sql sum() function · csH sql walk routes

csH sql walk routes

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basic aggregate functions

Introducing: sum()

This simple query will display the time spent out on all all the walks.

select minutestaken from walk

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Think about this requirement:

Some people have been out on all the walks; how long did they spend walking all together?

A calculation which adds up the all the minutes taken column value in every row is needed.

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Here is how the SQL sum() function could be used to produce the total.

select sum(minutestaken) as "walking time total" from walk

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take care not to confuse SUM and COUNT ..

select count(minutestaken) as "walking time total" from walk

.. this query would simply return 8, can you explain why?

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save your working code in application express

Try a simple version first, like: display all rows and columns. Then introduce sum(), then add an alias

some queries will need a where clause

How many people have walked in the rain?

How far did a walker go if they completed all the coastal routes?

How long would it take to walk all the hill and mountain routes?

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