Why I cannot call a function from within an SQL function?

Hi Ho!

The following query works well:

 select count (*)
 from item_audit
 where audit_ts >= '2008-05-30 00:00:00'
       and audit_ts <= '2008-10-30 00:00:00'
       and 'wst' != (select split_part(category, '-', 2)
                     from description
                     where split_part(category, '-', 1) = 'item'
                           and shorthand = status
                    )

But, when I transform it into the following SQL function, the function cannot be created barking:

 ERROR:  syntax error at or near "-"
 LINE 6:        and $1 != (select split_part(category, '-', 2)"

 create or replace function get_I(text, timestamp, timestamp) returns bigint as
'select count (*)
 from item_audit as ia
 where audit_ts >= $2
       and audit_ts <= $3
       and $1 != (select split_part(category, '-', 2)
                  from description
                  where split_part(category, '-', 1) = 'item'
                        and shorthand = ia.status
                 )
' language sql;

What's wrong?

Thank you.

Best regards,
Eus (FSF member #4445)

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