Using DB2 query, I need to fetch the address from Table A using multiple where condition and when the address is unknown in table A, I need to get the temporary address from Table B using multiple where condition from Both Table A and Table B.
The common field for both the table is Employee ID
Where condition should be,
A.Emp-dept = xxx
A.Emp-state = yyy
B.Emp-code = zzz
B.Emp-proj = AAA
I Tried the below query
SELECT A.EMP_ID
A.EMP_ADDR,
A.EMP_DEPT,
B.EMP_CODE,
B.EMP_TEMP_ADDR
FROM TAB A
LEFT OUTER JOIN TAB B
ON A.EMP_ID = B.EMP_ID
WHERE A.Emp_dept = xxx
A.Emp_state = yyy
B.Emp_code = zzz
B.Emp_proj = AAA
ORDER BY EMP_ID
But this query is not working, I am getting 0 rows as result
Expected Result
https://dbfiddle.uk/s7zr35wU
If there may or may not be a row in table B, then you need to put the filter in the ON clause instead of the WHERE. With it in the WHERE, you are basically treating table B as an INNER JOIN instead of a LEFT JOIN because it is joining the two tables together with the ON criteria, and then filtering it out with the WHERE criteria.
You need something like this:
SELECT A.EMP_ID
A.EMP_ADDR,
A.EMP_DEPT,
B.EMP_CODE,
B.EMP_TEMP_ADDR
FROM TAB A
LEFT OUTER JOIN TAB B
ON A.EMP_ID = B.EMP_ID
AND B.Emp_code = zzz
AND B.Emp_proj = AAA
WHERE A.Emp_dept = xxx
AND A.Emp_state = yyy
ORDER BY EMP_ID
This assumes that you are at least going to get a row from table A (with a NULL address or something). If that is not the case, you may need to use FULL OUTER JOIN instead of LEFT OUTER JOIN.
Related
In my query there is a value that will not match in the demand category table. Therefore, since one value does not match in the output of my query, other matching values do not appear.
I want to do;
How can I list other matching values even if there is an unmatched value in the query?
process Table
fk_unit_id fk_unit_position fk_demand_category
1 2 1
unit table
unit_id
1
unit_position table
unit_position
2
demand_category table
demand_category
1
Query:
SELECT unit_name,unit_position_name,demand_category_name From process
INNER JOIN unit ON process.fk_unit_id = unit_id and unit_id =1
INNER JOIN unit_position ON process.fk_unit_position_id = unit_position_id and unit_position_id = 2
INNER JOIN demand_category ON process.fk_demand_category_id = demand_category_id and demand_category_id =0 ;
Switch INNER JOIN on demand_category with LEFT JOIN
LEFT JOIN gets all records from the LEFT linked and the related record from the right table ,but if you have selected some columns from the RIGHT table, if there is no related records, these columns will contain NULL.
SELECT unit_name,unit_position_name,demand_category_name From process
INNER JOIN unit ON process.fk_unit_id = unit_id and unit_id =1
INNER JOIN unit_position ON process.fk_unit_position_id = unit_position_id and unit_position_id = 2
LEFT JOIN demand_category ON process.fk_demand_category_id = demand_category_id and demand_category_id =0 ;
You can use outer join to have the columns that don't match, just the corresponding values in other table will be padded with null. Other way is to use IN operator, but slower query performance.
I have two tables A and B.
Both the tables have same number of columns.
Table A always contains all ids of Table B.
Need to fetch row from Table B first if it does not exist then have
to fetch from Table A.
I was trying to dynamically do this
select
CASE
WHEN b.id is null THEN
a.*
ELSE
b.*
END
from A a
left join B b on b.id = a.id
I think this syntax is not correct.
Can some one suggest how to proceed.
It looks like you want to select all columns from table A except when a matching ID exists in table B. In that case you want to select all columns from table B.
That can be done with this query as long as the number and types of columns in both tables are compatible:
select * from a where not exists (select 1 from b where b.id = a.id)
union all
select * from b
If the number, types, or order of columns differs you will need to explicitly specify the columns to return in each sub query.
I want to insert into a specific column in my table A which belongs to DB 1
from my DB 2 table B
In table A I have a unique ID field called F6 same goes for table B field name F68; both fields are the same they are simply a copy of each other which gives me the opportunity to do a join on them.
