regularexpression for this text sql statement or a program? - sql

Question

Heres specifically the sql text in a file.
select substr(to_char(ctl.tody_run_dt,'YYYYMMDD'),1,8) tody_yyyymmdd,
substr(to_char(cdr.nxt_proc_dt,'YYYYMMDD'),1,8) nxt_proc_yyyymmdd,
add_months(ctl.tody_run_dt - cdr.past_accru_dys,
- ct.nbr_cycl_for_adj) beg_proc_dt,
from tbl_crd )
and prv.calendar_run_dt =
( select max(calendar_run_dt)
from run_tbl1 prv2
From this i wish to extract all the tables,
This seems pretty complicated to be done through a regexp? Is there a way? Or should i write a program? I just cant come up with an algorithm.

Answer 1

You might be able to do something like a linear search like this. It relaxed for your example
and just targets the from keyword, excludes other keywords.
The table data is captured in group 1. It has to be split appart upon each
match through the find loop.
# from\s+((?!(?:select|from|where|and)\b)\w+(?:[,\s]+(?!(?:select|from|where|and)\b)\w+)*)
from
\s+
( # (1 start), Contains all the table info
(?! # exclude keywords
(?:
select
| from
| where
| and
)
\b
)
\w+
(?:
[,\s]+
(?! # exclude keywords
(?:
select
| from
| where
| and
)
\b
)
\w+
)*
) # (1 end)
Perl test case
$/ = undef;
$str = <DATA>;
while ( $str =~ /from\s+((?!(?:select|from|where|and)\b)\w+(?:[,\s]+(?!(?:select|from|where|and)\b)\w+)*)/g )
{
print "\n'$1'";
}
__DATA__
select substr(to_char(ctl.tody_run_dt,'YYYYMMDD'),1,8) tody_yyyymmdd,
substr(to_char(cdr.nxt_proc_dt,'YYYYMMDD'),1,8) nxt_proc_yyyymmdd,
add_months(ctl.tody_run_dt - cdr.past_accru_dys,
- ct.nbr_cycl_for_adj) beg_proc_dt,
(ctl.tody_run_dt + cdr.futr_accru_dys) end_proc_dt,
ctl.tody_end_proc_dt,
ctl.prv_end_proc_dt,
cdr.fst_proc_dy,
cdr.lst_proc_dy,
cdr.accru_nbr_of_dys,
cdr.dy_of_wk,
from run_tbl1 cdr, runtbl
run_tbl1 prv,
run_tbl_cntl ctl,
tbl_crd ct
where cdr.calendar_run_dt = ctl.tody_run_dt
and ct.nbr_cycl_for_adj =
( select max(nbr_cycl_for_adj)
from tbl_crd )
and prv.calendar_run_dt =
( select max(calendar_run_dt)
from run_tbl1 prv2
where prv2.calendar_run_dt < ctl.tody_run_dt
and prv2.accru_nbr_of_dys = 1 )
and rownum = 1
Output >>
'run_tbl1 cdr, runtbl
run_tbl1 prv,
run_tbl_cntl ctl,
tbl_crd ct'
'tbl_crd'
'run_tbl1 prv2'

Answer 2

First I had to correct some syntax errors within your SQL.
... cdr.dy_of_wk, <<<< the comma is wrong
from run_tbl1 cdr ...
Here the proove of concept using JSQLParser V0.8.9 (https://github.com/JSQLParser/JSqlParser) to extract tablenames.
public static void main(String[] args) throws JSQLParserException {
TablesNamesFinder tfinder = new TablesNamesFinder();
String sql = "select substr(to_char(ctl.tody_run_dt,'YYYYMMDD'),1,8) tody_yyyymmdd, "
+ " substr(to_char(cdr.nxt_proc_dt,'YYYYMMDD'),1,8) nxt_proc_yyyymmdd, "
+ " add_months(ctl.tody_run_dt - cdr.past_accru_dys, "
+ " - ct.nbr_cycl_for_adj) beg_proc_dt, "
+ " (ctl.tody_run_dt + cdr.futr_accru_dys) end_proc_dt, "
+ " ctl.tody_end_proc_dt, "
+ " ctl.prv_end_proc_dt, "
+ " cdr.fst_proc_dy, "
+ " cdr.lst_proc_dy, "
+ " cdr.accru_nbr_of_dys, "
+ " cdr.dy_of_wk "
+ " from run_tbl1 cdr, runtbl, "
+ " run_tbl1 prv, "
+ " run_tbl_cntl ctl, "
+ " tbl_crd ct "
+ " where cdr.calendar_run_dt = ctl.tody_run_dt "
+ " and ct.nbr_cycl_for_adj = "
+ " ( select max(nbr_cycl_for_adj) "
+ " from tbl_crd ) "
+ " and prv.calendar_run_dt = "
+ " ( select max(calendar_run_dt) "
+ " from run_tbl1 prv2 "
+ " where prv2.calendar_run_dt < ctl.tody_run_dt "
+ " and prv2.accru_nbr_of_dys = 1 ) "
+ " and rownum = 1 ";
//parse SQL statement
Select select = (Select) CCJSqlParserUtil.parse(sql);
//extract table names
List<String> tableList = tfinder.getTableList(select);
System.out.println(tableList);
}
and it outputs
[run_tbl1, runtbl, run_tbl_cntl, tbl_crd]