Iterating over integer[] in PL/pgSQL

问题:

I am trying to loop through an integer array (integer[]) in a plpgsql function. Something like this:

declare     a integer[] = array[1,2,3];     i bigint; begin     for i in a loop      raise notice "% ",i; end loop; return true; end

In my actual use case the integer array a is passed as parameter to the function. I get this error:

ERROR:  syntax error at or near "$1" LINE 1:   $1

How to loop through the array properly?

回答1:

DECLARE    a integer[] := array[1,2,3];    i integer;                   -- int, not bigint! BEGIN FOR i IN 1 .. array_upper(a, 1) LOOP    RAISE NOTICE '%', a[i];      -- single quotes! END LOOP; RETURN TRUE; END

Or try the new FOREACH in PostgreSQL 9.1:

FOREACH i IN ARRAY a LOOP     RAISE NOTICE '%', i; END LOOP;

However, set-based solutions with generate_series() or unnest() are often faster than looping for big sets.

Basic examples:

• PostgreSQL: Frequency Table Expansion
• Select each month between a start and end date

Search the tags generate-series or unnest for more.

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