I have a table with many fields and additionally several boolean fields (ex: BField1, BField2, BField3 etc.).
I need to make a Select Query, which will select all fields except for boolean ones, and a new virtual field (ex: FirstTrueBool) whose value will equal to the name of the first TRUE Boolean Field.
For ex: Say I have BField1 = False, BField2 = True, BField3 = true, BField4=false, in that case SQL Query should set [FirstTrueBool] to "BField2". Is that possible?
Thank you in advance.
P.S. I use Microsoft Access (MDB) Database and Jet Engine.
If you want to keep the current architecture (mixed 'x' non-null status and 'y' non-status fields) you have (AFAIS now) only the option to use IIF:
Select MyNonStatusField1, /* other non-status fields here */
IIF([BField1], "BField1",
IIF([BField2], "BField2",
...
IIF([BFieldLast], "BFieldLast", "#No Flag#")
))))) -- put as many parenthesis as it needs to close the imbricated IIFs
From
MyTable
Of course you can add any Where clause you like.
EDIT:
Alternatively you can use the following trick:
Set the fields to null when the flag is false and put the order number (iow, "1" for BField1, "2" for BField2 etc.) when the flag is true. Be sure that the status fields are strings (ie. Varchar(2) or, better, Char(2) in SQL terminology)
Then you can use the COALESCE function in order to return the first non-value from the status fields which will be the index number as string. Then you can add in front of this string any text you like (for example "BField"). Then you will end with something like:
Select "BField" || Coalesce(BField1, BField2, BField3, BField4) /*etc. (add as many fields you like) */
From MyTable
Much clearer IMHO.
HTH
You would be better using a single 'int' column as a bitset (provided you have up to 32 columns) to represent the columns.
e.g. see SQL Server: Updating Integer Status Columns (it's sql server, but the same technique applies equally well to MS Access)
Related
I have a list of data with a title column (among many other columns) and I have a Power BI parameter that has, for example, a value of "a,b,c". What I want to do is loop through the parameter's values and remove any rows that begin with those characters.
For example:
Title
a
b
c
d
Should become
Title
d
This comma separated list could have one value or it could have twenty. I know that I can turn the parameter into a list by using
parameterList = Text.Split(<parameter-name>,",")
but then I am unsure how to continue to use that to filter on. For one value I would just use
#"Filtered Rows" = Table.SelectRows(#"Table", each Text.StartsWith([key], <value-to-filter-on>))
but that only allows one value.
EDIT: I may have worded my original question poorly. The comma separated values in the parameterList can be any number of characters (e.g.: a,abcd,foo,bar) and I want to see if the value in [key] starts with that string of characters.
Try using List.Contains to check whether the starting character is in the parameter list.
each List.Contains(parameterList, Text.Start([key], 1)
Edit: Since you've changed the requirement, try this:
Table.SelectRows(
#"Table",
(C) => not List.AnyTrue(
List.Transform(
parameterList,
each Text.StartsWith(C[key], _)
)
)
)
For each row, this transforms the parameterList into a list of true/false values by checking if the current key starts with each text string in the list. If any are true, then List.AnyTrue returns true and we choose not to select that row.
Since you want to filter out all the values from the parameter, you can use something like:
= Table.SelectRows(#"Changed Type", each List.Contains(Parameter1,Text.Start([Title],1))=false)
Another way to do this would be to create a custom column in the table, which has the first character of title:
= Table.AddColumn(#"Changed Type", "FirstChar", each Text.Start([Title],1))
and then use this field in the filter step:
= Table.SelectRows(#"Added Custom", each List.Contains(Parameter1,[FirstChar])=false)
I tested this with a small sample set and it seems to be running fine. You can test both and see if it helps with the performance. If you are still facing performance issues, it would probably be easier if you can share the pbix file.
This seems to work fairly well:
= List.Select(Source[Title], each Text.Contains(Parameter1,Text.Start(_,1))=false)
Replace Source with the name of your table and Parameter1 with the name of your Parameter.
I'm using SPSS modeler and I have a variable that the software recognizes as numeric. So the missing values are $null$. I want that the missing values of the variable are selectionable with '', as character.
So I would: or trasform the format of the variable from numeric to character or change only the missing values from $null$ to ''.
How can I fix?
thanks in advance
The best way to select null values in a numeric field is to use the #NULL() function from the Blanks and Null section of the Expression Builder.
For example, if you wanted to keep only the null values so that you could inspect them, you might use a Select node. Leave the radio button set as Include. Press the Expression Builder (calculator) button. Change the filter in the drop menu on the left side from General Functions to show Blanks and Null (press B 2 or 3 times). Double-click on #NULL(ITEM). Go to the right side and double-click on your numeric field name. Put a Table node at the end and run it.
