Pivot In SQL

How can you transform rows into columns in a SQL table?

The PIVOT function in SQL is a powerful tool for transforming rows into columns. It's particularly useful for summarizing data in a way that's easier to analyze and present. It's often used to reshape data for reporting and dashboards.

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Description

The PIVOT function in SQL is used to rotate rows into columns. Imagine you have a table with multiple rows of data grouped by a category, and you want to see the values for each category in separate columns. PIVOT makes this transformation straightforward. It's especially helpful when you need to aggregate data based on different categories and display the results in a tabular format suitable for reporting or analysis. For example, you might have sales data for different products in various regions, and you want to see the total sales for each product in each region. PIVOT can efficiently achieve this. It's important to understand that the values you want to pivot into columns must be known beforehand, as the function requires explicit column names for the transformation. This contrasts with other functions that might dynamically generate columns based on data.

Why Pivot In SQL is important

PIVOT is crucial for transforming data into a more usable format for reporting and analysis. It allows for a more concise and insightful presentation of aggregated data, making it easier to identify trends and patterns.

Example Usage


CREATE TABLE SalesData (
    Region VARCHAR(20),
    Product VARCHAR(20),
    Sales INT
);

INSERT INTO SalesData (Region, Product, Sales)
VALUES
('North', 'A', 100),
('North', 'B', 150),
('South', 'A', 120),
('South', 'B', 180),
('East', 'A', 140),
('East', 'B', 200);

SELECT *
FROM
(
    SELECT Region, Product, Sales
    FROM SalesData
) AS SourceTable
PIVOT (
    SUM(Sales)
    FOR Product IN ([A], [B])
) AS PivotTable;

Common Mistakes

Forgetting to specify the aggregate function (e.g., SUM, AVG).
Incorrectly specifying the columns to pivot.
Not understanding that the values to pivot into columns must be known in advance.
Using the wrong syntax for the PIVOT clause.

Pivot In SQL

How can you transform rows into columns in a SQL table?

Description

Why Pivot In SQL is important

Example Usage

Common Mistakes

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