A Join in Many Languages

SELECT P.Name AS ProductName, PSC.Name AS SubcategoryName
FROM Product AS P
LEFT JOIN ProductSubcategory AS PS
ON P.ProductSubcategoryID = PS.ProductSubcategoryID

import csv
product = []
with open("Product.csv") as fh:
	reader = csv.DictReader(fh,delimiter="\t")
	for line in reader:
		product.append(line)
productsubcategory = []
with open("ProductSubcategory.csv") as fh:
	reader = csv.DictReader(fh,delimiter="\t")
	for line in reader:
		productsubcategory.append(line)
results = []
for prod in product:
	prodname = prod.get("Name")
	subcategoryid = prod.get("ProductSubcategoryID")
	subcatname = None
	if subcategoryID != '':
		for subcat in productsubcategory:
			if subcategoryid == subcat.get("ProductSubCategory"):
				subcatname = subcat.get("Name")
				break
	results.append({"ProductName":prodname,"SubcategoryName":subcatname})
print results

product<-read.csv('Product.csv',sep="\t",header=TRUE)
productsubcategory<-read.csv('ProductSubcategory.csv',sep="\t",header=TRUE)
results.full<-merge(product,productsubcategory,by.x="ProductSubcategoryID",by.y="ProductSubcategoryID",all.x=TRUE)
results.full.subset<-subset(results.full,select=c("Name.x","Name.y"))
names(results.full.subset)<-c("ProductName","SubcategoryName")
print(results.full.subset)

$product = import-csv "Product.csv" -Delimiter "`t"
$productsubcategory = import-csv "ProductSubcategory.csv" -Delimiter "`t"
$product | foreach-object {
    $prod = $_
    if ($prod.ProductSubcategoryID -ne '') {
        $productsubcategory | 
            where-object {$_.ProductSubcategoryID -eq $prod.ProductSubcategoryID} |
            select-object @{Name='ProductName';Expression={$prod.name}},@{Name='SubcategoryName';Expression={$_.name}}
    } else {
        $prod | select-object @{Name='ProductName';Expression={$_.name}},@{Name='SubcategoryName';Expression={$null}}
    }
}

--For this example, we will treat the file as if the headers are removed and the newline character is converted to \n rather than \r\n
product = LOAD 'Product.csv' USING PigStorage('\t');
subcategory = LOAD 'ProductSubCategory.csv' USING PigStorage('\t');
product_project = FOREACH product GENERATE $1 AS ProductName, $18 AS ProductSubcategoryID;
subcategory_project = FOREACH subcategory GENERATE $0 AS ProductSubcategoryID,$2 AS SubcategoryName;
joined = JOIN product_project BY ProductSubcategoryID LEFT, subcategory_project BY ProductSubcategoryID;
joined_project = FOREACH joined GENERATE ProductName,SubcategoryName;
--Executing the below line will explain the logical execution plan to get to the final results
--EXPLAIN joined_project;
DUMP joined_project;