I have two tables:
TABLE1
id_attr
-------
1
2
3
TABLE2
id | id_attr | val
----------------------
10 | 1 | A
10 | 2 | B
As a result I want a table that show:
RESULT
id | id_attr | val
----------------------
10 | 1 | A
10 | 2 | B
10 | 3 | NULL
So I want the row with id=10 and id_attr=3 also when id_Attr=3 is missing in TABLE2 (and I know that because I have a NULL value (or something else) in the val column of RESULT.
NB: I could have others ids in table2. For example, after insert this row on table2: {11,1,A}, as RESULT I want:
id | id_attr | val
----------------------
10 | 1 | A
10 | 2 | B
10 | 3 | NULL
11 | 1 | A
11 | 2 | NULL
11 | 3 | NULL
So, for every id, I want always the match with all id_attr.
Your specific example only has one id, so you can use the following:
select t2.id, t2.id_attr, t2.val
from table2 t2
union all
select 10, t1.id_attr, NULL
from table1 t1
where not exists (select 1 from table2 t2 where t2.id_attr = t1.id_attr);
EDIT:
You can get all combinations of attributes and ids in the following way. Use a cross join to create all the rows you want and then a left join to bring in the data you want:
select i.id, t1.id_attr, t2.val
from (select distinct id from table2) i cross join
table1 t1 left join
table2 t2
on t2.id = i.id and t2.id_attr = t1.id_attr;
It sounds like you want to do just an outer join on id_attr instead of id.
select * from table2 t2
left outer join table1 t1 on t2.id_attr = t1.id_attr;
Related
I have two tables of data which I can join using a left join linked on the ID in both tables. Where the course and the person are the same, I need to populate the RegNumber as the same as the RegNumber which is already there for 1 row:
How it is currently: if I join table 1 and table 2 with a left join.
Table 1
ID | Course| Person
67705 | A | 1
68521 | A | 1
85742 | A | 1
89625 | A | 1
67857 | B | 2
86694 | B | 2
88075 | B | 2
88710 | C | 3
47924 | C | 3
66981 | C | 3
12311 | B | 1
12312 | B | 1
12313 | B | 1
Table 2
ID | RegNumber
67705 | N712316
NULL | NULL
NULL | NULL
NULL | NULL
67857 | N712338
NULL | NULL
NULL | NULL
NULL | NULL
47924 | M481035
NULL | NULL
12311 | N645525
NULL | NULL
NULL | NULL
I need table 2 to look like this:
ID | RegNumber
67705 | N712316
68521 | N712316
85742 | N712316
89625 | N712316
67857 | N712338
86694 | N712338
88075 | N712338
88710 | N712338
47924 | M481035
66981 | M481035
12311 | N645525
12312 | N645525
12313 | N645525
That is, I need to insert new rows into Table 2
Can anyone help me please? This is Totally beyond my capability!
insert into table2 (ID,RegNumber)
select t1.ID,reg.regNumber
from table1 t1
cross join (select top 1 regNumber from table2 r2 join table1 r1
on r1.Id = r2.Id
and r1.Course = t1.Course
and r1.Person = t1.person
order by id) reg
where not exists (select 1 from table2 t2 where t1.ID = t2.ID)
you can improve performance a little bit by loading data into temp table first :
select t1.ID , Course,Person,regNumber
into #LoadedData
from table1 t1
join table2 t2 on t1.Id = t2.ID
insert into table2 (ID,RegNumber)
select t1.ID,reg.regNumber
from table1 t1
cross join (select top 1 regNumber from #LoadedData l
where l.Course = t1.Course
and l.Person = t1.person
order by id) reg
where not exists (select 1 from #LoadedData l where t1.ID = l.ID)
in either case having an index on (ID, Course, Person) will help with performance
Assuming:
You are missing items in table 2 that inherit data from other records in table 1.
What makes two different IDs share the same Regnumber is to have BOTH course and person number in common.
You really need to join table 1 to itself to create the mapping that associates ID 67705 with ID 68521, then you can join in table 2 to pick up the Regnumber.
Try this:
Insert into table2 (ID,RegNumber)
Select right1.ID, left2.RegNumber
From (
(table2 left2 INNER JOIN
table1 left1 On (left1.ID=left2.ID)
INNER JOIN table1 right1 On (left1.Course=right1.Course AND left1.Person=right1.Person)
) LEFT OUTER JOIN table2 right2 On (right1.ID=right2.ID)
WHERE right2.ID Is Null
The 4th table join (alias right2) is purely defensive, to handle two records in table2 having identical Person & Course in table1.
