I have two tables which has relationships and I trying to update base table if there are no records in the child table.
Table1:
id value
1 abc
2 xyz
Table2:
id table1_id
1 1
2 1
So in this case I want to update table1 id 2 to pqr as it does not have associated rows in table2. For id 1 nothing happens.
I tried this way but this is completely wrong
update table1 set value = 'pqr'
from table1 t1 inner join table2 t2 on count(t2.table1_id) < 1
If you want to update the rows of table1 with ids that don't have a match in table2 in the column table1_id then you can do it with a LEFT JOIN and update the unmatched rows:
update t1
set t1.value = 'pqr'
from table1 t1 left join table2 t2
on t2.table1_id = t1.id
where t2.table1_id is null
See the demo.
Results:
> id | value
> -: | :----
> 1 | abc
> 2 | pqr
I believe you're looking for WHERE NOT EXISTS.
update table1
set value = 'pqr'
from table1 t1
WHERE
NOT EXISTS (SELECT 1 FROM table2 t2 WHERE t2.table1_id = t1.id);
Although this assumes you're asking the question in the title, not the one in the test of your question.
UPDATE table1
SET value = 'pqr'
WHERE id IN (SELECT t1.id FROM table1 t1 INNER JOIN table2 t2 ON t1.id = t2.table1_id)
Related
I have 3 tables with names and number of few of my friends.
Table 3 has correct data, table 2 has minute errors in data and table 1 has more than table 2.
if a user exists in table 2 and 3 then show table 3 details in output else table 2 details, if user is not even there in table 2 then show user data from table1.
more like a preference order.
DUMMY DATA:
table 1 :
name phone
abc 2343
bcd 3434
ccd 3455
ffc 4545
table 2 :
name phone
abc 2313
bcd 3414
ccd 3415
table 3 :
name phone
abc 2344
bcd 3431
expected output :
name phone
abc 2344
bcd 3431
ccd 3415
ffc 4545
I tried this query but unable to find correct output.
select phone,
coalesce(table1.name, TABLE2.name,TABLE3.name) as namee
FROM TABLE1
left JOIN TABLE2
ON table1.name = table2.name
INNER JOIN table3
ON table3.name = table2.name
Would be a huge, huge heeelppppp.
Gordon was close; he had the preference backwards. Please make sure you understand why the script works.
-- grab all our preferred data first
select t3.*
from table3 t3
union all
-- grab anything that doesn't exist in our preferred table
select t2.*
from table2 t2
where not exists (select 1 from table3 t3 where t3.name = t2.name)
union all
-- grab anything that doesn't exist in our preferred tables
select t1.*
from table1 t1
where not exists (select 1 from table2 t2 where t2.name = t1.name) and
not exists (select 1 from table3 t3 where t3.name = t1.name);
Use union all:
select t1.*
from table1 t1
union all
select t2.*
from table2 t2
where not exists (select 1 from table1 t1 where t1.name = t2.name)
union all
select t3.*
from table3 t3
where not exists (select 1 from table1 t1 where t1.name = t3.name) and
not exists (select 1 from table2 t2 where t2.name = t3.name);
Say I have two tables. E.g,
Table 1:
Store Product
1 2
1 1
2 3
2 4
And Table 2
Store Product
1 2
2 3
How do I delete all the rows in Table 1 that are also in Table 2?
So, new Table 1 would be:
Store Product
1 1
2 4
You seem want :
select t1.*
from table1 t1
where not exists (select 1
from table2 t2
where t2.store = t.store and
t2.product = t1.product
);
Similarly delete version would be :
delete
from table1 t1
where exists (select 1
from table2 t2
where t2.store = t.store and
t2.product = t1.product
);
You can use something like this:
DELETE
t1
FROM
table1 t1
WHERE
(t1.store, t1.product) IN ( SELECT
t2.store,
t2.product
from
table2 t2);
I have the following table structures:
Table1
--------------
Table1Id
Field1
Field2
Table2
------------
Table2Id
Table1Id
Field1
Field2
Table3
-----------
Table3Id
Table1Id
Field1
Field2
I need to be able to select all fields in Table1, count of records in Table2, and count of records in Table3 Where count of records in Table2 > count of records in Table3
Here is an example of expected output with the given data:
Table1 Data
-------------
1 Record1Field1 Record1Feild2
2 Record2Field1 Record2Feild2
3 Record3Field1 Record3Feild2
4 Record4Field1 Record4Feild2
Table2 Data
------------
1 1 Record1Field1 Record1Feild2
2 1 Record2Field1 Record2Feild2
3 2 Record3Field1 Record3Feild2
4 2 Record4Field1 Record4Feild2
5 2 Record5Field1 Record5Feild2
6 4 Record6Field1 Record6Feild2
7 4 Record6Field1 Record6Feild2
8 4 Record6Field1 Record6Feild2
Table3 Data
------------
1 2 Record1Field1 Record1Feild2
2 2 Record2Field1 Record2Feild2
3 3 Record3Field1 Record3Feild2
4 3 Record4Field1 Record4Feild2
5 3 Record5Field1 Record5Feild2
6 4 Record6Field1 Record6Feild2
Desired Results
Table1Id Field1 Field2 Table2Count Table3Count
1 Record1Field1 Record1Field2 2 0
2 Record2Field1 Recird2Field2 3 2
4 Record4Field1 Recird4Field2 3 1
Notice record 3 in Table 1 is not shown because the record count in Table2 is less than the record count in Table3. I was able to make this work using a very ugly query similar to the one below but feel there is a much better way to do this using joins.
