I am running a query on the table "performance" and I want to insert a column with the same value for all the rows without using alter, update etc.
I wrote a case statement and it works but is there a more refined way?
here is a short query:
SELECT id, name, class,
CASE
WHEN id IS NOT NULL THEN 'Actuals'
ELSE 'Forecast'
END AS type
FROM performance
Basically I need all the values to be labeled "Actuals".
There are many other datasets for which I will use different labels and then append all of them
Just to be clear - don't need to update the table performance itself
use common table expression for your case.
It will add new column in your existing data and you may use this for your further process.
For your point it is not adding nor inserting anything in your existing db structure.
with CTE as (
SELECT id, name, class,
CASE WHEN id IS NOT NULL THEN 'Actuals' ELSE 'Forecast' END AS type
FROM table_performance
)
select * from CTE ----- It give you all the columns from [table] and add another column as you needed.
OR
You may create a view for same, if this condition is fixed.
Related
I want to create a new column in an existing SQL Server table that utilizes state abbreviations (an existing column) to recode the states into a number (1-50) for statistical analysis that will be performed after exporting the output.
Assuming that Alabama is AL = 1 and Wyoming is WY = 50, how would I go about doing this for every state?
Two ways:
Create a lookup table, STATE_ID (with values 1..50) and STATE_ABBREV ('AL' to 'WY'), then join on this table.
Create a large CASE statement:
CASE STATE_ABBR
WHEN 'AL' THEN 1
...
WHEN 'WY' THEN 50
ELSE NULL
END AS STATE_ID
Using a lookup table is really preferred, as this puts the logic into a single place in case it gets used elsewhere. Plus, this is really data, and coding it into a view as code is not the right way to go.
A different approach, if you don't want to use a temporary or lookup table. Create a list of all states in the alphabetical order, and use the charindex function as shown below
create table #temp
( stateCode char(2))
INSERT INTO #temp values ('PA'),('AL'),('NJ'),('MA'),('DC')
select StateCode,charindex(Statecode+'|','AL|PA|NJ|NY|MA|DC|')/3+1 as numb
from #temp
order by numb
Note that charindex is slow, but this approach could be adapted to your computed field if you want.
Again, I think a lookup table is a better solution, but if it has to be a computed field, this should work for you
I have two SQL Server tables, one is my destination table (LocaleStringResource), the other one is the source table (TempResourceSunil).
Source table has the following columns: TempResourceSunil
[ID], [LanguageId], [ResourceName], [ResourceValue], [Burmese], [Unicode]
and the destination table's columns are LocaleStringResource
[Id], [LanguageId], [ResourceName], [ResourceValue]
I want to update the destination table [ResourceValue] based on [ResourceName] from the source file.
Example:
[ResourceName] = 'Account.AccountActivation'
means I want to check it have corresponding Burmese [ResourceValue] in LocaleStringResource table if it does not exist, I will take it from TempResourceSunil and Burmese column and insert it into LocaleStringResource with language id =2.
Same if [ResourceValue] for Unicode (language id = 3) does not exist for [ResourceName] = 'Account.AccountActivation' means I want to insert [ResourceValue] from TempResourceSunil with language id = 3.
Can any SQL expert help me?
The description you gave isn't really fleshed out however, you want to use a Case Statement. CASE STATEMENT INFO
A case statement can have multiple WHENs to cover multiple logic statements. You can even have one inside the other. I wouldn't really do that for this situation.
The example below is just a simple version.
If l.[ResourceValue] is null and l.[ResourceName] = 'Account.AccountActivation' then use the value of T.[Burmese] for column l.[ResourceValue]. ELSE means if no When within the case statement is true, then use this value.
Also be aware that if you are trying to use an INT value from the first table in a string column on the 2nd, you need to cast it as a varchar.
Test out your logic and case statements and see how you get on.
SELECT
l.[Id],
l.[LanguageId],
l.[ResourceName],
CASE WHEN l.[ResourceName] = 'Account.AccountActivation' and l.[ResourceValue] is null then T.[Burmese]
else l.[ResourceValue] end as [ResourceValue],
T.[ID],
T.[LanguageId],
T.[ResourceName],
T.[ResourceValue],
T.[Burmese],
T.[Unicode]
FROM LocaleStringResource as L
LEFT JOIN TempResourceSunil t on (t.ID = L.ID) and (t.[LanguageId] = l.[LanguageId])
I have the following query
SELECT q.pol_id
FROM quot q
,fgn_clm_hist fch
WHERE q.quot_id = fch.quot_id
UNION
SELECT q.pol_id
FROM tdb2wccu.quot q
WHERE q.nr_prr_ls_yr_cov IS NOT NULL
For every row in that result set, I want to create a new row in another table (call it table1) and update pol_id in the quot table (from the above result set) with the generated primary key from the inserted row in table1.
table1 has two columns. id and timestamp.
I'm using db2 10.1.
I've tried numerous things and have been unsuccessful for quite a while. Thanks!
