I have a table named Route that stores all possible Routes of Trains.
I need to write a query to find all possible Train_ID such that Station_ID of Source = "NDLS" and Station_ID of Destination = "KNP".
My attempt:
Select t.Train_ID from Route as t,Route as d where t.Train_ID = d.Train_ID and t.Stop_Number < d.Stop_Number and t.Station_ID = "KNP" and d.Station_ID = "NDLS";
But this is returning empty set.
select t.train_id
, case when t.station_id = 'NDLS' then t.station_id end as source
, case when t.station_id = 'KNP' then t.station_id end as destination
from route t;
This will give you train_id in first column, second column would be train_id with source as 'NDLS' and third column would be as destination as 'KNP'.
You might get null for destination where source value is presnt and vice versa.
I hope this is ok for you.
Related
Working on a view that pulls from two table however in one table I need to select either one field or another depending on a third..it's the if else that has me stubbed.
Create view as
select
pens.PartNo,
pens.Title,
ranges.weight
if(pens.SpeacialOffer = 1 then pens.offer as Price else pens.Price)
from
pens, ranges
where
pens.penrange = ranges.id;
If the specialoffer is falged the the view needs to pull in the offer else it needs to pull in the Price.
What you need is a CASE operator:
CASE
WHEN condition
THEN value_a
ELSE value_b
END
So in your case:
CASE
WHEN pens.SpeacialOffer = 1
THEN pens.offer
ELSE pens.price
END
This replaces the entire column definition in your SELECT statement, so the whole view becomes:
Create View as
Select
pens.PartNo,
pens.Title,
ranges.weight,
Case
When pens.SpeacialOffer = 1
Then pens.offer
Else pens.price
End as Price
From
pens, ranges
Where
pens.penrange = ranges.id;
Use CASE, also converted the query to explicit join instead of implicit join
select pens.PartNo,
pens.Title,
ranges.weight,
(Case when
pens.SpeacialOffer = 1 then
pens.offer else pens.Price
end ) as Price
FROM pens,
JOIn ranges
ON pens.penrange = ranges.id;
Here's one way:
Create view as select
pens.PartNo,
pens.Title,
ranges.weight,
(pens.SpeacialOffer * pens.offer + (1 - pens.SpeacialOffer) * pens.price) as Price
from
pens,
ranges
where
pens.penrange = ranges.id;
I am trying to update a field to put relevant data in the location column, so it will not be blank. In this case, I would like to copy airport_address into the location column.
airport_address is varchar(500)
location is varchar(100)
I would like to copy the 1st 100 char of airport_address into location
Any idea why this SQL would not be working?
This returns 563 rows:
SELECT *
FROM tbl_events
WHERE location LIKE ""
This affects 0 rows:
UPDATE tbl_events
SET location = LEFT(airport_address, 100)
WHERE location LIKE ""
This affects 0 rows:
UPDATE tbl_events
SET location = airport_address
WHERE location LIKE ""
Try this:
UPDATE tbl_events
SET location = LEFT(airport_address, 100)
WHERE
( location IS NULL )
OR
( LTRIM(RTRIM(location)) = '' )
I have the following sql that I run in C:
snprintf(sql, 200, "update rec set name = (select name from pers where id = %d )
where id = %d",rec_id , emp_id );
mysql_query(conn, sql) returns a successful result but it's putting 1 in the "rec" table in the "name" field instead of the name, but when I printf the output and use it in MySQL it's working fine.
update rec set name = (select name from pers where id = 104 ) where id = 43
Is there something wrong with my sprintf? Or something has to be added?
I also tried static sql command like this
snprintf(sql,"update rec set name = (select name from pers where id = 104 ) where id = 43");
and it also put 1 in the rec.name
Is that due to count of record returned by the sub query? Can you verify by putting a condition which returns e.g. 2 records so that the name is set to 2? if this is the reason then (though less performing approach) try splitting the queries and see if it works this time.
I have a contact table I wish to query when a certain condition exists. I tried the query below but am getting a syntax error.
