achieve (according to your question).
SELECT
a.site, CASE WHEN b.site IS NOT NULL THEN 'Yes' ELSE 'No END AS value_exists
FROM
tbl1 a
LEFT JOIN tbl2 b ON
a.site = b.site
If you have duplicate values in tbl1 then you might want to consider adding DISTINCT or GROUP BY clause.
Related
I have tables that are set up as shown below:
Table 1:
ID Name Date
1 a 2000-01-01
2 b 2001-01-01
3 c 2002-01-01`
Table 2:
ID Name
2 b
3 c
I would like to return all in Table 1 and then have a column that will hold a variable of either 'Yes' or 'No', based on whether they exist in Table 2, as shown below.
As shown:
Results:
Name Date Yes/No
a 2000-01-01 No
b 2001-01-01 Yes
c 2002-01-01 Yes
I have:
DECLARE #boolean as varchar(10)
IF EXISTS(
SELECT ID FROM Table 2
)
SET #boolean = 'Yes'
ELSE SET #boolean = 'No'
SELECT Name, Date, #boolean as 'Yes/No'
FROM Table 1
LEFT JOIN Table 2 u ON Table 1.ID = Table 2.ID
However, this returns the results as shown below:
Name Date Yes/No
a 2000-01-01 Yes
b 2001-01-01 Yes
c 2002-01-01 Yes
Any ideas on how to manipulate this query to return what is expected?
One option would be to LEFT JOIN the first table to the second one, and then check each record in the first table to see whether its ID matched anything in the second table.
SELECT t1.Name,
t1.Date,
CASE WHEN t2.ID IS NOT NULL THEN 'Yes' ELSE 'No' END AS [Yes/No]
FROM table1 t1
LEFT JOIN table2 t2
ON t1.ID = t2.ID
Demo here:
Rextester
By using LEFT JOIN and checking using CASE if there is no matching result on the second table (t2.ID IS NULL), you can easily get what you need as below:
SELECT Name, Date, CASE WHEN t2.ID IS NULL THEN 'No' ELSE 'Yes' END AS [Yes/No]
FROM Table1 t1 LEFT JOIN Table2 t2 ON t1.ID = t2.ID
If a left join might return multiple unwanted results you can use outer apply() instead:
select t1.*, [Yes/No]=coalesce(x.Yes,'No')
from table_1 t1
outer apply (
select Yes='Yes'
from table_2 t2
where t1.id = t2.id
) x
Select * , case when exists(select 1 from Table2 as b where b.ID = a.ID and b.Name = a.Name) then 'Yes' else 'No' end as 'Yes/No'
From table1 as a
Your query:
DECLARE #boolean as varchar(10)
IF EXISTS(
SELECT ID FROM Table 2
)
SET #boolean = 'Yes'
will always return true because you only check whether ID exists (which always exists records in table2), you forgot to check that should be the ID exists in table1, and you probably do not do in that way, because the indicator is a dynamic value.
I have 2 tables. One table lists all the records of items we track. The other table contains flags of attributes of the records in the first table.
For example, Table 1 has columns
Tab1ID, Name, Address, Phone
Table 2 has these columns
Tab2ID, Tab1ID, FlagName
There is a 1 to Many relationship between Table1 and Table2 linked by Tab1ID.
I'd like to create a query that has all the records from Table1 in it. However, if one of the records in Table2 has a Flagname=Retired (with a matching Tab1ID) then I want a "Y" to show up in the select column list otherwise an "N".
I think it might look something like this:
Select Name, Address, Phone, (select something in table2)
from Table1
where Tab1ID > 1;
It's the subquery in the column that has me stumped.
Pat
You can use exists:
Select t1.*,
(case when exists (select 1
from table2 t2
where t2.tab1id = t1.tab1id and t2.flagname = 'Retired'
)
then 'Y' else 'N'
end) as retired_flag
from Table1 t1;
I would do a normal join returning multiple records, but convert them to bits with case statements. Then use that as the subquery and pull the max value for each bit column.
select
name
,address
,phone
,max(retired_flag)
from (
select
table1.name
,table1.address
,table1.phone
,case when table2.flagname = 'retired' then 1 else 0 end as [retired_flag]
from table1
left join table2
on table1.tab1id = table2.tab1id
where tab1id > 1
) tbl
group by
name
,address
,phone
I have two tables
Table 1 looks like this
ID Repeats
-----------
A 1
A 1
A 0
B 2
B 2
C 2
D 1
Table 2 looks like this
ID values
-----------
A 100
B 200
C 100
D 300
Using a view I need a result like this
ID values Repeats
-------------------
A 100 NA
B 200 2
C 100 2
D 300 1
that means, I want unique ID, its values and Repeats. Repeats value should display NA when there are multiple values against single ID and it should display the Repeats value in case there is single value for repeats.
