I have table with two columns. Depending on the length of the data in one column, I need to join the next column. How can i proceed with this. I have the base SQL up but i cant join the columns together and display both data into one table.
The current table is like this :
ID Code
---------- ----------
ST01 00
ST0105 05
ET2256 56
After a SELECT QUERY, I would like to have
ID
----------
ST0100
ST0105
ET2256
As you can see when ST01 is lesser than 5 characters i will need to add the Code column to it. When the length of the ID is more i do not need to add. How can i achieve. The DB is in production am I am unable to edit, cause all the old applications are configured and running. But the application which I am building uses the 7 character format. So I cant edit the table. I will need to do a select statement only.
SELECT
CASE ID
WHEN ((LEN(ID))<>5) THEN ID=(RTRIM(ID)+LTRIM(Code))
FROM tblID
ORDER BY ID DESC
Based on your explanation I'm guessing:
SELECT
CASE
WHEN ((LEN(ID))<5) THEN (RTRIM(ID)+LTRIM(Code)) ELSE ID END AS ID
FROM tblID
ORDER BY ID DESC
The syntax of your CASE was a bit off, as well as the comparison on length (<>5 vs <5).
Try this:
SELECT
CASE
WHEN LEN(ID) < 6 THEN LEFT(ID + Code),6)
ELSE ID
END AS Code
FROM tblID
ORDER BY ID DESC;
Try this:
SELECT
CASE
WHEN LEN(ID) <> 6 THEN SUBSTRING(ID, 1, 6-LEN(Code)) + Code
ELSE ID
END as Code
FROM tblID
ORDER BY ID DESC;
Related
I have two tables, one with a single row for each "batch_number" and another with defect details for each batch. The first table has a "defect_of_interest" column which I would like to link to one of the columns in the second table. I am trying to write a query that would then pick the maximum value in that dynamically linked column for any "unit_number" in the "batch_number".
Here is the SQLFiddle with example data for each table: http://sqlfiddle.com/#!9/a1c27d
For example, the maximum value in the DEFECT_DETAILS.SCRATCHES column for BATCH_NUMBER = A1 is 12.
Here is my desired output:
BATCH_NUMBER DEFECT_OF_INTEREST MAXIMUM_DEFECT_COUNT
------------ ------------------ --------------------
A1 SCRATCHES 12
B3 BUMPS 4
C2 STAINS 9
I have tried using the PIVOT function, but I can't get it to work. Not sure if it works in cases like this. Any help would be much appreciated.
If the number of columns is fixed (it seems to be) you can use CASE to select the specific value according to the related table. Then aggregating is simple.
For example:
select
batch_number,
max(defect_of_interest) as defect_of_interest,
max(defect_count) as maximum_defect_count
from (
select
d.batch_number,
b.defect_of_interest,
case when b.defect_of_interest = 'SCRATCHES' then d.scratches
when b.defect_of_interest = 'BUMPS' then d.bumps
when b.defect_of_interest = 'STAINS' then d.stains
end as defect_count
from defect_details d
join batches b on b.batch_number = d.batch_number
) x
group by batch_number
order by batch_number;
See Oracle example in db<>fiddle.
Let's say, we have this table:
STUDENT | START | END
1 |1998-1-1 |2001-1-1
2 |1999-1-1 |2001-1-1
3 |2000-1-1 |2004-1-1
4 |2000-1-1 | NULL
I'm trying to do is:
Count number of students between start and end dates!
Looks like you need to use a basic COUNT aggregate:
SELECT COUNT(Student)
FROM YourTable
WHERE Start >= #Start
AND End <= #End
I've used >= and <= respectively around the start and end date fields. Feel free to change to > or < as needed. It was unclear from your question whether you wanted between a specific field or if you were checking for a range between those two fields.
