How to use unpivot in oracle
The UNPIVOT operator converts row data in Oracle into column data for easier analysis and querying. It converts a data set containing multiple rows and columns into a new data set with an ID column representing the original row and a value column containing the values from the original column. The UNPIVOT syntax is: SELECT * FROM UNPIVOT(table_name) AS unpivoted_table[WHERE pivot_condition]. Benefits include simplified queries, improved performance, and support for pivoting. For example, you can convert sales quarter data into columns to easily analyze sales by product and quarter.
UNPIVOT Usage in Oracle
What is UNPIVOT?
UNPIVOT is an Oracle operator used to convert row data to column data. It transforms a multi-row, multi-column data set into a new data set with two columns: an ID column (representing the original rows) and a value column (containing the values from the original columns).
UNPIVOT Usage
UNPIVOT syntax is as follows:
<code>SELECT * FROM UNPIVOT(table_name) [AS unpivoted_table] [FOR column_name IN (column_list)] [WHERE pivot_condition]</code>
Among them:
-
table_name
is The name of the dataset to convert. -
column_name
is the name of the original column to be converted to a column. -
column_list
is the list of raw columns to be converted to columns. -
pivot_condition
is an optional condition used to filter the data to be converted into columns.
Example
Suppose there is a data set named sales
that contains the following columns:
product_id
product_name
sales_q1
sales_q2
sales_q3
sales_q4
To convert sales quarter data into columns, you can use the following UNPIVOT query:
<code>SELECT * FROM UNPIVOT(sales) AS unpivoted_sales FOR sales_quarter IN (sales_q1, sales_q2, sales_q3, sales_q4)</code>
The resulting dataset will look like this:
product_id | product_name | sales_quarter | sales_value |
---|---|---|---|
1 | Product A | Q1 | 100 |
1 | Product A | Q2 | 200 |
1 | Product A | Q3 | 300 |
1 | Product A | #Q4 | 400 |
2 | Product B | Q1 | 500 |
2 | Product B | Q2 | 600 |
2 | Product B | Q3 | 700 |
2 | Product B | Q4 | 800 |
## Advantages of UNPIVOT
Using UNPIVOT has the following advantages:- Convert row data into column data that is easier to analyze.
- Simplify query and report design.
- Improve the performance of data aggregation and pivot tables.
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