Simple solution: create a new table for the result set of your query, which has an identity column in it. Then, after running your query, update the pol_id field with the newly generated ID in your result table.
Alteratively, you can do it more manually by using the the ROW_NUMBER() OLAP function, which I often found convenient for creating IDs. For this it is convenient to use a stored procedure which does the following:
get the maximum old id from Table1 and write it into a variable old_max_id.
after generating the result set, write the row-numbers into the table1, maybe by something like
INSERT INTO TABLE1
SELECT ROW_NUMBER() OVER (PARTITION BY <primary-key> ORDER BY <whatever-you-want>)
+ OLD_MAX_ID
, CURRENT TIMESTAMP
FROM (<here comes your SQL query>)
Either write the result set into a table or return a cursor to it. Here you should either use the same ROW_NUMBER statement as above or directly use the ID from Table1.
I would like to be able to add columns to a table with cells who's values are computed by need at 'querytime' when (possibly) selecting over them.
Are there some established ways of doing this?
EDIT: Okay I can do without the 'add columns'. What I want is to make a select query which searches some (if they exist) rows with all needed values computed (some function) and also fills in some of the rows which does not have all needed values computed. So each query would do it's part in extending the data a bit.
(Some columns would start out as null values or similar)
I guess I'll do the extending part first and the query after
You use select expression, especially if you don't plan to store the calculation results, or they are dependant on more than one table. An example, as simple as it could be:
SELECT id, (id+1) as next_id FROM table;
What type of database are you asking for? If it is SQL Server then you can use the computed columns by using the AS syntax.
Eg:
create table Test
(
Id int identity(1,1),
col1 varchar(2) default 'NO',
col2 as col1 + ' - Why?'
)
go
insert into Test
default values
go
select * from Test
drop table Test
In the SQL world it's usually expensive to add a column to an existing table so I'd advise against it. Maybe you can manage with something like this:
SELECT OrderID,
ProductID,
UnitPrice*Quantity AS "Regular Price",
UnitPrice*Quantity-UnitPrice*Quantity*Discount AS "Price After Discount"
FROM order_details;
If you really insist on adding a new column, you could go for something like (not tested):
ALTER TABLE order_details ADD column_name datatype
UPDATE order_details SET column_name = UnitPrice+1
You basically ALTER TABLE to add the new column, then perform an UPDATE operation on all the table to set the value of the newly added column.
You can return a single table from a T-SQL Function in SQL Server 2008.
I am wondering if it is possible to return more than one table.
The scenario is that I have three queries that filter 3 different tables. Each table is filtered against 5 filter tables that I would like to return from a function; rather than copy and paste their creation in each query.
An simplified example of what this would look like with copy and paste:
FUNCTION GetValuesA(#SomeParameter int) RETURNS #ids TABLE (ID int) AS
WITH Filter1 As ( Select id FROM FilterTable1 WHERE Attribute=SomeParameter )
, Filter2 As ( Select id FROM FilterTable2 WHERE Attribute=SomeParameter )
INSERT INTO #IDs
SELECT ID FROM ValueTableA
WHERE ColA IN (SELECT id FROM Filter1)
AND ColB IN (SELECT id FROM Filter2)
RETURN
-----------------------------------------------------------------------------
FUNCTION GetValuesB(#SomeParameter int) RETURNS #ids TABLE (ID int) AS
WITH Filter1 As ( Select id FROM FilterTable1 WHERE Attribute=SomeParameter )
, Filter2 As ( Select id FROM FilterTable2 WHERE Attribute=SomeParameter )
INSERT INTO #IDs
SELECT ID FROM ValueTableB
WHERE ColA IN (SELECT id FROM Filter1)
AND ColB IN (SELECT id FROM Filter2)
AND ColC IN (SELECT id FROM Filter2)
RETURN
So, the only difference between the two queries is the Table being filtered, and HOW (the Where clause).
I would like to know if I could return Filter1 & Filter2 from a function. I am also open to suggestions on different ways to approach this problem.
No.
Conceptually, how would you expect to handle a function that returned a variable number of tables? You would JOIN on two tables at once? What if the returned fields don't line up?
Is there some reason you can't have a TVF for each filter?
As others say, NO. A function in TSQL must return exactly one result (although that result can come in the form of a table with numerous values).
There are a couple of ways you could achieve something similar though. A stored procedure can execute multiple select statements and deliver the results up to whatever called it, whether that be an application layer or something like SSMS. Many libraries require you to add additional commands to access more result sets though. For instance, in Pyodbc to access result sets after the first one you need to call cursor.nextset()
Also, inside a function you could UNION several result sets together although that would require each result set to have the same columns. One way to achieve that if they have a different column structure is to add in nulls for the missing columns for each select statement. If you needed to know which select statement returned the value, you could also add a column which indicated that. This should work with your simplified example since in each case it is just returning a single ID column, but it could get awkward very quickly if the column names or types are radically different.