precursive

Sorry, above vbscript should have read (squigglies got mistranslated):

Set fso = CreateObject("Scripting.FileSystemObject")
Set listFile = fso.OpenTextFile("products.txt")
Wscript.Echo "INSERT INTO 'wp_yhdgsp_postmeta' ('post_id', 'meta_key', 'meta_value') VALUES"
do while not listFile.AtEndOfStream
    pName =  listFile.ReadLine()
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_1', '12'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_text_info', 'Buy Twelve or More, Save 20% !'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_enabled', 'yes'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_1', '20'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_2', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_2', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_3', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_3', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_4', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_4', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_5', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_5', ''),"
loop

So I ended up getting this done for a couple of hundred products, though I’d hardly call my process ‘reproducible’ — the SQL insert query I used is as follows:

INSERT INTO 'wp_yhdgsp_postmeta' ('post_id','meta_key','meta_value') VALUES
(28, '_bulkdiscount_enabled', 'yes'),
(28, '_bulkdiscount_text_info', 'Buy Twelve or More, Save 20% !'),
(28, '_bulkdiscount_quantity_1', '12'),
(28, '_bulkdiscount_discount_1', '20'),
(28, '_bulkdiscount_quantity_2', ''),
(28, '_bulkdiscount_discount_2', ''),
(28, '_bulkdiscount_quantity_3', ''),
(28, '_bulkdiscount_discount_3', ''),
(28, '_bulkdiscount_quantity_4', ''),
(28, '_bulkdiscount_discount_4', ''),
(28, '_bulkdiscount_quantity_5', ''),
(28, '_bulkdiscount_discount_5', '')

Note that the query above references post_id 28… so as not to have to manually code this out for hundreds of products, actually first wrote a script which retrieved from the posts table all IDs where post_type equaled product, exported that to a text file (products.txt) so that products.txt looked like…

22
23
24
26
28
30
77

Then used a vbscript:

Set fso = CreateObject("Scripting.FileSystemObject")
Set listFile = fso.OpenTextFile("products.txt")
Wscript.Echo "INSERT INTO <code>wp_yhdgsp_postmeta</code> (<code>post_id</code>, <code>meta_key</code>, <code>meta_value</code>) VALUES"
do while not listFile.AtEndOfStream
    pName =  listFile.ReadLine()
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_1', '12'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_text_info', 'Buy Twelve or More, Save 20% !'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_enabled', 'yes'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_1', '20'),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_2', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_2', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_3', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_3', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_4', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_4', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_quantity_5', ''),"
	Wscript.Echo "(" + pName + ", '_bulkdiscount_discount_5', ''),"
loop

… executed with:

cscript.exe createSQLStatements.vbs > output.txt

… then finally opened that output.txt file and removed the last comma… and imported the contents of that file into the database.

Will be working on making this more reproducible for my client, wish I knew how to contribute to/extend a plugin.

Good luck!
Nick