Using Select #NULL in IBM SPSS Modeler
Another way to view just the null rows is to enter the #NULL(varname) function into the "Highlight records where" section of the Table dialog box.
"Highlight records where" dialog
When you run the table, any row that is true for this condition will be shown in red.
If you really need the variable to be a string, then use a Compute node to create a copy of this field under a new name and use the to_string() function in the Conversion section of the Expression Builder to change the type of the variable. Now you will be able to use the the Select node to grab "" as the missing value. Or you could use the Filler node to replace the column, but then you would not be able to compare before and after.
The dialog examples shown in this answer use this sample stream that is installed with your IBM SPSS Modeler software:
C:\Program Files\IBM\SPSS\Modeler\18.0\Demos\streams\featureselection.str
The easiest way to do it it's using the Fill node with the configurations:
A) FIELD
B) Condition = #NULL(#FIELD)
C) Replace by = ' '
This node will replace all $null$ for ' ' at the same variable chosen in option a.
I don't think you can customize how you visualize $nulls. (I know it's possible in SQL db though)
So I'd suggest that you work with the numbers and when you want to visualize or export the results, then turn the field to a string one then replace nulls:
Filled node > to_string(#FIELD)
Filler node > blank and nulls > #FIELD = ''
I'm writing a delphi(7 ver) application and in some place I want to execute parameterized queries (for BDE and Paradox) which will be loaded at runtime into a TQuery by the user. These queries will be stored in text files (one text file for one query). The application then, will construct for any parameter of the query, one input control (Tedit) in order to be able to accept values by the user. Also there will be a button for the execution of query. My question is how can I recognize the datatype of the query's parameter? Is there a way to get this type without of cause to be included in some way in the text file containing the query?
Create a second query from the first, but modify its where clause to ensure no rows.
SELECT * FROM MYTABLE WHERE PKFIELD IS NULL
Name your parameters so that you can establish their datatypes from the fieldtypes of this second query.
I realise this only works for relatively simple cases, but it should get you some of the way.
the advantage of using a parameter is that you don't need to know its data type.
Use the string value from the tedit
"select * from mytable where myfield = :param1"
"parambyname('param1').asstring := edit1.text"
I've made this with MySQL database. you must define some parameters, Exemple:
SELECT * FROM MyTable WHERE MyField=[ANNEE];
in this case, i have an other table, called balise, that look like this
"ID" "BALISE" "CAPTION" "DEFAULT_VALUE" "CNDT" "COMPOSANT"
"1" "ANNEE" "Année" "2014" "Properties.MaxValue=2014||Properties.MinValue=2007" 1;
in runtime, this mean that:
Make in my Panel, a TLablel that have caption Année
Make in the same line an other component type 1 (That mean in my case TcxSpinEdit), this component have défault value 2014, have Two properties Max Value=2014 and Min Value=2007, (I use RTTI to modifie this value of parameters, in Delphi ver7, use TypeInfo).
An Other Button with function called Actualise, this function have Original query, must browse an array of TBalise that i have created, take the value (In my case, take TcxSpinEdit(MyObject).Value), and replace it in the copy of my query (AnsiReplaceStr(Requete, '[ANNEE]', MyValue)), so i have the final query to execute it.
I have module in complete projet, worked with this methode, and it workk fine.
I have a complex query that contains more than one place where the same primary key value must be substituted. It looks like this:
select Foo.Id,
Foo.BearBaitId,
Foo.LinkType,
Foo.BugId,
Foo.GooNum,
Foo.WorkOrderId,
(case when Goo.ZenID is null or Goo.ZenID=0 then
IsNull(dbo.EmptyToNull(Bar.FanName),dbo.EmptyToNull(Bar.BazName))+' '+Bar.Strength else
'#'+BarZen.Description end) as Description,
Foo.Init,
Foo.DateCreated,
Foo.DateChanged,
Bug.LastName,
Bug.FirstName,
Goo.BarID,
(case when Goo.ZenID is null or Goo.ZenID=0 then
IsNull(dbo.EmptyToNull(Bar.BazName),dbo.EmptyToNull(Bar.FanName))+' '+Bar.Strength else
'#'+BarZen.Description end) as BazName,
GooTracking.Status as GooTrackingStatus
from
Foo
inner join Bug on (Foo.BugId=Bug.Id)
inner join Goo on (Foo.GooNum=Goo.GooNum)
left join Bar on (Bar.Id=Goo.BarID)
left join BarZen on (Goo.ZenID=BarZen.ID)
inner join GooTracking on(Goo.GooNum=GooTracking.GooNum )
where (BearBaitId = :aBaitid)
UNION
select Foo.Id,
Foo.BearBaitId,
Foo.LinkType,
Foo.BugId,
Foo.GooNum,
Foo.WorkOrderId,
Foo.Description,
Foo.Init,
Foo.DateCreated,
Foo.DateChanged,
Bug.LastName,
Bug.FirstName,
0,
NULL,
0
from Foo
inner join Bug on (Foo.BugId=Bug.Id)
where (LinkType=0) and (BearBaitId= :aBaitid )
order by BearBaitId,LinkType desc, GooNum
When I try to use an integer parameter on this non-trivial query, it seems impossible to me. I get this error:
Error
Incorrect syntax near ':'.
