i'm working with db2
so i have some table and the question is how to fill all empty code fields
raws in the table represent some real world hierarchy
so i need to put non empty value of the CODE field into empty CODE fields according to information in the field LINK
my table is like that
Objid link code
1 0 555
2 1
3 2
4 3
ideally i need to do this inside one CREATE TABLE ... AS SELECT operator to create an mqt which would be later automatically refreshed on the regular base
all i have created by now is
CASE
WHEN (code is NULL or code = '')
THEN (select code from some_other_table
where objid = link and code is not NULL
)
WHEN (code != '' and code is not NULL)
THEN code
ELSE NULL
END AS code,
i think it must be some kind of while loop which i can't put inside my CREATE TABLE AS SELECT
Are there any solutions without using procedures or functions?
I think what you might be looking for is a "select for update" type query. This can be done similar to the following:
UPDATE SOME_DB.SOME_TABLE A
SET CODE = (SELECT SOME_CODE_FIELD
FROM SOME_OTHER_DB.SOME_OTHER_TABLE B
WHERE A.KEY = B.KEY)
WHERE CODE IS NOT NULL
OR CODE = "";
This will update table A with the code value from table B, if it has one, for all rows on table A with a null code. If table B has no code value, I believe the subselect will return null (provided the code column in table B is nullable) and the value of that code on table A will remain null.
If you are doing a CREATE TABLE AS SELECT, can't you just join to the table that has the missing code?
SELECT
COALESCE(CASE WHEN code='' THEN null ELSE code END,so.code) as code
FROM CodeTable ct
LEFT JOIN SomeOtherCodeTable so ON
ct.objid = so.link
AND so.code IS NOT NULL
Related
I need to check if one or many fields already exists in a table so I can do a merge into statement using them.
I tried this:
select sat_sector_hkey,
CASE
WHEN EXISTS(select id from hub_sector)
THEN (MERGE INTO ...)
END AS id
from sat_sector;
For testing, I used only one case statement, and replaced merge into with a THEN...ELSE values:
SELECT sat_sector_hkey,
CASE
WHEN EXISTS(select id from hub_sector)
THEN '1'
ELSE ''
END AS id
FROM sat_sector;
When this field does not exists, the query return an error instead of '':
SQL compilation error: error line 3 at position 23 invalid identifier
'ID'
I am using a CASE, because I need to check if a column exists or not, as I don't know if it exists or not due to some technicalities in our data coming from multiple sources.
Try this:
Construct an object with the full row.
Test if the constructed object has data for "ID".
create or replace temp table maybe_id
as
select 1 x, 2 id;
select *,
case
when object_construct(a.*):ID is not null
then '1'
else ''
end as id
from maybe_id a
;
Works for me - it gives 1 when the column id has data, and `` when the column doesn't exist in the table.
I am fairly new to SQL. What I am trying to do is create a view from an existing table. I also need to add a new column to the view which maps to the values of an existing column in the table.
So within the view, if the value in a field for Col_1 = A, then the value in the corresponding row for New_Col = C etc
Does this even make sense? Would I use the CASE clause? Is mapping in this way even possible?
Thanks
The best way to do this is to create a mapping or lookup table
For example consider the following LOOKUP table.
COL_A NEW_VALUE
---- -----
A C
B D
Then you can have a query like this:
SELECT A.*, LOOK.NEW_VALUE
FROM TABLEA AS A
JOIN LOOKUP AS LOOK ON A.COL_A = LOOK.COL_A
This is what DimaSUN is doing in his query too -- but in his case he is creating the table dynamically in the body of the query.
Also note, I'm using a JOIN (which is an inner join) so only results in the lookup table will be returned. This could filter the results. A LEFT JOIN there would return all data from A but some of the new columns might be null.
Generally, a view is an instance of a table/a replica provided that there is no alteration to the original table. So, as per your query you can manipulate the data and columns in a view by using case.
Create View viewname as
Select *,
case when column=a.value then 'C'
....
ELSE
END
FROM ( Select * from table) a
If You have restricted list of replaced values You may hardcode that list in query
select T.*,map.New_Col
from ExistingTable T
left join (
values
('A','C')
,('B','D')
) map (Col_1,New_Col) on map.Col_1 = T.Col_1
In this sample You hardcode 'A' -> 'C' and 'B' -> 'D'
In general case You better may to use additional table ( see Hogan answer )
I have to compare comma separated values with a column in the table and find out which values are not in database. [kind of master data validation]. Please have a look at the sample data below:
table data in database:
id name
1 abc
2 def
3 ghi
SQL part :
Here i am getting comma separated list like ('abc','def','ghi','xyz').
now xyz is invalid value, so i want to take that value and return it as output saying "invalid value".
It is possible if i split those value, take it in temp table, loop through each value and compare one by one.
but is there any other optimal way to do this ??
I'm sure if I got the question right, however, I would personally be trying to get to something like this:
SELECT
D.id,
CASE
WHEN B.Name IS NULL THEN D.name
ELSE "invalid value"
END
FROM
data AS D
INNER JOIN badNames B ON b.Name = d.Name
--as SQL is case insensitive, equal sign should work
There is one table with bad names or invalid values if You prefer. This can a temporary table as well - depending on usage (a black-listed words should be a table, ad hoc invalid values provided by a service should be temp table, etc.).
