Please check fiddle: myFiddle
Query:
create table Emp(empId int primary key, EmpName varchar(50),MngrID int)
insert into Emp(empId,EmpName,MngrID)values(1,'A',2)
insert into Emp(empId,EmpName,MngrID)values(2,'B',null)
A has mngr B but A has no mngr, so while fetching the record from query it shows me:
EmpId EmpName MngrName(alias MngrName)
1 A B
2 B null
How to fetch the above data using a query?
For some reason it doesn't work in SQLFiddle, but i ran it in my own instance of SQL Server to verify it does work:
SELECT e1.EmpID, e1.EmpName, e2.EmpName
FROM emp e1 LEFT OUTER JOIN emp e2
ON e1.MngrID = e2.EmpID
Basically, you're doing a 'self join' by declaring two instances of the table (e1 and e2), and then joining the first instance's MngrID to the second instance's EmpID.
You need to LEFT JOIN table to itself:
select A.empID, A.empName, b.empName as mgrName
from emp A left join emp B on A.mngrID = b.empID
http://sqlfiddle.com/#!3/184dc/8
select empId,EmpName,(SELECT EmpName FROM emp WHERE MngrID = amp1.MngrID) AS Manager from emp as amp1
Related
I need help with query for sql developer.The requirement is a select statement which returns ID Column.I need to hold this ids in a variable and fetch the records associated with each id.Thanks for any help.
You can use join statement.
for example:
select id from table_1 join table_2
on table_1.id = table_2.id;
Not possible, as far as I can tell.
But, if it is the same query all over again and you use its result (those ID values you mentioned) in another queries, then you could create a view
create or replace view v_id as
select id
from some_table
where some_conditions;
and then use that view as yet another data source, e.g.
select d.dname, e.ename, e.job, e.sal
from emp e join v_id v on v.id = e.empno
join dept d on d.deptno = e.deptno;
or
select e.ename, e.job, e.sal
from emp e
where e.empno in (select v.id from v_id v);
or any other option you might choose.
I have three tables (example) STAFF, STU, EMP.
I want to combine the column EMPID in table STAFF and table EMP into 1 column?
My previous query is like this,
SELECT *
FROM STU s
FULL OUTER JOIN STAFF st ON st.STAFFID = STUID
FULL OUTER JOIN EMP e ON s.STUID = st.EMPID
The result is like this
The expected result is just like the above screenshot, but I want to join EMPID into one column only.
UPDATE:
I tried using this query:
SELECT
stu.stuid, stu.stuname, stu.stucode,
s.staffid, s.staffname, s.staffcode,
emp.empname, emp.empcode,
COALESCE (emp.empid, staff.staffid) AS col
FROM
STU, Staff, EMP
FULL OUTER JOIN
STAFF s ON s.STAFFID = stu.STUID
FULL OUTER JOIN
EMP e ON stu.STUID = s.EMPID
but it displays an error like this
Use below query to get the desired result.
SELECT s.StuID, s.StuName, s.Stucode, st.StaffId, st.StaffName, st.Staffcode, isnull(st.EmpId, e.EmpId) EmpId, e.EmpCode, e.EmpName
FROM STU s FULL outer JOIN
STAFF st
ON st.STAFFID = STUID FULL OUTER JOIN
EMP e
ON s.STUID = st.EMPID
Note: You will get the one emp Id column as needed. If Staff emp id is not null then staff emp id will be displayed else employee emp id will be displayed
i want insert date from table to other
with 2 condition from same row
(view picture in yellow part)
thanks
The problem is that the IN in the where clause can only have one colymn, not two. You could re-write it as:
from emp e
inner join emp2 e2 on e.Id = e2.Id and e.storeId = e2.storeId
I think that this would get you the effect.
You can declare only one field in "not in subselect" approach.
You should give this workaround a try:
select .... from emp e
where not exists (
select 1 from emp2 e2 where e.id = e2.id and e.storeid = e2.storeid
)
I guess it provides exactly the same result as you need
I am trying to convert the following query:
select *
from employees
where emp_id not in (select distinct emp_id from managers);
into a form where I represent the subquery as a join. I tried doing:
select *
from employees a, (select distinct emp_id from managers) b
where a.emp_id!=b.emp_id;
I also tried:
select *
from employees a, (select distinct emp_id from managers) b
where a.emp_id not in b.emp_id;
But it does not give the same result. I have tried the 'INNER JOIN' syntax as well, but to no avail. I have become frustrated with this seemingly simple problem. Any help would be appreciated.