I have solved this myself.
I concatenated the person and course columns and then joined them using that new concatenated field
insert into table 2 (ID,RegNumber)
select X1.ID,X2.Regnumber
from (select concat(course,person) as X,ID from table1) X1
join (select concat(t1.course,t1.person) as X, t2.RegNumber
from table1 t1
join table2 t2 on t1.ID = t2.ID) X2
on X1.X = X2.X
where X1.ID not in (select ID from table2)
I have two tables with shared key and I'm trying to join them to filter data based on few conditions
tbl1
id | OutPutValue |
1 | 2019 |
2 | 2018 |
tbl2
object_id | status | type |
1 | 22 | a |
1 | 22 | c |
1 | 33 | b |
2 | 33 | c |
2 | 33 | c |
2 | 33 | c |
What I'm trying to get is : it must select all 'OutPutValue' from tbl1 where, in tbl2 column 'type' should be c, and column 'status' must have same value for all rows i.e. 33. Note that Primary key (id) of tbl1 is foreign key (object_id) in tbl2.
Select column from tbl1 if, All rows in tbl2 (id of tbl1 have multiple rows (based on object_id) in tbl2) have same status value i.e. 33 and Type should be 'c'.
OutPutValue | Type | status |
2018 | c | 33 |
I have tried with following solution, but it's not returning desired output :
SELECT a.OutPutValue FROM tbl1 a JOIN tbl2 b ON a.id = b.object_id WHERE b.Type =c
GROUP BY a.OutPutValue, b.status HAVING b.STATUS IN(33)
You can try using correlated subquery
DEMO
select distinct OutPutValue,type, status
from t2 a inner join t1 b on a.object_id=b.id
where type='c' and not exists
(select 1 from t2 a1 where a.object_id=a1.object_id and status<>33 and type='c')
OUTPUT:
OutPutValue type status
2018 c 33
Another solution could be the following :
SELECT T1.id, T1.outputvalue FROM tbl1 T1
JOIN (
SELECT tbl2.*, MAX(type), MAX(status)
FROM tbl2
GROUP BY object_id
HAVING
MIN(status) = MAX(status) AND
MIN(type) = MAX(type)
) T2 ON T1.id = T2.object_id
WHERE T2.type = 'c'
EDIT: I have updated my query to match a particular case which make it quite similar to another answer.
FIND A DEMO HERE
Try a join combined with an aggregation:
SELECT
t1.OutPutValue,
MAX(t2.type) AS type,
MAX(t2.status) AS status
FROM tbl1 t1
INNER JOIN tbl2 t2
ON t1.id = t2.object_id
GROUP BY
t1.id,
t1.OutPutValue
HAVING
MIN(t2.status) = MAX(t2.status) AND
MAX(t2.status) = 33 AND
MIN(t2.type) = MAX(t2.type) AND
MAX(t2.type) = 'c';
I have a following table called Test:
Id | SomeId | Value
-----------------------------------------------------
019D9E52-41D1-45DF-81B6-C7CC484115A7 | 1 | 1
262640CA-65C2-4E30-8654-E187ACA1EEF4 | 1 | 1
53710AFC-4E19-4B1C-B68B-CDB713EC3D62 | 1 | 2
8FF7E77C-D04C-4961-82D9-87C2E5A1A096 | 1 | 2
-----------------------------------------------------
119D9E52-41D1-45DF-81B6-C7CC484115A7 | 2 | 1
762640CA-65C2-4E30-8654-E187ACA1EEF4 | 2 | 1
93710AFC-4E19-4B1C-B68B-CDB713EC3D62 | 2 | 2
4FF7E77C-D04C-4961-82D9-87C2E5A1A096 | 2 | 2
And there is a view called TestView:
SomeId | Value | Description
----------------------------
1 | 1 | 'One'
1 | 2 | 'Two'
1 | 3 | 'Three'
----------------------------
2 | 1 | 'One'
2 | 2 | 'Two'
These are just pseudo code examples.
I want to count all the values from the Test table (for a specific [SomeId]), and if value from the TestView (with a specific [SomeId]) is not in the Test table I just want to display 0 as count.
