I have table with Billions of Records, Table structure is like :
ID NUMBER PRIMARY KEY,
MY_SEARCH_COLUMN NUMBER,
MY_SEARCH_COLUMN will have Numeric value upto 15 Digit in length.
What I want is, if any specific record is matched, I will have to get that matched value only,
i.e. : If I enter WHERE MY_SEARCH_COLUMN = 123454321 and table has value 123454321 then this only should be returned.
But if exact value is not matched, I will have to get next 10 values from the table.
i.e. : if I enter WHERE MY_SEARCH_COLUMN = 123454321 and column does not have the value 123454321 then it should return 10 values from the table which is greater than 123454321
Both the case should be covered in single SQL Query, and I have have to keep in mind the Performance of the Query. I have already created Index on the MY_SEARCH_COLUMN columns, so other suggestions are welcome to improve the Performance.
This could be tricky to do without using a proc or maybe some dynamic SQL, but we can try using ROW_NUMBER here:
WITH cte AS (
SELECT ID, MY_SEARCH_COLUMN,
ROW_NUMBER() OVER (ORDER BY MY_SEARCH_COLUMN) rn
FROM yourTable
WHERE MY_SEARCH_COLUMN >= 123454321
)
SELECT *
FROM cte
WHERE rn <= CASE WHEN EXISTS (SELECT 1 FROM yourTable WHERE MY_SEARCH_COLUMN = 123454321)
THEN 1
ELSE 10 END;
The basic idea of the above query is that we assign a row number to all records matching the target or greater. Then, we query using either a row number of 1, in case of an exact match, or all row numbers up to 10 in case of no match.
SELECT *
FROM your_table AS src
WHERE src.MY_SEARCH_COLUMN = CASE WHEN EXISTS (SELECT 1 FROM your_table AS src2 WITH(NOLOCK) WHERE src2.MY_SEARCH_COLUMN = 123456321)
THEN 123456321
ELSE src.MY_SEARCH_COLUMN
END
Related
I have two tables one is (providerLoc) and another one is (tmpProviderLoc) I need to take three columns combination from tmpProviderLoc and need to check the records exist in ProviderLoc
Case 1 : If record exist in providerLoc i need to update another column(Npi) in providerLoc based on column (npi) in tmpProviderLoc
case 2 : if not exist i need to insert the values in providerLoc
for that I have written below query:
MERGE INTO [dbo].[ProviderLoc] AS PL
USING
(
select *
from (
select *,
row_number() over (partition by [Location_ID],[PProviderTaxID]
,[POBOXZIP] order by [Location_ID],[PProviderTaxID],[POBOXZIP]) as row_number
from [dbo].[TmpProviderLoc]
) as rows
where row_number = 1
) AS TPL
ON TPL.[Location_ID] = PL.[ecProviderID]
AND TPL.[PProviderTaxID] = PL.[TaxID]
AND TPL.[NPI] = PL.[NPI]
AND TPL.[POBOXZIP] = PL.[POBOXZIP]
WHEN MATCHED THEN
UPDATE SET PL.[NPI] = CASE
WHEN TPL.[NPI] = NULL THEN PL.[NPI]
ELSE TPL.[NPI]
END
WHEN NOT MATCHED THEN
INSERT (EcProviderID,TaxID,NPI,POBOXZIP,ProviderLocationStatusID,CreatedON)
VALUES (TPL.[Location_ID],TPL.[PProviderTaxID],TPL.[NPI]
,TPL.[POBOXZIP],1,GETDATE());
But I am failing in updating the NPI value -- if npi value is new in tmpProviderLoc it is not updating in ProviderLoc..
Could any one please look into this issue..
or any other way to go through this kind of checking
The equal symbol in this is incorrect: WHEN TPL.[NPI] = NULL THEN PL.[NPI]
Use IS NULL
WHEN TPL.[NPI] IS NULL THEN PL.[NPI]
NULLs are special. They are "indeterminate" so they cannot be equal or unequal to anything purely because they just cannot have any value "determined". NULLs are the absence of value and equal/unequal does not apply.
To discover if NULL exists use IS NULL - or - IS NOT NULL to discover if there is a non-null value.
Consider a table that contains a column which has a same value for 100 rows and another one unique. while using select query to retrieve the value which row'th value does it return.
Here is my table structure:
id column_1
1 q
2 q
3 q
4 q
. .
. .
100 q
Here is my query:
DECLARE #UserId INT
SELECT #UserId = Table_1.column_2 FROM [Table_1] WHERE [Table_1].[Column_1] = 'q'
select #UserId
it returns 100 th row value,
May I know why this value came instead of first id which matches condition?
