How to replace underscore with a blank space with a regular expression in SQL - sql

Question

I'm trying to insert post codes into my database but getting rid of the underscores.
I have a table called FeedDataSetMapping that is used to map the fields before they get inserted:
INSERT INTO FeedDataSetMapping (
[source_field]
,[database_field]
,[template_id]
,[conversion_id]
,[order_id]
,[values_group]
,[direct_value]
,[value_regex]
,[condition_regex]
,[split_separator]
,[enclosing_character]
,[cumulative_field]
,[cumulative_format])
VALUES
('manufacturerId','manufacturer_Id',#template_id,0,0,null,null,null,null,null,null,null,null),
('dealership','leasing_broker_name',#template_id,0,0,null,null,null,null,null,null,null,null),
('manufacturersDealerId','supplier_ref',#template_id,0,0,null,null,19,null,null,null,null,null),
('address1','address1',#template_id,0,0,null,null,null,null,null,null,null,null),
('address2','address2',#template_id,0,0,null,null,null,null,null,null,null,null),
('postcode','post_code',#template_id,0,0,null,null,null,null,null,null,null,null),
('telephone','telephone',#template_id,0,0,null,null,null,null,null,null,null,null),
('fax','fax_number',#template_id,0,0,null,null,null,null,null,null,null,null),
('email','email',#template_id,0,0,null,null,null,null,null,null,null,null),
('website','web_address',#template_id,0,0,null,null,null,null,null,null,null,null),
('NewCarSales','service_mask',#template_id,0,0,null,1,null,'^(?!(?i:^0$|^n$|^no$|^f$|^false$|^$))',null,null,1,null),
('UsedCarSales','service_mask',#template_id,0,0,null,2,null,'^(?!(?i:^0$|^n$|^no$|^f$|^false$|^$))',null,null,1,null),
('Servicing','service_mask',#template_id,0,0,null,8,null,'^(?!(?i:^0$|^n$|^no$|^f$|^false$|^$))',null,null,1,null),
('Repairs','service_mask',#template_id,0,0,null,16,null,'^(?!(?i:^0$|^n$|^no$|^f$|^false$|^$))',null,null,1,null),
('Longitude','longitude',#template_id,0,0,null,null,null,null,null,null,null,null),
('Latitude','latitude',#template_id,0,0,null,null,null,null,null,null,null,null)
This already contains some condition regex that in case that this field contains some text it converts it to true or false respectively.
What I need is a condition_regex that gets rid of these underscores and replaces it with a blank space i.e: 'GDB_A45' to 'GDB A45'. I don't know much about regex so any idea would be greatly appreciated. Thanks in advance!

Answer 1

SQL Server does not have much of regular expression support, but in this case I don't think you need it. You can do a simple replace:
UPDATE mytable
SET mycolumn = REPLACE(mycolumn, '_', ' ')
WHERE mycolumn LIKE '%[_]%'
To do this while updating you can use INSERT ... SELECT instead of INSERT ... VALUES:
INSERT INTO mytable (mycolumn)
SELECT REPLACE('my data 1', '_', ' ') UNION
SELECT REPLACE('my data 2', '_', ' ') UNION
SELECT REPLACE('my_data_3', '_', ' ') UNION
...
There will be some maximum number of unions you can do, so you should split your inserts into batches with this method.
Or, you could define a trigger on the target table that will do the job for you:
CREATE TRIGGER mytrigger ON mytable
AFTER INSERT AS
BEGIN
UPDATE mytable
SET mytable.mycolumn = REPLACE(i.mycolumn, '_', ' ')
FROM mytable
INNER JOIN inserted i
ON i.id = mytable.id
AND i.mycolumn LIKE '%[_]%'
END
... where it is assumed your table has a primary key named id.

Answer 2

Well after been thinking a while I got to the conclusion that would be easier if I replace the underscore from the scraped data during the scraping (in the c# code) before I generate the XML file. That would avoid me a lot of headaches. Anyway thank you for your help guys ;)