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Return with false, if there are no results #4

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Return with false, if there are no results #4

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Return status and return with false, if there are no results
antti-begin May 10, 2016
9f1f1db
When column value is null, it cannot be joined with equality
antti-begin May 11, 2016
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16 changes: 12 additions & 4 deletions colpivot.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ create or replace function colpivot(
out_table varchar, in_query varchar,
key_cols varchar[], class_cols varchar[],
value_e varchar, col_order varchar
) returns void as $$
) returns boolean as $$
declare
in_table varchar;
col varchar;
Expand Down Expand Up @@ -74,6 +74,11 @@ create or replace function colpivot(
query := query || '_key.' || quote_ident(col) || ' ';
i := i + 1;
end loop;
-- empty resultset, bail out
if n_clsc_cols is null then
execute ('drop table ' || in_table);
return false;
end if;
for j in 1..n_clsc_cols loop
query := query || ', ';
col := '';
Expand All @@ -86,6 +91,7 @@ create or replace function colpivot(
ali := '_clsc_' || j::text;
query := query || '(' || replace(value_e, '#', ali) || ')' || ' as ' || quote_ident(col) || ' ';
end loop;
-- from part
query := query || ' from (select distinct ';
i := 0;
foreach col in array key_cols loop
Expand All @@ -103,8 +109,10 @@ create or replace function colpivot(
foreach col in array key_cols loop
if i > 0 then
on_e := on_e || ' and ';
on_e := on_e || '(' || ali || '.' || quote_ident(col) || ' = _key.' || quote_ident(col) || ' OR (' || ali || '.' || quote_ident(col) || ' IS NULL AND _key.' || quote_ident(col) || ' IS NULL)) ';
else
on_e := on_e || ali || '.' || quote_ident(col) || ' = _key.' || quote_ident(col) || ' ';
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Why does the first column not get the null comparison check? It's probably obvious but it was so long that I wrote this code.

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Beats me. I would have to test the function with and without checking for null. I'm also in the "fire and forget" mode 😆 But as I use it in the production, I guess it works regardless of maybe useless bloat.
I will check it out, if I have time for it.

end if;
on_e := on_e || ali || '.' || quote_ident(col) || ' = _key.' || quote_ident(col) || ' ';
i := i + 1;
end loop;
for k in 1..n_class_cols loop
Expand All @@ -116,7 +124,7 @@ create or replace function colpivot(
-- raise notice '%', query;
execute ('create temp table ' || quote_ident(out_table) || ' on commit drop as ' || query);
-- cleanup temporary in_table before we return
execute ('drop table ' || in_table)
return;
execute ('drop table ' || in_table);
return true;
end;
$$ language plpgsql volatile;