Initially I needed to display the max value of repeats so I tried the following view
ALTER VIEW [dbo].[BookingView1]
AS
SELECT bv.*, bd2.Repeats FROM Table1 bv
JOIN
(
SELECT distinct bd.id, bd.Repeats FROM table2 bd
JOIN
(
SELECT Id, MAX(Repeats) AS MaxRepeatCount
FROM table2
GROUP BY Id
) bd1
ON bd.Id = bd1.Id
AND bd.Repeats = bd1.MaxRepeatCount
) bd2
ON bv.Id = bd2.Id;
and this returns the correct result but when trying to implement the CASE it fails to return unique ID results. Please help!!
One method uses outer apply:
select t2.*, t1.repeats
from table2 t2 outer apply
(select (case when max(repeats) = min(repeats) then max(repeats)
else 'NA'
end) as repeats
from table1 t1
where t1.id = t2.id
) t1;
Two notes:
This assumes that repeats is a string. If it is a number, you need to cast it to a string.
repeats is not null.
For the sake of completeness, I'm including another approach that will work if repeats is NULL. However, Gordon's answer has a much simpler query plan and should be preferred.
Option 1 (Works with NULLs):
SELECT
t1.ID, t2.[Values],
CASE
WHEN COUNT(*) > 1 THEN 'NA'
ELSE CAST(MAX(Repeats) AS VARCHAR(2))
END Repeats
FROM (
SELECT DISTINCT t1.ID, t1.Repeats
FROM #table1 t1
) t1
LEFT OUTER JOIN #table2 t2
ON t1.ID = t2.ID
GROUP BY t1.ID, t2.[Values]
Option 2 (does not contain explicit subqueries, but does not work with NULLs):
SELECT DISTINCT
t1.ID,
t2.[Values],
CASE
WHEN COUNT(t1.Repeats) OVER (PARTITION BY COUNT(DISTINCT t1.Repeats), t1.ID) > 1 THEN 'NA'
ELSE CAST(t1.Repeats AS VARCHAR(2))
END Repeats
FROM #table1 t1
LEFT OUTER JOIN #table2 t2
ON t1.ID = t2.ID
GROUP BY t1.ID, t2.[Values], t1.Repeats
NOTE:
This may not give desired results if table2 has different values for the same ID.
I've got a query joining several tables and returning quite a few columns.
An indexed column of another table references the PK of one of these joined tables. Now I would like to add another column to the query that states if at least one row with that ID exists in the new table.
So if I have one of the old tables
ID
1
2
3
and the new table
REF_ID
1
1
1
3
then I'd like to get
ID REF_EXISTS
1 1
2 0
3 1
I can think of several ways to do that, but what is the most elegant/efficient one?
EDIT
I tested the performance of the queries provided with 50.000 records in the old table, every other record matched by two rows in the new table, so half of the records have REF_EXISTS=1.
I'm adding average results as comments to the answers in case anyone is interested. Thanks everyone!
Another option:
select O.ID
, case when N.ref_id is not null then 1 else 0 end as ref_exists
from old_table o
left outer join (select distinct ref_id from new_table) N
on O.id = N.ref_id
I would:
select distinct ID,
case when exists (select 1 from REF_TABLE where ID_TABLE.ID = REF_TABLE.REF_ID)
then 1 else 0 end
from ID_TABLE
Provided you have indexes on the PK and FK you will get away with a table scan and index lookups.
Regards
K
Use:
SELECT DISTINCT t1.id,
CASE WHEN t2.ref_id IS NULL THEN 0 ELSE 1 END AS REF_EXISTS
FROM TABLE_1 t1
LEFT JOIN TABLE_2 t2 ON t2.ref_id = t1.id
Added DISTINCT to ensure only unique rows are displayed.
A join could return multiple rows for one id, as it does for id=1 in the example data. You can limit it to one row per id with a group by:
SELECT
t1.id
, COUNT(DISTINCT t2.ref_id) as REF_EXISTS
FROM TABLE_1 t1
LEFT JOIN TABLE_2 t2 ON t2.ref_id = t1.id
GROUP BY t1.id
The group by ensures there's only one row per id. And count(distinct t2.ref_id) will be 1 if a row is found and 0 otherwise.
EDIT: You can rewrite it without a group by, but I doubt that will make things easer:
SELECT
t1.id
, CASE WHEN EXISTS (
SELECT * FROM TABLE_2 t2 WHERE t2.ref_id = t1.id)
THEN 1 ELSE 0 END as REF_EXISTS
, ....
FROM TABLE_1 t1
I have a table where one column has duplicate records but other columns are distinct. so something like this
Code SubCode version status
1234 D1 1 A
1234 D1 0 P
1234 DA 1 A
1234 DB 1 P
5678 BB 1 A
5678 BB 0 P
5678 BP 1 A
5678 BJ 1 A
0987 HH 1 A
So in the above table. subcode and Version are unique values whereas Code is repeated. I want to transfer records from the above table into a temporary table. Only records I would like to transfer are where ALL the subcodes for a code have status of 'A' and I want them in the temp table only once.
So from example above. the temporary table should only have
5678 and 0987 since all the subcodes relative to 5678 have status of 'A' and all subcodes for 0987 (it only has one) have status of A. 1234 is ommited because its subcode 'DB' has status of 'P'
I'd appreciate any help!