SELECT #UserId = Table_1.column_2 FROM [Table_1] WHERE [Table_1].[Column_1] = 'q'
This produces 100 result rows, each one assigning the #UserId anew.
It seems the last record picked was the one with value 100, so
select #UserId
returns 100. It could have been any other value from the table, as you didn't specify in which order to read the records, however (i.e. there is no ORDER BY clause).
But why do you select all records anyway? You are only interested in one record, the value of which you want to put into the variable. So select only one result value, e.g.:
SELECT #UserId = MIN(column_2) FROM Table_1 WHERE Column_1 = 'q'
When you assign values to variables in the SELECT clause, all values returned by the query are assigned to the variables one by one, from the first to the last, according to the sort order of the results.
In this case, with 100 rows returned, the value assigned to the variable will be the last value in the result set, which is the one for the 100th row.
If you want to assign the first value that matches your condition, use the TOP keyword to limit the number of rows returned. Please keep in mind that without an explicit ORDER BY clause, there is no guarantee on the sort order of the output, so you'd better add it if you want consistent results.
Example:
DECLARE #UserId INT;
SELECT TOP(1) #UserId = Table_1.column_2
FROM [Table_1]
WHERE [Table_1].[Column_1] = 'q'
ORDER BY id;
I need to increase value of next NEWLOSAL row, to be bigger than one, from previous of NEWHISA.
Like HISAL and LOSAL column.
NEWLOSAL need to be previous NEWHISAL + 1.
not that sure if this is what you want:
update table1 t1
set t1.Newlosal=case when t1.grade=1 then (t1.Newhisal+1) else (select t2.Newhisal+1 from table1 t2 where t2.grade = (t1.grade-1)) end
WHERE EXISTS (
SELECT 1
FROM table1 t2
WHERE t2.grade=(t1.grade-1))
This can efficiently be done using the merge statement and a window function:
merge into table1 tg
using
(
select id, -- I assume this is the PK column
lag(newhisal) over (order by grade) + 1 as new_losal
from table1
) nv on (nv.id = tg.id)
when matched then update
set tg.newlosal = nv.new_losal;
In SQL rows in a table (or a result) or not ordered, so the concept of a "previous" row only makes sense if you define a sort order. That's what the over (order by grade) does in the window function. From the screen shot I can not tell by which column this should be sorted.
The screen shot also doesn't reveal the primary key column of your table. I assumed it's named ID. You have to change that to reflect your real PK column name.
I also didn't include a partition by clause in the window function assuming that the formula should be applied for all rows in the same way. If this is not the case you need to be more specific with your sample data.
Currently,I have this objective to meet. I need to query the database for certain results. After done so, I will need to compare the records:
For example: the query return me with 10 rows of records, I then need to compare: row 1 with 2, row 2 with 3, row 3 with 4 ... row 9 with 10.
The final result that I wish to have is 10 or less than 10 rows of records.
I have one approach currently. I do this within a function, hand have the variables call "previous" and "current". In a loop I will always compare previous and current which I populate through the record set using a cursor.
After I got each row of filtered result, I will then input it into a physical temporary table.
After all the results are in this temporary table. I'll do a query on this table and insert the result into a cursor and then returning the cursor.
The problem is: how can I not use a temporary table. I've search through online about using nested tables, but somehow I just could not get it working.
How to replace the temp table with something else? Or is there other approach that I can use to compare the row columns with other rows.
EDIT
So sorry, maybe I am not clear with my question. Here is a sample of the result that I am trying to achieve.
TABLE X
Column A B C D
100 300 99 T1
100 300 98 T2
100 300 97 T3
100 100 97 T4
100 300 97 T5
101 11 11 T6
ColumnA is the primary key of the table. ColumnA has duplicates because table X is an audit table that keep tracks of all changes.column D acts as the timestamp for that record.
For my query, I am only interested in changes in column A,B and D. After the query I would like to get the result as below:
Column A B D
100 300 T1
100 100 T4
100 300 T5
101 11 T6
I think Analytics might do what you want :
select col1, col2, last(col1) over (order by col1, col2) LASTROWVALUE
from table1
this way, LASTROWVALUE will contain de value of col1 for the last row, which you can directly compare to the col1 of the current row.
