Efficient SQL Query for Summarizing Transaction Data
Extracting data based on multiple criteria is a common task in database management. Imagine a "transactions" table containing account_id, budget_id, points, and transaction type (allocation or issue). The challenge is to efficiently calculate the total points for each budget_id, separated by allocation and issue types.
A concise SQL query can elegantly solve this problem:
<code class="language-sql">SELECT budget_id, SUM(CASE WHEN type = 'allocation' THEN points ELSE 0 END) AS allocated, SUM(CASE WHEN type = 'issue' THEN points ELSE 0 END) AS issued FROM transactions GROUP BY budget_id;</code>
This query leverages the CASE
statement within the SUM()
function. The CASE WHEN type = 'allocation' THEN points ELSE 0 END
expression checks the transaction type. If it's 'allocation', the corresponding points
value is summed; otherwise, 0 is added. This conditional summation is repeated for 'issue' type transactions.
Grouping the results by budget_id
provides a summary showing the allocated and issued points for each budget. The output clearly presents a consolidated view of the transaction data, facilitating analysis and reporting.
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