SELECT *
FROM contact_details
WHERE contactDeleted` =0
AND IF ( contactVisibility = "private"
, SELECT * FROM contact_details
WHERE contactUserId = 1
, IF( contactVisibility = "group"
, SELECT * FROM contact_details
WHERE contactGroup = 3
)
)
If I'm understanding your question correctly (which is difficult with the lack of info you've provided. Sample datasets and expected outcomes are typically helpful), then I don't believe you need IFs at all for what you want. The following will return contacts that are not deleted and who either have (visibility = "private" and userId = 1) OR (visibility = "group" and group = 3)
SELECT *
FROM contact_details
WHERE contactDeleted = 0
AND (
(contactVisibility = "public")
OR
(contactVisibility = "private" AND contactUserId = 1)
OR
(contactVisibility = "group" AND contactGroup = 3)
)
I am assuming you want to use the IF() function and not the statement which is for stored functions..
Refer to this link for more information on that.
Notice that you have put 2 select statements in there, where the custom return values are supposed to be. So you are returning a SELECT *... now notice that in your upper level sql statement you have an AND.. so you basically writing AND SELECT *.. which will give you the syntax error.
Try using .. AND x IN (SELECT *) .. to find if x is in the returned values.
Let me also list this link to make use of an existing and well written answer which may also applicable to your question.
Presently troubleshooting a problem where running this SQL query:
UPDATE tblBenchmarkData
SET OriginalValue = DataValue, OriginalUnitID = DataUnitID,
DataValue = CAST(DataValue AS float) * 1.335
WHERE
FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND ZEGCodeID IN
(SELECT ZEGCodeID FROM tblZEGCode
WHERE(ZEGCode = 'C004') OR
(LEFT(ZEGParentCode, 4) = 'C004'))
Results in the following error:
Msg 8114, Level 16, State 5, Line 1
Error converting data type nvarchar to float.
The really odd thing is, if I change the UPDATE to SELECT to inspect the values that are retrieved are numerical values:
SELECT DataValue
FROM tblBenchmarkData
WHERE FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND ZEGCodeID IN
(SELECT ZEGCodeID
FROM tblZEGCode WHERE(ZEGCode = 'C004') OR
(LEFT(ZEGParentCode, 4) = 'C004'))
Here are the results:
DataValue
2285260
1205310
Would like to use TRY_PARSE or something like that; however, we are running on SQL Server 2008 rather than SQL Server 2012. Does anyone have any suggestions? TIA.
It would be helpful to see the schema definition of tblBenchmarkData, but you could try using ISNUMERIC in your query. Something like:
SET DataValue = CASE WHEN ISNUMERIC(DataValue)=1 THEN CAST(DataValue AS float) * 1.335
ELSE 0 END
Order of execution not always matches one's expectations.
If you set a where clause, it generally does not mean the calculations in the select list will only be applied to the rows that match that where. SQL Server may easily decide to do a bulk calculation and then filter out unwanted rows.
That said, you can easily write try_parse yourself:
create function dbo.try_parse(#v nvarchar(30))
returns float
with schemabinding, returns null on null input
as
begin
if isnumeric(#v) = 1
return cast(#v as float);
return null;
end;
So starting with your update query that's giving an error (please forgive me for rewriting it for my own clarity):
UPDATE B
SET
OriginalValue = DataValue,
OriginalUnitID = DataUnitID,
DataValue = CAST(DataValue AS float) * 1.335
FROM
dbo.tblBenchmarkData B
INNER JOIN dbo.tblZEGCode Z
ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND (
Z.ZEGCode = 'C004' OR
Z.ZEGParentCode LIKE 'C004%'
)
I think you'll find that a SELECT statement with exactly the same expressions will give the same error:
SELECT
OriginalValue,
DataValue NewOriginalValue,
OriginalUnitID,
DataUnitID OriginalUnitID,
DataValue,
CAST(DataValue AS float) * 1.335 NewDataValue
FROM
dbo.tblBenchmarkData B
INNER JOIN dbo.tblZEGCode Z
ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND (
Z.ZEGCode = 'C004' OR
Z.ZEGParentCode LIKE 'C004%'
)
This should show you the rows that can't convert:
SELECT
B.*
FROM
dbo.tblBenchmarkData B
INNER JOIN dbo.tblZEGCode Z
ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND (
Z.ZEGCode = 'C004' OR
Z.ZEGParentCode LIKE 'C004%'
)
AND IsNumeric(DataValue) = 0
-- AND IsNumeric(DataValue + 'E0') = 0 -- try this if the prior doesn't work
The trick in the last commented line is to tack on things to the string to force only valid numbers to be numeric. For example, if you wanted only integers, IsNumeric(DataValue + '.0E0') = 0 would show you those that aren't.