Look this URL for more info : http://www.orafaq.com/node/55
SELECT ROW_NUMBER() OVER(ORDER BY <Some column name>) rn,
Column1, <Some column name>, CompareColumn,
LAG(CompareColumn) OVER(ORDER BY <Some column name>) PreviousValue,
LEAD(CompareColumn) OVER(ORDER BY <Some column name>) NextValue,
case
when CompareColumn != LEAD(CompareColumn) OVER(ORDER BY <Some column name>) then CompareColumn||'-->'||LEAD(CompareColumn) OVER(ORDER BY <Some column name>)
when CompareColumn = LAG(CompareColumn) OVER(ORDER BY <Some column name>) then 'NO CHANGE'
else 'false'
end
FROM <table name>
You can use this logic in a loop to change behaviour.
Hi It's not very clear what exactly yuo want to accomplish. But maybe you can fetch the results of the original query in a PLSQL collection and use that to do your comparison.
What exactly are you doing the row comparison for? Are you looking to eliminate duplicates, or are you transforming the data into another form and then returning that?
To eliminate duplicates, look to use GROUP BY or DISTINCT functionality in your SELECT.
If you are iterating over the initial data and transforming it in some way then it is hard to do it without using a temporary table - but what exactly is your problem with the temp table? If you are concerned about the performance of a cursor then maybe you could do one outer SELECT that compares the results of two inner SELECTs - but the trick is that the second SELECT is offset by one row, so you achieve the requirement of comparing row 1 against row2, etc.
I think you are complicating things with the temp table.
It can be made using a cursor and 2 temporary variables.
Here is the pseudo code:
declare
v_temp_a%xyz;
v_temp_b%xyz;
i number;
cursor my_cursor is select xyz from xyz;
begin
i := 1;
for my_row in my_cursor loop
if (i = 1)
v_temp_a := my_row;
else
v_temp_b := v_temp_a;
v_temp_a := my_row;
/* at this point v_temp_b has the previous row and v_temp_a has the currunt row
compare them and put whatever logic you want */
end if
i := i + 1;
end loop
end
I am attempting to use a case statement but keep getting errors. Here's the statement:
select TABLE1.acct,
CASE
WHEN TABLE1.acct_id in (select acct_id
from TABLE2
group by acct_id
having count(*) = 1 ) THEN
(select name
from TABLE3
where TABLE1.acct_id = TABLE3.acct_id)
ELSE 'All Others'
END as Name
from TABLE1
When I replace the TABLE1.acct_id in the THEN expression with a literal value, the query works. When I try to use TABLE1.acct_id from the WHEN part of the query, I get a error saying the result is more than one row. It seems like the THEN expression is ignoring the single value that the WHEN statement was using. No idea, maybe this isn't even a valid use of the CASE statement.
I am trying to see names for accounts that have one entry in TABLE2.
Any ideas would be appreciated, I'm kind of new at SQL.
First, you are missing a comma after TABLE1.acct. Second, you have aliased TABLE1 as acct, so you should use that.
Select acct.acct
, Case
When acct.acct_id in ( Select acct_id
From TABLE2
Group By acct_id
Having Count(*) = 1 )
Then ( Select name
From TABLE3
Where acct.acct_id = TABLE3.acct_id
Fetch First 1 Rows Only)
Else 'All Others'
End as Name
From TABLE1 As acct
As others have said, you should adjust your THEN clause to ensure that only one value is returned. You can do that by add Fetch First 1 Rows Only to your subquery.
Then ( Select name
From TABLE3
Where acct.acct_id = TABLE3.acct_id
Fetch First 1 Rows Only)
Fetch is not accepting in CASE statement - "Keyword FETCH not expected. Valid tokens: ) UNION EXCEPT. "
select name from TABLE3 where TABLE1.acct_id = TABLE3.acct_id
will give you all the names in Table3, which have a accompanying row in Table 1. The row selected from Table2 in the previous line doesn't enter into it.
Must be getting more than one value.
You can replace the body with...
(select count(name) from TABLE3 where TABLE1.acct_id = TABLE3.acct_id)
... to narrow down which rows are returning multiples.
It may be the case that you just need a DISTINCT or a TOP 1 to reduce your result set.
Good luck!
I think that what is happening here is that your case must return a single value because it will be the value for the "name" column. The subquery (select acct_id from TABLE2 group by acct_id having count(*) = 1 ) is OK because it will only ever return one value. (select name from TABLE3 where TABLE1.acct_id= TABLE3.acct_id) could return multiple values depending on your data. The problem is you trying to shove multiple values into a single field for a single row.
The next thing to do would be to find out what data causes multiple rows to be returned by (select name from TABLE3 where TABLE1.acct_id= TABLE3.acct_id), and see if you can further limit this query to only return one row. If need be, you could even try something like ...AND ROWNUM = 1 (for Oracle - other DBs have similar ways of limiting rows returned).