Assume employee Data set of
Emp_ID
1
2
3
4
5
6
7
Assume Manger data set of
Emp_ID
1
2
3
4
5
8
9
select *
from employees
where emp_id not in (select distinct emp_id from managers);
The above isn't joining tables so no Cartesian product is generated... you just have 7 records you're looking at...
The above would result in 6 and 7 Why? only 6 and 7 from Employee Data isn't in the managers table. 8,9 in managers is ignored as you're only returning data from employee.
select *
from employees a, (select distinct emp_id from managers) b
where a.emp_id!=b.emp_id;
The above didnt' work because a Cartesian product is generated... All of Employee to all of Manager (assuming 7 records in each table 7*7=49)
so instead of just evaluating the employee data like you were in the first query. Now you also evaluate all managers to all employees
so Select * results in
1,1
1,2
1,3
1,4
1,5
1,8
1,9
2,1
2,2...
Less the where clause matches...
so 7*7-7 or 42. and while this may be the answer to the life universe and everything in it, it's not what you wanted.
I also tried:
select *
from employees a, (select distinct emp_id from managers) b
where a.emp_id not in b.emp_id;
Again a Cartesian... All of Employee to ALL OF Managers
So this is why a left join works
SELECT e.*
FROM employees e
LEFT OUTER JOIN managers m
on e.emp_id = m.emp_id
WHERE m.emp_id is null
This says join on ID first... so don't generate a Cartesian but actually join on a value to limit the results. but since it's a LEFT join return EVERYTHING from the LEFT table (employee) and only those that match from manager.
so in our example would be returned as e.emp_Di = m.Emp_ID
1,1
2,2
3,3
4,4
5,5
6,NULL
7,NULL
now the where clause so
6,Null
7,NULL are retained...
older ansii SQL standards for left joins would have been *= in the where clause...
select *
from employees a, managers b
where a.emp_id *= b.emp_id --I never remember if the * is the LEFT so it may be =*
and b.emp_ID is null;
But I find this notation harder to read as the join can get mixed in with the other limiting criteria...
Try this:
select e.*
from employees e
left join managers m on e.emp_id = m.emp_id
where m.emp_id is null
This will join the two tables. Then we discard all rows where we found a matching manager and are left with employees who aren't managers.
Your best bet would probably be a left join:
select
e.*
from employees e
left join managers m on e.emp_id = m.emp_id
where
m.emp_id is null;
The idea here is you're saying that you want to select everything from employees, including anything that matches in the manager table based on emp_id and then filtering out the rows that actually have something in the manager table.
Use Left Outer Join instead
select e.*
from employees e
left outer join managers m
on e.emp_id = m.emp_id
where m.emp_id is null
left outer join will preserve the rows from m table even if they do not have a match i e table based on the emp_id field. The we filter on where m.emp_id is null - give me all the rows from e where there's no matching record in m table.
A bit more on the subject can be found here:
Visual representation of joins
from employees a, (select distinct emp_id from managers) b implies cross join - all posible combinations between tables (and you needed left outer join instead)
The MINUS keyword should do the trick:
SELECT e.* FROM employees e
MINUS
Select m.* FROM managers m
Hope that helps...
select *
from employees
where Not (emp_id in (select distinct emp_id from managers));
I have a table of employees that are formatted as follows:
EMPLOYEE (FNAME,MINIT,LNAME,SSN(PK),BDATE,SUPERSSN(NULLABLE))
I need to query every employee and retrieve the following information:
FNAME(employee),LNAME(employee),SUPERSSN,(super)FNAME,(super)LNAME
UPDATED
After running this query:
SELECT A.FNAME,A.LNAME,A.SUPERSSN,B.FNAME,B.LNAME
FROM EMPLOYEE
A LEFT JOIN EMPLOYEE B
ON A.SUPERSSN = B.SSN;
The results were close, but when the superssn was null (CEO/Boss) it caused the remaining rows to populate as null also and did not populate with the actual supervisors ssn. I'm trying to use an IF statement to fix the problem with having a SuperSSN that is null, but I'm receiving the error: ORA-00905: missing keyword.
Below is the query that I ran that generated the error.
SELECT A.FNAME,A.LNAME,A.SUPERSSN,B.FNAME,B.LNAME
FROM EMPLOYEE A LEFT IF A.SUPERSSN <> 'NULL'
JOIN EMPLOYEE B ON A.SUPERSSN = B.SSN;
Select A.FName,
A.LNAme,
A.SuperSSN,
B.FName,
B.LName
from Employee A
Left Join Employee B
On A.SuperSSN = B.SSN