Python3 FOR loop does not loop over all parameters list used to pass in postgressql parameters

Question

I have a meteorological data set.

1. Query: First query returns me a list a all ids and idmms for active automatic measuring stations

sql_boberamp = """select a.id, a.idmm
                  from id_obs a, idmm b 
                  where a.tip=4 and 
                      a.datum_konca='10000-1-1' 
                      and b.idmm=a.idmm and a.id in 
                      (select c.id 
                       from parametri c 
                       where c.id_parametra>3005 and 
                           c.datum_konca='10000-1-1') order by 
                           a.idmm"""
cur1.execute(sql_boberamp)
boberamp_lst = cur1.fetchall()

Columns id and idmm can be turned into dictionary

2. Query: I pass in 3 parameters. Query counts for one amp how many times each observed parameter was measured for specific day.

ids = 2210
idmms = 11
params = idmms, idmms, idmms, ids
testtable_sql = []
sql_stevec = """select a.id_parametra,
                    case when  a.id_parametra in 
                        (3005,3010,3011,3040,3045,3046,3047, 3391) 
                        then (select count(*) from amp_o b where 
                        b.datum='2018-04-16' and b.par=a.id_parametra                             
                        and b.tip=4 and b.idmm=%s)
                    when a.id_parametra in (3120, 3121, 3124, 3420) 
                        then (select count(*) from amp_p_10min b where 
                        b.datum='2018-04-16' and b.par=a.id_parametra 
                        and b.tip=4  and b.idmm=%s)
                    when a.id_parametra in (3180, 3181, 3188, 3189) 
                        then (select count(*) from amp_v b where 
                        b.datum='2018-04-16' and b.par=a.id_parametra 
                        and b.tip=4  and b.idmm=%s)
                end as stevec
                from parametri a
                where a.id=%s and datum_konca='10000-1-1' and 
                        a.id_parametra>3000
                order by a.id_parametra"""

cur.execute(sql_stevec,params)
testlist2_sql = cur.fetchall()
testtable_sql.append(testlist2_sql)

My goal is to get query 3 running.

3 Query: This FOR loop should run query 2 (query counts for one amp how many times each measured parameter was measured for specific day) for all my working amps.

ids = [2210, 2662,872]
idmms = [11,1948, 907]
testtable_for_sql = []

for row in ids:
    ids_row = ids[0]
        for row in idmms:
            idmms_row = idmms[0]

            params = idmms_row, idmms_row, idmms_row, ids_row
            print(params)
            cur.execute(sql_stevec,params)
            testlist_for_sql = cur.fetchall()
            testtable_for_sql.append(testlist_for_sql)
            print('----    inside FOR loop ----',testtable_for_sql)
print('---- outside FOr loop ----',testtable_for_sql)

This is my result:

(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
(11, 11, 11, 2210)
('----    inside FOR loop ----', [])
('---- outside FOr loop ----', [])

I don't understand, why it doesn't go through all three rows that are in my data for ids and idmms. I just can' crack this FOR loop in python script. Thank you very much for your help.

I have corrected this. I added counter i = 0 outside for loop and corrected ids [0] into ids[i] and i +=1 inside for loop. — vvidmar
– vvidmar, Commented Apr 25, 2018 at 11:31

Jacobr365 · Accepted Answer · 2018-04-24 16:19:45Z

1

I think this is what you are looking for. You were using idmms[0] and ids[0] so you were only ever using the first item in each list and ignoring the iteration essentially.

ids = [2210, 2662,872]
idmms = [11,1948, 907]
testtable_for_sql = []

for ids_row in ids:
    for idmms_row in idmms:
        params = idmms_row, idmms_row, idmms_row, ids_row
        print(params)
        cur.execute(sql_stevec,params)
        testlist_for_sql = cur.fetchall()
        testtable_for_sql.append(testlist_for_sql)
        print('----    inside FOR loop ----',testtable_for_sql)
print('---- outside FOr loop ----',testtable_for_sql)

answered Apr 24, 2018 at 16:19

Jacobr365

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1 Comment

vvidmar Over a year ago

It worked perfectly. Now I see that I need some more corrections to my code, because ids and idmms are 'couple' together and I get 4 result lists instead of 2 that I need.

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