Here's my solution
SELECT Code
FROM
(
SELECT
Code,
COUNT(SubCode) as SubCodeCount
SUM(CASE WHEN ACount > 0 THEN 1 ELSE 0 END)
as SubCodeCountWithA
FROM
(
SELECT
Code,
SubCode,
SUM(CASE WHEN Status = 'A' THEN 1 ELSE 0 END)
as ACount
FROM CodeTable
GROUP BY Code, SubCode
) sub
GROUP BY Code
) sub2
WHERE SubCodeCountWithA = SubCodeCount
Let's break it down from the inside out.
SELECT
Code,
SubCode,
SUM(CASE WHEN Status = 'A' THEN 1 ELSE 0 END)
as ACount
FROM CodeTable
GROUP BY Code, SubCode
Group up the codes and subcodes (Each row is a distinct pairing of Code and Subcode). See how many A's occured in each pairing.
SELECT
Code,
COUNT(SubCode) as SubCodeCount
SUM(CASE WHEN ACount > 0 THEN 1 ELSE 0 END)
as SubCodeCountWithA
FROM
--previous
GROUP BY Code
Regroup those pairings by Code (now each row is a Code) and count how many subcodes there are, and how many subcodes had an A.
SELECT Code
FROM
--previous
WHERE SubCodeCountWithA = SubCodeCount
Emit those codes with have the same number of subcodes as subcodes with A's.
It's a little unclear as to whether or not the version column comes into play. For example, do you only want to consider rows with the largest version or if ANY subcde has an "A" should it count. Take 5678, BB for example, where version 1 has an "A" and version 0 has a "B". Is 5678 included because at least one of subcode BB has an "A" or is it because version 1 has an "A".
The following code assumes that you want all codes where every subcode has at least one "A" regardless of the version.
SELECT
T1.code,
T1.subcode,
T1.version,
T1.status
FROM
MyTable T1
WHERE
(
SELECT COUNT(DISTINCT subcode)
FROM MyTable T2
WHERE T2.code = T1.code
) =
(
SELECT COUNT(DISTINCT subcode)
FROM MyTable T3
WHERE T3.code = T1.code AND T3.status = 'A'
)
Performance may be abysmal if your table is large. I'll try to come up with a query that is likely to have better performance since this was off the top of my head.
Also, if you explain the full extent of your problem maybe we can find a way to get rid of that temp table... ;)
Here are two more possible methods. Still a lot of subqueries, but they look like they will perform better than the method above. They are both very similar, although the second one here had a better query plan in my DB. Of course, with limited data and no indexing that's not a great test. You should try all of the methods out and see which is best for your database.
SELECT
T1.code,
T1.subcode,
T1.version,
T1.status
FROM
MyTable T1
WHERE
EXISTS
(
SELECT *
FROM MyTable T2
WHERE T2.code = T1.code
AND T2.status = 'A'
) AND
NOT EXISTS
(
SELECT *
FROM MyTable T3
LEFT OUTER JOIN MyTable T4 ON
T4.code = T3.code AND
T4.subcode = T3.subcode AND
T4.status = 'A'
WHERE T3.code = T1.code
AND T3.status <> 'A'
AND T4.code IS NULL
)
SELECT
T1.code,
T1.subcode,
T1.version,
T1.status
FROM
MyTable T1
WHERE
EXISTS
(
SELECT *
FROM MyTable T2
WHERE T2.code = T1.code
AND T2.status = 'A'
) AND
NOT EXISTS
(
SELECT *
FROM MyTable T3
WHERE T3.code = T1.code
AND T3.status <> 'A'
AND NOT EXISTS
(
SELECT *
FROM MyTable T4
WHERE T4.code = T3.code
AND T4.subcode = T3.subcode
AND T4.status = 'A'
)
)
In your select, add a where clause that reads:
Select [stuff]
From Table T
Where Exists
(Select * From Table
Where Code = T.Code
And Status = 'A')
And Not Exists
(Select * From Table I
Where Code = T.Code
And Not Exists
(Select * From Table
Where Code = I.Code
And SubCode = I.SubCode
And Status = 'A'))
In English,
Show me the rows,
where there is at least one row with status 'A',
and there are NO rows with any specific subcode,
that do not have at least one row with that code/subcode, with status 'A'
INSERT theTempTable (Code)
SELECT t.Code
FROM theTable t
LEFT OUTER JOIN theTable subT ON (t.Code = subT.Code AND subT.status <> 'A')
WHERE subT.Code IS NULL
GROUP BY t.Code
This should do the trick. The logic is a little tricky, but I'll do my best to explain how it is derived.
The outer join combined with the IS NULL check allows you to search for the absence of a criteria. Combine that with the inverse of what you're normally looking for (in this case status = 'A') and the query succeeds when there are no rows that do not match. This is the same as ((there are no rows) OR (all rows match)). Since we know that there are rows due to the other query on the table, all rows must match.