I believe precondition and postcondition details are stored in the JPOV table, but each rule is split into multiple parts that are stored in multiple rows of this table.
This query doesn't solve your issue, but should point you in the right direction of understanding how this data is stored;
select
CASE CONVERT(VARCHAR,JPOV_Location)
WHEN 1 THEN 'PreCondition'
WHEN 2 THEN 'PostCondition'
END "Source",
a.OH_Name, oh_client,
'task#' + convert(varchar,b.jpov_jpp_lnr) + ' line#' + convert(varchar,b.jpov_jppo_lnr) "Line_Number",
b.jpov_value "Script_Content"
from OH a
inner join JPOV b on a.OH_IDNR=b.JPOV_OH_IDNR
where a.OH_DELETEFLAG=0 and oh_client = &$client#
and a.OH_REFIDNR=0
and b.jpov_oh_idnr = 1197020 -- ID of desired workflow
and b.jpov_jpp_lnr = 3 -- ID of desired task