Pick another column value depending on column value (postgresql) - postgresql

In my frontend application I have a function that is called pick(VALUE,'col1','col2','col3'). If the VALUE is 2 the value in col2 should be picked.
This is very handsome for replacing long code using "case when", "switch case" or "if else" calculations.
I have tried to find a similar function in Postgres, but no luck so far. Seen some function array() and values() mentioned, but cannot find the correct syntax.
The goal is to set an return on of three column values depending on first column value.
Pseudo code (not working):
Select status values(column1,column2,column3)from code
I know I can do this by using "case-when-then-else-end", but I am looking for a shorter way to achieve the same thing.
Jsfiddle showing the principe. But I only want to pick ONE value depending on type:
http://sqlfiddle.com/#!15/e0b41/10

You can create an array of values from pr_* columns, then pick one of them in this way:
(array[prl_1,prl_2,prl_3])[code_type]
Here is a simple demo: http://sqlfiddle.com/#!15/e0b41/23
select *,
(array[prl_1,prl_2,prl_3])[code_type]
from code
left join prl on prl_id =1

Related

SQL query to extract default (initial) value of a value property

I am trying to create a custom template fragment that builds a table of value properties. I started by creating a SQL query fragment that pulls all properties classified by a Value Type. Now I would like to pull in the default (initial) value assigned. I figured out that it's in the Description table of t_xref, with the property guid in the client field, but I don't know how to write a query that will reliably parse the default value out since the string length may be different depending on other values set. I tried using the template content selector first but I couldn't figure out how to filter to only value properties. I'm still using the default .qeax file but will be migrating to a windows based DBMS soon. Appreciate any help!
Tried using the content selector. Successfully built a query to get value properties but got stuck trying to join and query t_xref for default value.
Edited to add current query and image
Value Properties are block properties that are typed to Value Types. I'm using SysML.
This is my current query, I am no SQL expert! I don't pull anything from t_xref yet but am pulling out only the value properties with this query:
SELECT property.ea_guid AS CLASSGUID, property.Object_Type AS CLASSTYPE, property.Name, property.Note as [Notes], classifier.Name AS TYPE
FROM t_object property
LEFT JOIN t_object classifier ON property.PDATA1 = classifier.ea_guid
LEFT JOIN t_object block on property.ParentID = block.Object_ID
WHERE block.Object_ID = #OBJECTID# AND property.Object_Type = 'Part' AND classifier.Object_Type = 'DataType'
ORDER BY property.Name
I guess that Geert will come up with a more elaborate answer, but (assuming you are after the Run State) here are some details. The value for these Run States is stored in t_object.runstate as one of the crude Sparxian formats. You find something like
#VAR;Variable=v1;Value=4711;Op==;#ENDVAR;
where v1 is the name and 4711 the default in this example. How you can marry that with your template? Not the faintest idea :-/
I can't give a full answer to the original question as I can't reproduce your data, but I can provide an answer for the generic problem of "how to extract data through SQL from the name-value pair in t_xref".
Note, this is heavily dependent on the database used. The example below extracts fully qualified stereotype names from t_xref in SQL Server for custom profiles.
select
substring(
t_xref.Description, charindex('FQName=',t_xref.Description)+7,
charindex(';ENDSTEREO',t_xref.Description,charindex('FQName=',t_xref.Description))
-charindex('FQName=',t_xref.Description)-7
),
Description from t_xref where t_xref.Description like '%FQName%'
This works using:
substring(string, start, length)
The string is the xref description column, and the start and length are set using:
charindex(substring, string, [start position])
This finds the start and end tags within the xref description field, for the data you're trying to parse.
For your data, I imagine something like the below is the equivalent (I haven't tested this). It's then a case of combining it with the query you've already got.
select
substring(
t_xref.Description, #the string to search in
charindex('#VALU=',t_xref.Description,charindex('#NAME=default',t_xref.Description)+6, #the start position, find the position of the first #VALU= tag after name=default
charindex('#ENDVALU;',t_xref.Description,charindex('#VALU=',t_xref.Description))
-charindex('#VALU=',t_xref.Description,charindex('#NAME=default',t_xref.Description))-6 #the length, find the position of the first #ENDVALU tag after the start, and subtract it from the start position
),
Description from t_xref where t_xref.Description like '%#NAME=default%' #filter anything which doesn't contain this tag to avoid "out of range" index errors