The query works fine if I take out the :aBaitid and substitute a literal 1.
Is there something else I can do to this query above? When I test with simple tests like this:
select * from foo where id = :anid
These simple cases work fine. The component is TADOQuery, and it works fine until you add any :parameters to the SQL string.
Update: when I use the following code at runtime, the parameter substitutions are actually done (some glitch in the ADO components is worked around) and a different error surfaces:
adoFooContentQuery.Parameters.FindParam('aBaitId').Value := 1;
adoFooContentQuery.Active := true;
Now the error changes to:
Incorrect syntax near the keyword 'inner''.
Note again, that this error goes away if I simply stop using the parameter substitution feature.
Update2: The accepted answer suggests I have to find two different copies of the parameter with the same name, which bothered me so I reworked the query like this:
DECLARE #aVar int;
SET #aVar = :aBaitid;
SELECT ....(long query here)
Then I used #aVar throughout the script where needed, to avoid the repeated use of :aBaitId. (If the number of times the parameter value is used changes, I don't want to have to find all parameters matching a name, and replace them).
I suppose a helper-function like this would be fine too: SetAllParamsNamed(aQuery:TAdoQuery; aName:String;aValue:Variant)
FindParam only finds one parameter, while you have two with the same name. Delphi dataset adds each parameter as a separate one to its collection of parameters.
It should work if you loop through all parameters, check if the name matches, and set the value of each one that matches, although I normally choose to give each same parameter a follow-up number to distingish between them.
Say I have a model called Transaction which has a :transaction_code attribute.
I want that attribute to be automatically filled with a sequence number which may differ from id (e.g. Transaction with id=1 could have transaction_code=1000).
I have tried to create a sequence on postgres and then making the default value for the transaction_code column the nextval of that sequence.
The thing is, if I do not assign any value to #transaction.transaction_code on RoR, when I issue a #transaction.save on RoR, it tries to do the following SQL:
INSERT INTO transactions (transaction_code) VALUES (NULL);
What this does is create a new row on the Transactions table, with transaction_code as NULL, instead of calculating the nextval of the sequence and inserting it on the corresponding column. Thus, as I found out, if you specify NULL to postgres, it assumes you really want to insert NULL into that column, regardless of it having a default value (I'm coming from ORACLE which has a different behavior).
I'm open to any solution on this, either if it is done on the database or on RoR:
either there is a way to exclude attributes from ActiveRecord's
save
or there is a way to change a column's value before insert with a trigger
or there is a way to generate these sequence numbers within RoR
or any other way, as long as it works :-)
Thanks in advance.
For the moment, you might be stuck fetching and assigning the sequence in your ROR model like this:
before_create :set_transaction_code_sequence
def set_transaction_code_sequence
self.transaction_code = self.class.connection.select_value("SELECT nextval('transaction_code_seq')")
end
I'm not particularily fond of this solution, since I'd like to see this corrected in AR directly... but it does do the trick.
If you want to insert the default value in to a column in an INSERT statement, you can use the keyword DEFAULT - no quotes:
INSERT INTO mytable (col1, col2) VALUES (105, DEFAULT);
Or you could spell out the default, nextval(...) in your case. See the manual here.
A trigger for that case is simple. That's actually what I would recommend if you want to make sure that only numbers from your sequence are entered, no matter what.
CREATE OR REPLACE FUNCTION trg_myseq()
RETURNS trigger AS
$BODY$
BEGIN
NEW.mycol := nextval('my_seq');
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;
CREATE TRIGGER myseq
BEFORE INSERT
ON mytable
FOR EACH ROW
EXECUTE PROCEDURE trg_myseq();
On a side note:
If you want to assign your own (non-sequential) numbers as 'sequence', I have written a solution for that in an answer a couple of days ago:
How to specify list of values for a postgresql sequence
I was still experiencing this issue with Rails7 - I could see that Rails was generating a NULL in the insert, but changing the column from integer to bigint solved it. - Rails then does not supply a value for my sequenced column and the DEFAULT nextval('number_seq') is used.