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I would like to retrieve the top 1 value of result set of query which is connected using Union
SELECT TOP 1 * FROM
(
SELECT paused_time as end_time
FROM production_time
WHERE created_time = curdate()
UNION
SELECT resumed_time as end_time
FROM pause_timer
WHERE created_time = curdate()
UNION
SELECT end_time as end_time
FROM timer_idle
WHERE created_time = curdate()
) as end_time
ORDER BY end_time DESC
But could not get the expected result.
265
The SQL SELECT TOP Clause The SELECT TOP clause is used to specify the number of records to return. The SELECT TOP clause is useful on large tables with thousands of records. Returning a large number of records can impact performance.
The statement 'select 1' from any table name means that it returns only 1. For example, If any table has 4 records then it will return 1 four times.
Here's the syntax to select top N rows in MySQL. In the above statement, we list the columns column1, column2, … that you want to select in your query. Also, you need to specify LIMIT n after the table name, where n is the number of rows you want to select. The above query will select top n records in your table.
There is no TOP keyword in MySQL as far as I am aware. What you require is Limit:
SELECT * FROM
(
SELECT paused_time as end_time FROM production_time WHERE created_time = curdate()
UNION
SELECT resumed_time as end_time FROM pause_timer WHERE created_time = curdate()
UNION
SELECT end_time as end_time FROM timer_idle WHERE created_time = curdate()
) as end_time
ORDER BY end_time DESC
LIMIT 1
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