SSRS multi value parameter - can't get it to work

First off this is my first attempt at a multi select. I've done a lot of searching but I can't find the answer that works for me.
I have a postgresql query which has bg.revision_key in (_revision_key) which holds the parameter. A side note, we've named all our parameters in the queries with the underscore and they all work, they are single select in SSRS.
In my SSRS report I have a parameter called Revision Key Segment which is the multi select parameter. I've ticked Allow multi value and in Available Values I have value field pointing to revision_key in the dataset.
In my dataset parameter options I have Parameter Value [#revision_key]
In my shared dataset I also have my parameter set to Allow multi value.
For some reason I can't seem to get the multi select to work so I must be missing something somewhere but I've ran out of ideas.
Unlike with SQL Server, when you connect to a database using an ODBC connection, the parameter support is different. You cannot use named parameters and instead have to use the ? syntax.
In order to accommodate multiple values you can concatenate them into a single string and use a like statement to search them. However, this is inefficient. Another approach is to use a function to split the values into an in-line table.
In PostgreSQL you can use an expression like this:
inner join (select CAST(regexp_split_to_table(?, ',') AS int) as filter) as my on my.filter = key_column
Then in the dataset properties, under the parameters tab, use an expression like this to concatenate the values:
=Join(Parameters!Keys.Value, ",")
In other words, the report is concatenating the values into a comma-separated list. The database is splitting them into a table of integers then inner joining on the values.

Take first value of a column based on groupby of another

I'm struggling in finding the right way to achive this result: I would like to have the first value of a column related to a "group by" column.
Suppose that original table has 3 columns: a, b, c. I want to aggregate by the column b and have the first value of c.
I have tried to use the function below, but it doesn't work as I expect:
Aggr(nodistinct[c],[b])
Thanks for any help.
To achieve that you need to use FirstSortedValue in table:
FirstSortedValue(c,c)
Here is a link to example qliksense app (I put your data and saved it on my OneDrive):
https://1drv.ms/u/s!Am4ZTQ8qcLwRtACt1wAoUTdFZ6lt
If you need to implement it in your loading script you can use the same function.

ISNULL get the data from another column

If the email column is NULL, I want to have the phone number value in the PRIMARY_Contact column. I am using CASE expression, but could not do it properly.
You may be looking for COALESCE. It will return the first non-null value from a selection. It's actually just shorthand for CASE, but may be easier for you to implement.
In your example, perhaps that would look like this:
SELECT COALESCE(EMAIL,PRIMARY_CONTACT)
Check out https://msdn.microsoft.com/en-us/library/ms190349.aspx for more details.

Range table and IN not behaving properly

The program just selects everything if the carrid is ok even if it is not ok with the lt_spfli. And there aren't any entries with that carrid it gets runtime error. If I try with for all entries he just selects absolutely the entire SFLIGHT.
PARAMETERS: pa_airp TYPE S_FROMAIRP,
pa_carid TYPE S_CARR_ID.
DATA: lt_spfli TYPE RANGE OF SPFLI,
lt_sflight TYPE TABLE OF SFLIGHT.
SELECT CONNID FROM SPFLI
INTO TABLE lt_spfli
WHERE AIRPFROM = pa_airp.
SELECT * FROM SFLIGHT
INTO TABLE lt_sflight
WHERE CARRID = pa_carid AND CONNID in lt_spfli.
I just suppose, that you want every flight connection from a given airport...
Notice, that a RANGE structure has two more fields in front of the actual "compare value". So selecting directly into it will result in a very gibberish table.
Possible Solutions:
Selecting with RANGE
If you really want to use this temporary table, you can have a look at my answer here where I describe the way to fill RANGEs without any overhead. After this step, your current snippet will work the way to wanted it too. Just make sure, that it really has been filled or everything will be selected.
Selecting with FOR ALL ENTRIES
Before you use this variant you should make absolutely sure, that your specified data object is filled. Otherwise it will result in the same mess as the first solution. To do that, you could write:
* select connid
IF lt_spfli[] IS NOT INITIAL.
* select on SFLIGHT
ELSE.
* no result
ENDIF.
Selecting with JOIN
The "correct" approach in this case would be a JOIN like:
SELECT t~*
FROM spfli AS i
JOIN sflight AS t
ON t~carrid = #pa_carid
AND t~connid = i~connid
INTO TABLE #DATA(li_conns)
WHERE i~airpfrom = #pa_airp.
Use a FOR ALL ENTRIES instead of CONNID in lt_SPFLI.
As so:
SELECT *
FROM sflight
FOR ALL ENTRIES IN lt_spfli
WHERE carrid = pa_carid
AND connid = lt_spfli-connid
You are misunderstanding what a "Ranges Table" is. You fill it incorrectly.
This part of your code demonstrates the misunderstanding (with a little debug, you would see the erroneous contents immediately):
DATA: lt_spfli TYPE RANGE OF SPFLI.
SELECT CONNID FROM SPFLI INTO TABLE lt_spfli ...
A "Ranges Table" is an internal table with 4 components (SIGN, OPTION, LOW, HIGH), used in Open SQL to do complex selections on one database column (NB: it can also be used in several ABAP statements to test the value of an ABAP variable).
So, with your SQL statement, you only initialize the first component of the Ranges table, while you should transfer CONNID into the third component.
In "modern" Open SQL, you'd better do:
SELECT 'I' as SIGN, 'EQ' as OPTION, CONNID as LOW FROM SPFLI INTO TABLE #lt_spfli ...
For more information about Ranges Tables, you may refer to the answer here: What actually high and low means in a ranges table