How to Populate Conditional Columns in MySQL Using CASE Statements?

Case Statement for Conditional Column Population in MySQL

In the context of the 'tbl_transaction' table with columns 'id,' 'action_type,' 'action_heading,' and 'action_amount,' it is possible to generate desired result columns 'Income Amt' and 'Expense Amt' using a SQL query that populates these columns conditionally.

The query leverages the CASE statement's ability to evaluate the value of 'action_type' and assign the corresponding 'action_amount' to either the 'income_amt' or 'expense_amt' column.

SELECT
    id,
    action_heading,
    CASE
        WHEN action_type = 'Income' THEN action_amount
        ELSE NULL
    END AS income_amt,
    CASE
        WHEN action_type = 'Expense' THEN action_amount
        ELSE NULL
    END AS expense_amt
FROM tbl_transaction;

The result will be columns 'income_amt' and 'expense_amt' correctly populated with amounts based on the 'Income' or 'Expense' value in 'action_type.'

ID        Heading         Income Amt       Expense Amt
1         ABC             1000             -
2         XYZ             -                2000

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