is_active ))) as categories from product p left join product_category pc on pc. name, jsonb_build_object ( 'active', pc.
name as product, jsonb_agg ( jsonb_build_object ( c. When we return this information as JSON this is very easy: Adding that column to the “traditional” PIVOT or filtered aggregation query would massively blow up the code. The product_category table contains a flag if the assignment to the category is currently active. But much more importantly: it enables us to easily extend what we return. The value can directly be used by a HTML/JavaScript frontend. JSON has some advantages: it’s a well defined format and we don’t need to think about what characters to escape. Why JSON? We could also easily use string_agg() to get a comma separated list of categories.
Pivot in oracle 10g tv#
+-ġ32cm TV Set | ġ52cm TV Set | ĥ5cm Monitor | ħ0cm Monitor | The output for the above (Postgres) query would be: product | categories Without seeing the output, it is obvious that this query doesn’t need to be changed when more categories are added. name ) as categories from product p left join product_category pc on pc. The easiest way is to return the categories as a single JSON array: on a web page, it is a lot easier to return the categories as a JSON value that can directly be used by the frontend. a spreadsheet program like LibreOffice Calc.īut if that data is intended to be displayed e.g. The above output is very usefull if the data should be imported into e.g. But just like conditional aggregation, it suffers from the same problem: the query needs to be changed each time a new category is added. Postgres also offers a crosstab function to do this. It is pretty obvious that this gets really cumbersome if a new category is added and it also doesn’t scale very well. Swiss Army Knife | | | Tools | Outdoor Equipment | | Standard Laptop | Electronics | | | | | Laptops High End Laptop | Electronics | | | | | Laptops +-+-+-+-+-+-ġ32cm TV Set | Electronics | TV Sets | | | Displays |ġ52cm TV Set | Electronics | TV Sets | | | Displays |ĥ5cm Monitor | Electronics | | | | Displays |ħ0cm Monitor | Electronics | | | | Displays | name īased on the sample data the output would look like this: product | category_1 | category_2 | category_3 | category_4 | category_5 | category_6 name = 'Laptops' ) as category_6 from product p left join product_category pc on pc.
name = 'Displays' ) as category_5, max ( c. name = 'Outdoor Equipment' ) as category_4, max ( c. name = 'Tools' ) as category_3, max ( c. name = 'TV Sets' ) as category_2, max ( c. name = 'Electronics' ) as category_1, max ( c. Suppose you have a list of preferred states and you want to select the rows for those states only.Select p. In addition to the ANY clause, you can write a subquery. You can use the output in any XML parser to produce more useful output. Each value is represented as a name-value element pair.
Pivot in oracle 10g code#
Here I will use a slightly modified form of his original code to generate vowels of the English alphabet:Īs you can see, the column STATE_CODE_XML is XMLTYPE, where the root element is. Oracle ACE Director Lucas Jellema of Amis Technologies has shown how you can generate rows of specific data for testing purposes. Some of the very interesting uses of unpivot go beyond the usual powerful data manipulation such as the example shown earlier. So unpivot is not for undoing what pivot did, a fact you should carefully consider before creating a pivoted table and then dropping the original one. Instead the crosstab report was displayed in a different way for you to load into a relational table. Later you used unpivot on the table CUST_MATRIX but that didn't get back the details of the original table CUSTOMERS. For instance, in the above example, you created a new table, CUST_MATRIX, using a pivotnoperation on the table CUSTOMERS. Unpivot may be the opposite action of pivot but don't assume that former can reverse what latter has done. As you specified state_counts, that is the name of the new column created in the resultant output. Purchase Frequency New York Conn New Jersey Florida MissouriĪs the column "New York" suddenly became a value in a row, how would you show the value 33048, under which column? That question is answered by the clause just above the for clause inside the unpivot operator in the above query.
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