Compare last values of two columns in SQL table to Create Grafana Alerts Condition

Question

I have columns such as 'LTP' = 10, 'lowerbound' = 20, 'Timestamp' in a SQL table. If last value of 'LTP' < 'lowerbound', then alert should get triggered in Grafana.

In Grafana: how to create an alert by comparing values of columns in SQL table?

Answer 1

SQL Query Working in Grafana using CASE to Check multiple conditions in Single Grafana Alert:

SELECT 
    CASE
        WHEN difference < lower_range THEN 1
        WHEN difference > upper_range THEN 0
        ELSE 2
    END AS condition_result
FROM <db name>.<tl name>
ORDER BY DATE DESC
LIMIT 1;

IF We want to sum up the value of two conditions based on last two rows, the sql query for that as below:

SELECT SUM(condition_result) AS total_sum
FROM (
    SELECT 
        CASE
            WHEN final_lowerband < Close THEN 1
            WHEN final_upperband > Close THEN 2
            ELSE 0
        END AS condition_result,
        ROW_NUMBER() OVER (ORDER BY DATE DESC) AS row_num
    FROM <db name>.<table name>
    ORDER BY DATE DESC
    LIMIT 2
) AS ranked_data;