I have 2 tables
Table 1
ID Status
1 D
2 F
3 D
Table 2
SID ID Approve
1 1 N
2 1 Y
3 1 Y
4 2 Y
5 3 Y
Result:- Should be
Table 1 (ID, Status)
3, D
2,F
Should not display 1 (As one of child rows have N in the Approve Column)
I need a query to joins 2 tables on ID and finds records that don not have N in their Approve column. Does anyone have any clue how to implement this?
I tried
SELECT * FROM Table1 AS t1
INNER JOIN Table2 AS t2
ON t2.id = t1.id
WHERE t2.Approve != 'N'
Doesn’t work
SELECT *
FROM Table1 t1
WHERE NOT EXISTS(SELECT * FROM Table2 t2 WHERE t2.ID = t1.ID AND t2.Approve = 'N')
More efficient and possibly easier to read is the following:
SELECT * FROM Table1 AS t1
LEFT JOIN Table2 AS t2
ON t2.id = t1.id
group by t1.id HAVING sum(t2.approve='Y') = count(t1.id)
Please Try
SELECT distinct t1.*
FROM Table1 AS t1
INNER JOIN Table2 AS tyes
ON tyes.id = t1.id
AND tyes.approve ='Y'
LEFT OUTER JOIN Table2 as tno
ON tno.id = t1.id
AND tno.approve ='N'
where tno.sid is null
It will select any line which is explicitely approved and never disapproved
Select * from table1 where id not in (select id from table2 where approve = 'N')
ID 1 is still returned since there is also a record in table 2 where approve = 'Y' for ID 1.
If you want to exclude any ID where approve is 'N' for any SID then you'll have to work with subqueries; roughly:
SELECT t1.ID,T1.Status FROM Table1 AS t1 INNER JOIN Table2 AS t2 ON t2.id = t1.id
where t1.id NOT IN (select id from Table2 where approve = 'N' and id = t1.id)
regards,
Stijn
Related
I have a 3 tables, one with these two columns
table1:
id, name
0 foo
1 etc
2 example
table2:
id table1_id
0 1
1 0
2 2
table3:
id table2_id
0 1
1 0
2 0
Which query can I find all 'name's from table1 where ALL ids in table2 have a count of atleast n in table3? i.e if n was 1 it should return foo and etc
EDIT:
Explained poorly, I'm trying to get the name of every record in table1 where ALL corresponding records in table2 (i.e records where the column table1_ID is equal to each id within table1. In my example tables, each ID has one) have a count in table3 of atleast n.
If n was 1, as the table2_id 0 appears twice in records 1 and 2, its 'parent' would be returned. It corresponds to the table 1 record 1, so the name of the record with table1 id: 1 should be returned, which is etc. Example also as it has a count of 1 in the bottom column, however foo does not appear so it shouldnt.
Expected result:
name
foo
etc
You can do this using a subquery in the where clause:
select t1.*
from table1 t1
where (select count(t3.id)
from table2 t2 left join
table3 t3
on t3.table2_id = t2.id
where t2.table1_id = t1.id
group by t2.id
order by count(*) asc -- to get the minimum
limit 1
) >= ? -- value you care about
I suspect that this might have the best performance with appropriate indexes: table2(table1_id, id) and table3(table2_id).
If I have understood the question - if a check on table3.table2_id is greater than 0, the answer would be 'etc' ?
Code below
select t1.name
from
(
select 0 as id, 1 as table2_id
union select 1, 0
union select 2 , 0
) t3
inner join
(
select 0 as id , 1 as table_id
union select 1, 0
union select 2, 2
) t2 on t2.table_id = t3.table2_id
inner join
(
select 0 as id, 'foo' as name
union select 1 , 'etc'
union select 2 , 'example'
) t1 on t1.id = t2.table_id
where t3.table2_id > 0
select table1.name
FROM table1
INNER JOIN table2 ON table1.id=table2.table1_id
INNER JOIN table3 ON table2.id=table3.table2_id
GROUP BY table1.name
HAVING count(*) >= 1
replace the last 1 with whatever n you desire
Here's the sql fiddle if you want to play around with it: http://sqlfiddle.com/#!7/14217/4
Use an INNER join of table1 to table2 and then a LEFT join to table3 and count the corresponding ids of table3.
Then by a 2nd level of aggregation return only the rows of table1 where all the counters are at least 1:
SELECT id, name
FROM (
SELECT t1.id, t1.name, COUNT(t3.id) counter
FROM table1 t1
INNER JOIN table2 t2 ON t2.table1_id = t1.id
LEFT JOIN table3 t3 ON t3.table2_id = t2.id
GROUP BY t1.id, t1.name, t2.id
)
GROUP BY id, name
HAVING MIN(counter) >= 1 -- change to the number that you want
See the demo.