Use the between Operator and COUNT aggregate function
SELECT COUNT(student) column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2
Between can be used with text so insert the dates where the values are,
Read more here if you still don't understand
EDIT : That should work, sorry about the error
http://www.w3schools.com/sql/sql_between.asp
SELECT * FROM tblItems
WHERE itemId IN (9,1,4)
Returns in the order that SQL finds them in (which happens to be 1, 4, 9) however, I want them returned in the order that I specified in the array.
I know I could reorder them after in my native language (obj c), but is there a neat way to do this in SQL?
Somthing like this would be great:
ORDER BY itemId (9,1,4) -- <-- this dosn't work :)
Probably the best way to do this is create a table of item IDs, which also includes a rank order. Then you can join and sort by the rank order.
Create a table like this:
itemID rank
9 1
1 2
4 3
Then your query would look like this:
select tblItems.* from tblItems
inner join items_to_get on
items_to_get.itemID = tblItems.itemID
order by rank
Use a CASE expression to map the ID values to an increasing sequence:
... ORDER BY CASE itemId
WHEN 9 THEN 1
WHEN 1 THEN 2
ELSE 3
END
I had the same task once in a mysql environment.
I ended up using
ORDER BY FIND_IN_SET(itemID, '9,1,4')
this is working for me since then. I hope it also works for sqlite
You can add a case construct to your select clause.
select case when itemid = 9 then 1
when itemid = 1 then 2 else 3 end sortfield
etc
order by sortfield
You could create a procedure to order the data in SQL, but that would be much more complicated than its native language counterpart.
There's no "neat way" to resort the data like that in SQL -- the WHERE clause of a SELECT simply says "if these criteria are matched, include the row"; it's not (and it cannot be) an ordering criterion.
This question already exists:
Closed 10 years ago.
Possible Duplicate:
SQL Select DISTINCT using CAST
Let me try this one more time... I'm not a sql guy so please bear with me as I try to explain this... I have a table called t_recordkeepingleg with three columns of data. Column1 is named LEGTRIPNUMBER that happens to be a string that starts with the letter Q followed by 4 numbers. I need to strip off the Q and convert the remaining 4 characters (numbers) to an integer. Everyone with me so far? Column2 of this table is named LEGDATE. Column3 is named LEGGROUP.
Here's the input scenario
LEGTRIPNUMBER LEGDATE LEGGROUP
Q1001 08/12/12 0001
Q1001 09/15/12 0002
Q1002 09/01/12 0001
Q1002 09/08/12 0003
Q1002 09/09/12 0002
As you can see the input table has rows where LEGTRIPNUMBER occurs more than once. I only want the first occurrence.
This is my current select statement - it works but returns all rows.
SELECT *,
CAST(
substring("t_RecordkeepingLeg"."LEGTRIPNUMBER",2,4) as INT
) as Num_Trip_Num
FROM "1669"."dbo"."t_RecordkeepingLeg" "t_RecordkeepingLeg"
Where left "t_RecordkeepingLeg"."LEGTRIPNUMBER",1) = 'Q'
I want to modify this so that it only selects ONE occurance of the Qnnnn. When the row gets selected I want to have LEGDATE and LEGGROUP available to me. How do I do this?
Thank you,
Can it be as simple as below? I've just added condiotion on leggroup being 0001
SELECT *,
CAST(substring("t_RecordkeepingLeg"."LEGTRIPNUMBER",2,4) as INT) as Num_Trip_Num
FROM "1669"."dbo"."t_RecordkeepingLeg" "t_RecordkeepingLeg"
Where left ("t_RecordkeepingLeg"."LEGTRIPNUMBER",1) = 'Q'
and "t_RecordkeepingLeg"."LEGGROUP"='0001'
If you have a unique primay key in your table you can do something like the below;
SELECT CAST(
substring("t_RecordkeepingLeg"."LEGTRIPNUMBER",2,4) as INT
) as Num_Trip_Num
FROM "1669"."dbo"."t_RecordkeepingLeg" "t_RecordkeepingLeg"
Where "t_RecordkeepingLeg"."ID" In(
Select Min("t_RecordkeepingLeg"."ID")
From "1669"."dbo"."t_RecordkeepingLeg" "t_RecordkeepingLeg"
Where left ("t_RecordkeepingLeg"."LEGTRIPNUMBER",1) = 'Q'
Group By "t_RecordkeepingLeg"."LEGTRIPNUMBER"
)
Which values of LEGDATE & LEGGROUP do you want for the distinct LEGTRIPNUMBER? there are multiple non-distinct possibilities and the concept of "first occurrence" is only valid with an explicit order.
