Aside from your database structure being problematic, what are you
trying to accomplish?
In other words, what do you want to replace the nulls with and in what
circumstance?
I imagine your table looks like this
ID,country,1950,1951,1952,1953,....
1 usa 50 null 70 10
2 canada 10 45 null 4
Please mention what you would like to do with this?
Stefan Schwarzer wrote:
On Thu, Sep 07, 2006 at 07:45:19AM +0200, Stefan Schwarzer wrote:
Hi there,
is there a simple way to replace NULL values in multiple columns
within the SQL statement? I changed the underlaying country template
of your database; so now there are a couple of NULL values when I
join the stats-table with the country table. Unfortunately, my
queries have always multiple (year) columns, so I can't do a kind of
manual replace.
I found that the COALESCE command does something like this, but I
couldn't figure out how this works.
Yes, COALESCE replaces NULLs, however your examples have neither NULLs
nor use COALESCE, so I don't understand what your question is.
Please repost with an actual example of your problem.
As I said, I couldn't figure out how COALESCE would work on multiple
columns (without naming them explicitly).
So, say I have a table with columns for each year between 1970 and 2005.
For specific countries the values might be NULL, depending if the
statistical table has been updated recently (then they will have a
value), or not (then they will be NULL). A sample query would thus be
something like:
SELECT * FROM pop_density
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