Results:
id
name
0
foo
1
etc
I have two tables that I want to join.
The case is in table 1 the default value is 1 then in table 2 the default value is 0
Table 1 Table 2
-------- ---------
1 0
1232342 1232342
1241232 1231231
I want to join table 1 and table 2 with condition that if table 2 is 0 then it will be replaced to 1.
SELECT T1.ID
FROM TABLE1 T1, TABLE2 T2
WHERE T1.ID = REPLACE(CASE WHEN T2 = 0 THEN 1 ELSE T2.ID END, 'X', 'E')
with this statement it does not return the other id's that are not 0 or 1
expected output
Table 1
--------
1
1232342
Use a join with a CASE. replace() is for string values:
select t1.*
from table1 t1
join table2 t2 on t1.id = case when t2.id = 0 then 1 else t2.id end;
use case when and sub-query
select t1.* from table1 t1 join
(
select case when t2.id=0 then 1 else t2.id end as id from table2 t2
) as t3 on t1.id=t3.id
Try using case when :
SELECT *
FROM TABLE1 T1 inner join TABLE2 T2
on T1.ID = (CASE WHEN T2.ID =0 THEN 1 ELSE T2.ID END)
Switch to modern, explicit JOIN syntax. Skip the case expression, simply use AND/OR instead:
SELECT T1.ID
FROM TABLE1 T1
JOIN TABLE2 T2
ON T1.ID = T2.ID OR (T1.ID = 1 and T2.ID = 0)
Or use INTERSECT:
SELECT ID FROM TABLE1
INTERSECT
SELECT case when ID = 0 then 1 else id end from TABLE2
Say we have two Users with ID = 1 and ID = 2
I know the ID of the current User and I need to execute different select statements depending on the ID.
if ID = 1
select a from table1
else if ID = 2
select b from table2
else
select c from table3
Is there a way to put this logic into single SQL query?
You can use union with appropriate where conditions.
select a from table1 where id = 1
union all
select b from table2 where id = 2
union all
select c from table3 where id not in (1,2)
or if the tables can be joined
select
case when t1.id = 1 then t1.a
when t2.id = 2 then t2.b
else t3.c end
from table1 t1
join table2 t2 on t1.id = t2.id
join table3 t3 on t1.id = t3.id
There are two table TABLE1 and TABLE2 in which there is a common field ID. I wanted to retrieve values from TABLE2 that doesnot match in TABLE1 based on ID value.
select * from TABLE2 where subject = 1 and ID NOT IN (select ID from TABLE1 where subject = 1)
Sample:
TABLE1 ID SUBJECT 1 1
TABLE2 ID SUBJECT 1 1 2 1
The expected result is 2 and it works fine.
But when TABLE1 is empty or the inner select ID from TABLE1 where subject = 1 returns empty, the whole select statement returns empty.
But the expected result is 1, 2
Is there any way to achieve this ?
Use a left join
select t2.*
from table2 t2
left outer join table1 t1 on t1.id = t2.id and t1.subject = 1
where t2.subject = 1
and t1.id is null
See a good explanation of joins
I think you can use not exists also for this work -
select * from TABLE2 where subject = 1 and NOT exists
(select 1 from TABLE1 where subject = 1 and table1.id = table2.id)
I have a problem joining two tables:
table1
id name
1 aaa
2 bbb
3 ccc
table2
id table1_id name
1 1 x1
2 1 x2
3 2 s1
table1 is the main table, table2 contains attributes.
I need to join and search both tables, but display distinct results from first table.
When using JOIN I get multiple results from table2.
The scenario is I need to search main table TABLE1 and ALL ATTRIBUTES in TABLE2 and return if found
select distinct(name) from table1 inner join table2 on table1.id = table2.table1_id where table2.name = x2;
Should do the trick.
If you need entries which exists in both tables:
SELECT * from Table1 t1
WHERE YourConditionsHere
AND EXISTS (SELECT 1 from Table2 t2
WHERE t1.Id = t2.Table1_id
AND YourConditionsHere)
if you need entries from Table1 for which does not exists enteries in Table2
SELECT * from Table1 t1
LEFT JOIN
(SELECT * from Table2
WHERE YourConditionsHere
) t2
ON (t1.Id = t2.Table1_id)
WHERE YourConditionsHereForTable1
another option
select * from table1 t1 where t1.id in (select table1_id from table2 t2 where t2.name = "x1");
it's probably best to check query plains (i.e. EXPLAIN) for all suggested queries and check the one that performs best for your exact scenario.