Joseph,
I hope this to be a simple question. I have need to simply read the first
row in a given table. Right now, I have some legacy code that selects all
rows in a table just to see if the first row has a certain value.
Your problem is conceptual: in SQL, there is no first row.
If you want to just pick a single row at random, do
SELECT * FROM table LIMIT 1;
Or if you have a primary key id, you could for example return the row with the
lowest id:
SELECT * FROM table ORDER BY id LIMIT 1;
The code is seeking to see if an update has been run or not. A hypothetical
scenario would be: has an update been run to populate data into a new
column in a table. Neither the data nor any of the rows are consistently
known. So the test selects all rows, tests the first row and then ends if
the column has a value.
I'd write an ON UPDATE trigger, personally, to fire and write data somewhere
else whenever the table is updated. Much more reliable
--
Josh Berkus
Aglio Database Solutions
San Francisco
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TIP 8: explain analyze is your friend