SELECT
t1.Table1Id,
t1.Field1,
t1.Field2
(Select Count(Table2Id) From Table2 t2 Where t2.Table1Id = t1.Table1Id) as Table2Count,
(Select Count(Table3Id) From Table3 t3 Where t3.Table1Id = t1.Table1Id) as Table3Count,
From
Table1 t1
Where
(Select Count(Table2Id) From Table2 t2 Where t2.Table1Id = t1.Table1Id) > (Select Count(Table3Id) From Table3 t3 Where t3.Table1Id = t1.Table1Id)
Hard to test it without working examples but something along these lines should be a good starting point.
SELECT
t1.Table1Id,
t1.Field1,
t1.Field2,
COUNT(DISTINCT t2.Table2Id),
COUNT(DISTINCT t3.Table3Id)
From Table1 t1
LEFT OUTER JOIN Table2 t2 ON t1.Table1Id = t2.Table1Id
LEFT OUTER JOIN Table3 t3 ON t1.Table1Id = t3.Table1Id
GROUP BY t1.Table1Id
HAVING COUNT(DISTINCT t2.Table2Id) > COUNT(DISTINCT t3.Table3Id)
You could get all the value in t1 and the data form t2 e t3 for your comparision using a couple of join on grouped values
SELECT
t1.Table1Id
,t1.Field1
,t1.Field2
, tt2.count_t2
, tt3.count_t3
from table1 t1
join (
select Table1Id, count(*) count_t2
From Table2
group by Table1Id
) tt2 on tt2.Table1Id = t1.Table1Id
join (
select Table1Id, count(*) count_t3
From Table3
group by Table1Id
) tt3 on tt3.Table1Id = t1.Table1Id
where tt2.count_t2 < tt3.count_t3 <
I have the following tables where a few of the columns are included here:
Table 1:
Id RefId PhoneNumber
1 11 919191
2 11 888888
3 11 919191
Table 2:
Id RefId City UniqueId
1 11 Mumbai 111
2 11 Pune 222
3 11 Nashik 333
I want a few columns from Table1 and Table2. Common in both table is RefId. Table2 has UniqueId which is primary key of Table2. If I do an inner join based on RefId I will get 9 records, but I want 3. How do I get that?
Here is my query:
SELECT T1.PhoneNumber,T2.City,T2.UniqueId,T2.RefId
FROM Table1 T1
INNER JOIN Table2 T2
ON T1.RefId = T2.RefId
If the ID is used to join as well then
SELECT t1.Id, t1.RefId, t1.PhoneNumber, t2.City, t2.UniqueId
FROM Table1 t1
INNER JOIN Table2 t2
ON t1.Id = t2.Id
AND t1.RefId = t2.RefId
If the Ids are randomly generated them you probably shouldn't join on them.
If the Ids were random but all of the PhoneNumbers were for the same place then you could just pick the Minimum value PhoneNumber (or Max)
SELECT t2.RefId, t1.PhoneNumber, t2.City, t2.UniqueId
FROM Table2 t2
INNER JOIN (
SELECT RefId, MIN(PhoneNumber) AS PhoneNumber
FROM Table1
GROUP BY RefId
) t1 ON t1.RefId = t2.RefId
I have two tables:
id
1
2
3
4
t1 AND t2
id | related_id
1 | 2
1 | 3
Where t2 is relationship table between t1 records. What is the best way to get desired output?
t1.id | t1_copy.id
1 | NULL -- want to get this NULL row
1 | 2
1 | 3
Simple JOIN would almost work, however it doesn't give me the first NULL row.
SELECT t1.id, t1_copy.id FROM t1
LEFT JOIN t2 ON t1.id = t2.id
LEFT JOIN t1 t1_copy ON t1_copy.id = t2.related_id
WHERE t1.id = 1
P.S: Yes, I do realize that desired output is wacky.
Seems like a simple UNION should do the trick
SELECT
id,
null as copy_id
FROM
t1
WHERE
exists (select * from t2 where t1.id = t2.id)
UNION ALL
SELECT
t1.id,
t2.related_id
FROM
t1
INNER JOIN t2
ON t1.id = t2.id
SQL Fiddle
SELECT DISTINCT t1.id, t1_copy.id FROM t1
LEFT OUTER JOIN t2 ON t1.id = t2.id
WHERE t1.id = 1