If I wanted to count values WHERE [Test].[SomeId] = 1, here's the expected result:
Value | Count
-----------------
One | 2
Two | 2
Three | 0
This is my query so far:
SELECT
tv.[Description] AS [Value],
COUNT(t.[Id]) - COUNT(tv.[Value]) AS [Count]
FROM [TestView] AS tv
LEFT JOIN [Test] AS t ON
t.[SomeId] = tv.[SomeId]
AND t.[Value] = tv.[Value]
WHERE
t.[SomeId] = 1
GROUP BY
tv.[Description]
But this gives me bad result... Anyways, here's the SQL Fiddle
EDIT:
This is just an addition to a Test table. What is Test table has one more foreign key Id, let's call it OtherId. Now when I use the query from the answer I won't get the result I wanted. Here's the modified query:
SELECT
t1.Description AS Value,
COUNT(t2.Value) AS Count
FROM TestView t1
LEFT JOIN test t2
ON t1.Value = t2.Value AND t1.SomeId = t2.SomeId
WHERE t1.SomeId = 1
AND t2.[OtherId] = *something* -- this is the addition
GROUP BY t1.Value, t1.Description
ORDER BY t1.Value;
Try this:
SELECT
t1.Description AS Value,
COUNT(t2.Value) AS Count
FROM TestView t1
LEFT JOIN test t2
ON t1.Value = t2.Value AND t1.SomeId = t2.SomeId
WHERE t1.SomeId = 1
GROUP BY t1.Value, t1.Description
ORDER BY t1.Value;
Demo
Below is your Solution
SELECT
tv.[Description] AS [Value],
COUNT(t.[Id]) AS [Count]
FROM [TestView] AS tv
LEFT OUTER JOIN [Test] AS t ON tv.SomeId = t.SomeId
AND t.Value = tv.value
AND t.[SomeId] = 1
GROUP BY
tv.[Description]
If I have tables like this:
t1:
id | name
----+------
1 | a
2 | b
3 | c
4 | d
t2:
id | value
----+-------
10 | xxx
20 | yyy
30 | zzz
t_join:
t1_id | t2_id
-------+-------
1 | 10
2 | 20
3 | 30
A SELECT query for t1.id=1 looks like:
SELECT t1.id, t1.name, t2.value FROM t1, t2,t_join WHERE t1.id=t_join.t1_id AND t2.id=t_join.t2_id AND t1.id=1;
And of course returns:
id | name | value
----+------+-------
1 | a | xxx
If I do the same thing with id=4, I get nothing.
SELECT t1.id, t1.name, t2.value FROM t1, t2,t_join WHERE t1.id=t_join.t1_id AND t2.id=t_join.t2_id AND t1.id=4;
id | name | value
----+------+-------
(0 rows)
And, if I do the same thing with a nonsense id=1234132, I also get nothing.
SELECT t1.id, t1.name, t2.value FROM t1, t2,t_join WHERE t1.id=t_join.t1_id AND t2.id=t_join.t2_id AND t1.id=1234132;
id | name | value
----+------+-------
(0 rows)
Is there a way I can differentiate between having an empty result (id=4) vs something that's null (id=1234132)? I guess I want verification that the id I'm checking exists without a separate query. Is this possible?
How about a left join:
SELECT t1.id, t1.name, t2.value
FROM t1 LEFT JOIN
t_join
ON t1.id = t_join.t1_id LEFT JOIN
t2
ON t2.id = t_join.t2_id
WHERE t1.id = 1;
If t.id is not found, you'll get no rows. If there are no matches in t2, then you'll get a NULL value.
Also, a simple rule: Never use commas in the FROM clause. Always, always use proper, explicit JOIN syntax.
Let us suppose the following table (e.g. a result of several inner join statements):
id | column_1 | column_2
------------------------
1 | 1 |
2 | 2 | 2
3 | | 3
Which you could for example get from the following statement:
select a.id, t1.column_1, t2.column_2
from a
left join t1 on a.id = t1.id
left join t2 on a.id = t2.id
Now, if i'd like to sum up t1.column_1 and t2.column_2 as follows
select
a.id,
t1.column_1,
t2.column_2,
(t1.column_1 + t2.column_2) as cumulated
from a
left join t1 on a.id = t1.id
left join t2 on a.id = t2.id
The result will look as follows:
id | column_1 | column_2 | cumulated
------------------------------------
1 | 1 | NULL | NULL
2 | 2 | 2 | 4
3 | NULL | 3 | NULL
My question basically is: is there a way to typecast NULL into 0 in order to do some math?
I have tried CONVERT(t1.column_1, SIGNED) and CAST(t1.column_1 as SIGNED), but a NULL stays a NULL.
Use IFNULL(column, 0) to convert the column value to zero.
Alternatively, the COALESCE function will do the same thing: COALESCE(column, 0), except
COALESCE is ANSI-compliant, IFNULL is not
COALESCE takes an arbitrary number of columns/values and will return the first non-null value passed to it.