Pivot / Transform rows from one column into multiple columns with R in SqlServer

Let’s say we have a table  [CurrencyValues] with the following datas

CurrencyID CurrencyValue ValueDate
CAD 2.9929 9/27/2016 0:00
EUR 4.4495 9/27/2016 0:00
GBP 5.1205 9/27/2016 0:00
USD 3.9567 9/27/2016 0:00
CAD 3.0006 9/26/2016 0:00
EUR 4.4504 9/26/2016 0:00
GBP 5.1213 9/26/2016 0:00
USD 3.9589 9/26/2016 0:00
CAD 3.0397 9/23/2016 0:00
EUR 4.447 9/23/2016 0:00

We want to transform the CurrencyID into columns( i.e. a column with CAD, other with EUR, other with GBP and so on) .

We can utilize R from SqlServer (https://msdn.microsoft.com/en-us/library/mt604885.aspx )

We have 2 prerequisites;

1. R is running inside SqlServer

2. The library tidyR is downloaded

( see the final of this post to verify)

Then we execute the following script:

 

 

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execute sp_execute_exterhttp://msprogrammer.serviciipeweb.ro/wp-admin/widgets.phpnal_script
@language = N'R'
, @script = N'
library(tidyr);
model<-spread(InputDataSet, CurrencyID, CurrencyValue);
OutputDataSet <- model'
, @input_data_1 = N'select   CurrencyID, CurrencyValue, ValueDate  from CurrencyValues '
 
WITH RESULT SETS undefined

The output is this:

(No column name) (No column name) (No column name) (No column name) (No column name)
00:00.0 3.0397 4.447 NULL NULL
00:00.0 3.0006 4.4504 5.1213 3.9589
00:00.0 2.9929 4.4495 5.1205 3.9567

The problem is that we have columns without names (spread returns data frame columns names, but SqlServer does not … yet, I hope)

So we add the column names:

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execute sp_execute_external_script
@language = N'R'
, @script = N'
library(tidyr);
model<-spread(InputDataSet, CurrencyID, CurrencyValue);
cols<-paste(colnames(model),collapse = ",");
model<-cbind(ColumnNames = cols, model);
 
OutputDataSet <- model'
, @input_data_1 = N'select   CurrencyID, CurrencyValue, ValueDate  from CurrencyValues '
 
WITH RESULT SETS undefined

and  the result is slightly better:

(No column name) (No column name) (No column name) (No column name) (No column name) (No column name)
ValueDate,CAD,EUR,GBP,USD 00:00.0 3.0397 4.447 NULL NULL
ValueDate,CAD,EUR,GBP,USD 00:00.0 3.0006 4.4504 5.1213 3.9589
ValueDate,CAD,EUR,GBP,USD 00:00.0 2.9929 4.4495 5.1205 3.9567

What I want? Sql Server should return column names in data frame by default …

And that is all  –  execute sp_execute_external_script have the possibility of parameters, so you can make general.

End!

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Note 1: R is running inside SqlServer

Verify

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exec sp_execute_external_script 
  @language =N'R',   
  @script=N'OutputDataSet<-InputDataSet',     
  @input_data_1 =N'select 1 as hello'   
  with result sets (([hello] int not null));   
go

If it gives error , then follow https://msdn.microsoft.com/en-us/library/mt696069.aspx  – basic is

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Exec sp_configure  'external scripts enabled', 1 
Reconfigure  with  override

and restart SqlServer

 

Note 2: Installing package tidyr

Follow https://msdn.microsoft.com/en-us/library/mt591989.aspx : basic is starting R with admin rights and executing

lib.SQL <- "C:\\Program Files\\Microsoft SQL Server\\MSSQL13.MSSQLSERVER\\R_SERVICES\\library"
install.packages("tidyr", lib = lib.SQL)

and that will be all ( ok, you may find some additional libraries to install)