2015 UK General Election using SQL Server

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Revision as of 07:40, 5 July 2017 by Andr3w (talk | contribs) (Go into sqlcmd or SSMS and create a table for the results)
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This tutorial assumes you have access to powershell and sqlcmd or Microsoft SQL Server Management Studio

Get to the powershell prompt and download the csv

Invoke-WebRequest http://researchbriefings.files.parliament.uk/documents/CBP-7979/hocl-ge2017-results-full.csv -OutFile ge2017.csv

Go into sqlcmd or SSMS and create a table for the results

Here you create a single flat table that can store all of the unnormalised data.

The first line of the CSV file contains the column headings (ons_id,ons_region_id,constituency_name,county_name,region_name,country_name,constituency_type,party_name,party_abbreviation,firstname,surname,gender,sitting_mp,former_mp,votes,share,change). We create a table with a column for each of these:

sqlcmd -S .\sqlexpress -E

We do not know the size of each column yet, too small and the import statement will give errors or warnings. It is best to be generous - memory is cheap.

The create table statement could be:

CREATE TABLE ge(
  ons_id VARCHAR(10),
  ons_region_id VARCHAR(10),
  constituency_name VARCHAR(50),
  county_name VARCHAR(50),
  region_name VARCHAR(50),
  country_name VARCHAR(50),
  constituency_type VARCHAR(10),
  party_name VARCHAR(50),
  party_abbreviation VARCHAR(50),
  firstname VARCHAR(50),
  surname VARCHAR(50),
  gender VARCHAR(6),
  sitting_mp VARCHAR(3),
  former_mp VARCHAR(3),
  votes INT,
  share FLOAT,
  change VARCHAR(20),
  PRIMARY KEY(ons_id,firstname,surname)
)

Attempt import the csv file into your flat table

You can import the data using this line (from SQLCMD or SQL Server Management Studio)

BULK INSERT ge FROM 'C:\db\ge2015.csv' WITH (FIELDTERMINATOR=',', ROWTERMINATOR='\n', FIRSTROW=2)
GO
  • Each line is ended with carriage return \n
  • The first row contains column headings not data so we start at row 2

You will most likely get error messages like this:

Msg 4863, Level 16, State 1, Server ME1C039-130368\SQLEXPRESS, Line 3
Bulk load data conversion error (truncation) for row 105, column 13 (sitting_mp).
Msg 4863, Level 16, State 1, Server ME1C039-130368\SQLEXPRESS, Line 3
Bulk load data conversion error (truncation) for row 106, column 12 (gender).
Msg 4863, Level 16, State 1, Server ME1C039-130368\SQLEXPRESS, Line 3
Bulk load data conversion error (truncation) for row 107, column 13 (sitting_mp).
...

Unfortunately BULK INSERT cannot deal with the CSV format so we need to preprocess the file. Some solutions:

  • Use Excel - you can load CSV and save as TXT
  • Use regular expressions: convert CSV to TXT
  • Use python
  • Find a converter online

With the conversion complete you can import the data - you will have too use the full path name and you may have permissions problems

BULK INSERT ge FROM 'c:\path\ge2017.txt' WITH (FIRSTROW=2)

Run some queries

Now let's look at some data. How many female candidates were there?

select count(1) from ge where gender='female';

Who stood in Edinburgh South?

select surname,votes from ge where constituency_name='Edinburgh South';

You can now move to the next stage: 2015 UK General Election Normalising Data