So far so good, what I want now is to insert into my table A in the field F110 the values from table B F64 since I did a join on the "ID's" they should be in the right manner.
All fields are of type VARCHAR.
INSERT INTO [D061_15018659].[dbo].[A](F110)
SELECT v.F64,v.F68
FROM [VFM6010061V960P].[dbo].[B] v LEFT JOIN
ON v.F68 = F6
I have the problem that I have an error on "ON" why so ever I can't figure it out.
Your select query provide 2 columns ==> you need concatenate the columns
You need repeat the tabel A in join clause.
Try this :
INSERT INTO [D061_15018659].[dbo].[A] (F110)
SELECT
v.F64 || v.F68 as theNewF110
FROM
[VFM6010061V960P].[dbo].[B] v
LEFT JOIN
[D061_15018659].[dbo].[A] w ON v.F68 = w.F6
So on this question, I'm having trouble.
EMPLOYEE(fname,minit,lname,ssn,birthdate,address,sex,salary,superssn,dno) key:ssn
DEPARTMENT(dname,dnumber,mgrssn,mgrstartdate) key:dnumber
PROJECT(pname,pnumber,plocation,dnum) key:pnumber
Here is what I wrote:
Select e.ssn, e.lname,e.fname,
From employee e,
where e.ssn in
(select s.ssn, s.lname,sfname
from employee s,
where s.superssn = e.ssn, AND s.lnamme='Wallace' s.fname ='Jennifer'
)
But I only got 10 out of 15 points, my professor said my select s.ssn,slname part is wrong, and it must "match my e.ssn". How should I fix this?
A self-join (same table). Alias e is for the worker, alias s is for the supervisor.
select s.ssn, s.lname,s.fname,
From employee s
join employee e
on s.ssn=e.superssn
where e.lname='Wallace' and e.fname ='Jennifer'
your in statement is going to make this query slow. you can refactor it to be a self join like so
select e.ssn, e.lname, e.fname
from employee e
join employee s on s.superssn = e.ssn
where s.lnamme='Wallace' AND s.fname ='Jennifer';
the problem with your in statement is you are making a dependent subquery which checks every row in the employee table with every row in the same table.
to break down the query itself
select s.ssn, s.lname, s.fname -- s is the supervisor
from employee e -- e is jennifer
join employee s on s.superssn = e.ssn -- self join on the supervisors id is equal to the employees id
where e.lnamme='Wallace' AND e.fname ='Jennifer';
Using IN is fine, but with a correlated subquery, EXISTS is the way to go:
Select s.ssn, s.lname, s.fname
From employee s
where exists (select 1
from employee e
where e.superssn = s.ssn AND
e.lname = 'Wallace' AND
e.fname = 'Jennifer'
);
Note:
The s and e are swapped. You want the supervisor information, so it goes in the outer query.
The extraneous commas have been removed.
AND has been added.
Using IN, it looks like:
Select s.ssn, s.lname, s.fname
From employee s
where s.ssn IN (select e.superssn
from employee e
where e.lname = 'Wallace' AND
e.fname = 'Jennifer'
);
Note that the correlation clause is not needed.
I've got two tables in my database. One of them, 'orders', contains a set of columns with an integer which represents what the order should contain (like 5 of A and 15 of B). The second table, 'production_work', contains those same order columns, and a date, so whenever somebody completes part of an order, I track it.
So now i need a fast way to know which orders are completed, and I'm hoping to avoid a 'completed' table on the first column as orders are editable and it's just more logic to keep correct.
This query works, but it's horribly written. What's a better way to do this? There are actually 12 of these columns that go into this query...I'm just showing 3 of them for the example.
SELECT *
FROM orders o
WHERE ud = (SELECT SUM(ud) FROM production_work WHERE order_id = o.ident)
AND dp = (SELECT SUM(dp) FROM production_work WHERE order_id = o.ident)
AND swrv = (SELECT SUM(swrv) FROM production_work WHERE order_id = o.ident)
select o.*
from
orders o
inner join
(
select order_id, sum(ud) as ud, sum(dp) as dp, sum(swrv) as swrv
from production_work
group by order_id
) pw on o.ident = pw.order_id
where
o.ud = pw.ud
and o.dp = pw.dp
and o.swrv = pw.swrv