NOTE: The select above can be nested in a view, so the data remain as they were, yet you gain the correctness information. Otherwise I would create a cursor inside a function that would go through the select like the one above and alter the original data, if that is the goal...
It sounds like you just need a NOT EXISTS / LEFT JOIN, as in:
SELECT tmp.InvalidValue
FROM dbo.HopeThisIsNotAWhileBasedSplit(#CSVlist) tmp
WHERE NOT EXISTS (
SELECT *
FROM dbo.Table tbl
WHERE tbl.Field = tmp.InvalidValue
);
Of course, depending on the size of the CSV list coming in, the number of rows in the table you are checking, and the style of splitter you are using, it might be better to dump the CSV to a temp table first (as you mentioned doing in the question).
Try following query:
SELECT SplitedValues.name,
CASE WHEN YourTable.Id IS NULL THEN 'invalid value' ELSE NULL END AS Result
FROM SplitedValues
LEFT JOIN yourTable ON SplitedValues.name = YourTable.name
Hi my problem is I want to update a field in 1 table using another field from several tables dependant upon where the item originates my only problem is the table which im trying to update has several of the same values in so am getting 'single row sub-query returns more than 1 row'. I dont mind all of the updated fields with the same value being the same. Heres my SQL:
update URL_SET_TAB u
Set U.ITEM_NAME = (select a.PROGRAMME_NAME
from (SELECT (nvl(nvl(b.prog_name,c.movie_name), A.URL_1)) as programme_name, a.ID, a.URL_1
FROM URL_SET_TAB a, prog_name_lookup b, movie_name_lookup c
where a.url_1 = b.url_1(+) and a.url_1 = C.MOVIE_URL(+)
) a
where u.ID = a.ID and U.URL_1 = a.URL_1
)
You need to identify a key column which when matched for URL_SET_TAB and inline view a so that the subquery returns only a single record. This is a limitaion of an UPDATE clause.
Thanks,
Aditya
Been reading this site for answers for quite a while and now asking my first question!
I'm using SQL Server
I have two tables, ABC and ABC_Temp.
The contents are inserted into the ABC_Temp first before making its way to ABC.
Table ABC and ABC_Temp have the same columns, except that ABC_Temp has an extra column called LastUpdatedDate, which contains the date of the last update. Because ABC_Temp can have more than 1 of the same record, it has a composite key of the item number and the last updated date.
The columns are: ItemNo | Price | Qty and ABC_Temp has an extra column: LastUpdatedDate
I want to create a statement that follows the following conditions:
Check if each of the attributes of ABC differ from the value of ABC_Temp for records with the same key, if so then do the update (Even if only one attribute is different, all other attributes can be updated as well)
Only update those that need changes, if the record is the same, then it would not update.
Since an item can have more than one record in ABC_Temp I only want the latest updated one to be updated to ABC
I am currently using 2005 (I think, not at work at the moment).
This will be in a stored procedure and is called inside the VBscript scheduled task. So I believe it is a once time thing. Also I'm not trying to sync the two tables, as the contents of ABC_Temp would only contain new records bulk inserted from a text file through BCP. For the sake of context, this will be used with in conjunction with an insert stored proc that checks if records exist.
UPDATE
ABC
SET
price = T1.price,
qty = T1.qty
FROM
ABC
INNER JOIN ABC_Temp T1 ON
T1.item_no = ABC.item_no
LEFT OUTER JOIN ABC_Temp T2 ON
T2.item_no = T1.item_no AND
T2.last_updated_date > T1.last_updated_date
WHERE
T2.item_no IS NULL AND
(
T1.price <> ABC.price OR
T1.qty <> ABC.qty
)
If NULL values are possible in the price or qty columns then you will need to account for that. In this case I would probably change the inequality statements to look like this:
COALESCE(T1.price, -1) <> COALESCE(ABC.price, -1)
This assumes that -1 is not a valid value in the data, so you don't have to worry about it actually appearing there.
Also, is ABC_Temp really a temporary table that's just loaded long enough to get the values into ABC? If not then you are storing duplicate data in multiple places, which is a bad idea. The first problem is that now you need these kinds of update scenarios. There are other issues that you might run into, such as inconsistencies in the data, etc.
You could use cross apply to seek the last row in ABC_Temp with the same key. Use a where clause to filter out rows with no differences:
update abc
set col1 = latest.col1
, col2 = latest.col2
, col3 = latest.col3
from ABC abc
cross apply
(
select top 1 *
from ABC_Temp tmp
where abc.key = tmp.key
order by
tmp.LastUpdatedDate desc
) latest
where abc.col1 <> latest.col1
or (abc.col2 <> latest.col2
or (abc.col1 is null and latest.col2 is not null)
or (abc.col1 is not null and latest.col2 is null))
or abc.col3 <> latest.col3
In the example, only col2 is nullable. Since null <> 1 is not true, you have to check differences involving null using the is null syntax.