To get the values where LEGDATE is the earliest for example;
select Num_Trip_Num, LEGDATE, LEGGROUP from (
select
cast(substring(t_RecordkeepingLeg.LEGTRIPNUMBER, 2, 4) as INT) as Num_Trip_Num,
row_number() over (partition by substring(t_RecordkeepingLeg.LEGTRIPNUMBER, 2, 4) order by t_RecordkeepingLeg.LEGDATE asc) as row,
t_RecordkeepingLeg.LEGDATE,
t_RecordkeepingLeg.LEGGROUP
from t_RecordkeepingLeg
where left (t_RecordkeepingLeg.LEGTRIPNUMBER, 1) = 'Q'
) T
where row = 1
If we have a table called FollowUp and has rows [ ID(int) , Value(Money) ]
and we have some rows in it, for example
ID --Value
1------70
2------100
3------150
8------200
20-----250
45-----280
and we want to make one SQL Query that get each row ID,Value and the previous Row Value in which data appear as follow
ID --- Value ---Prev_Value
1 ----- 70 ---------- 0
2 ----- 100 -------- 70
3 ----- 150 -------- 100
8 ----- 200 -------- 150
20 ---- 250 -------- 200
45 ---- 280 -------- 250
i make the following query but i think it's so bad in performance in huge amount of data
SELECT FollowUp.ID, FollowUp.Value,
(
SELECT F1.Value
FROM FollowUp as F1 where
F1.ID =
(
SELECT Max(F2.ID)
FROM FollowUp as F2 where F2.ID < FollowUp.ID
)
) AS Prev_Value
FROM FollowUp
So can anyone help me to get the best solution for such a problem ?
This sql should perform better then the one you have above, although these type of queries tend to be a little performance intensive... so anything you can put in them to limit the size of the dataset you are looking at will help tremendously. For example if you are looking at a specific date range, put that in.
SELECT followup.value,
( SELECT TOP 1 f1.VALUE
FROM followup as f1
WHERE f1.id<followup.id
ORDER BY f1.id DESC
) AS Prev_Value
FROM followup
HTH
You can use the OVER statement to generate nicely increasing row numbers.
select
rownr = row_number() over (order by id)
, value
from your_table
With the numbers, you can easily look up the previous row:
with numbered_rows
as (
select
rownr = row_number() over (order by id)
, value
from your_table
)
select
cur.value
, IsNull(prev.value,0)
from numbered_rows cur
left join numbered_rows prev on cur.rownr = prev.rownr + 1
Hope this is useful.
This is not an answer to your actual question.
Instead, I feel that you are approaching the problem from a wrong direction:
In properly normalized relational databases the tuples ("rows") of each table should contain references to other db items instead of the actual values. Maintaining these relations between tuples belongs to the data insertion part of the codebase.
That is, if containing the value of a tuple with closest, smaller id number really belongs into your data model.
If the requirement to know the previous value comes from the view part of the application - that is, a single view into the data that needs to format it in certain way - you should pull the contents out, sorted by id, and handle the requirement in view specific code.
In your case, I would assume that knowing the previous tuples' value really would belong in the view code instead of the database.
EDIT: You did mention that you store them separately and just want to make a query for it. Even still, application code would probably be the more logical place to do this combining.
What about pulling the lines into your application and computing the previous value there?
Create a stored procedure and use a cursor to iterate and produce rows.
You could use the function 'LAG'.
SELECT ID,
Value,
LAG(value) OVER(ORDER BY ID) AS Prev_Value
FROM FOLLOWUP;