I have two tables:
table_a
id name
1 john
2 dave
3 tim
4 marta
5 jim
table_b
id sum random_metric
1 10.50 abc
3 11.5 efg
5 5.76 ghj
I have joined them on id
SELECT ...
FROM table_a
LEFT JOIN table_b ON table_a.id = table_b.id
and I get:
id name sum random_metric
1 john 10.5 abc
2 dave
3 tim 11.5 efg
4 marta
5 jim 5.76 ghj
Then I want to convert the sum column to double precision but since it has empty strings in rows 2, 4 it does not work.
How could I join tables so that I would have this:
id name sum random_metric
1 john 10.5 abc
2 dave NULL NULL
3 tim 11.5 efg
4 marta NULL NULL
5 jim 5.76 ghj
I have been asked to generate a report to show the number of occurrences an employee is absent from work sick.
If an employee is absent from work for 3 consecutive days this will be counted as 1 occurrence. If they then return to work and are then absent again for another 2 consecutive days this will be recorded as 2 occurrences.
I need to generate a report to show the number of occurrences an employee is away from work sick within a 6 month period.
I have set out an example below of the data showing an employee's absence records and how i need the report to look.
How data shows in database:
enter image description here
Name Absence Dates
John Smith 01-Sep-19
John Smith 02-Sep-19
John Smith 03-Sep-19
John Smith 10-Sep-19
John Smith 11-Sep-19
How i wish for the report to look:
Name Occurrences
John Smith 2
I would be grateful for any assistance with writing to code to achieve this result.
Not a full answer, as you should really do some of this yourself, however, based on what you have detailed in your quesiton, you could use the approach below to count up any spells of absence, within a 6 month period.
Assumes you would be compiling this using SQL Server
declare #absences table (empid nvarchar(10), [abs date] date, [ret date] date);
declare #staff table ([empid] int, [name1] nvarchar(50), [name2] nvarchar(50), [surname] nvarchar(50));
-- put some test values in the staff table to work with
insert into #staff
values
(1, 'John', 'Lewis', 'Smith'), -- using a unique ID here, in any good system this should be an incremental number for each new staff member added to the table
(2, 'James', 'Thomas', 'Brown')
-- put some test values in the absences table to work with
insert into #absences
values
(1, '2019-07-01', '2019-07-04'), -- userid, absence date & return date
(1, '2019-08-04', '2019-08-06'),
(2, '2019-07-02', '2019-07-05'),
(2, '2019-08-05', '2019-08-07')
select count(*) spellsoff, empid, name1, name2, surname, [days absent]
from
(
select
s.empid,
s.name1,
s.name2,
s.surname,
a.[abs date],
a.[ret date],
datediff(d,a.[abs date], a.[ret date]) [days absent]
from #staff s
left join #absences a
on s.empid = a.empid
where [abs date] >= DATEADD(M,-6,GETDATE()) -- pull back those employeess that have been absent in the last 6 months from today's date
)doff
group by empid, name1, name2, surname, [days absent]
Gives you the following breakdown:
spellsoff empid name1 name2 surname days absent
1 1 John Lewis Smith 2
1 1 John Lewis Smith 3
1 2 James Thomas Brown 2
1 2 James Thomas Brown 3
This question already has answers here:
Left Outer Join Not Working?
(4 answers)
Closed 4 years ago.
I've created a table of students with columns student_id as primary key,
student_name and gender.
I've an another table gender which consists of gender_id and gender.
gender_id in student refers to table gender.
Tables data looks like this:
Student table
STUDENT_ID STUDENT_NAME GENDER
1 Ajith 1
2 Alan 1
3 Ann 2
4 Alexa 2
5 Amith 1
6 Nisha 2
7 Rathan 1
8 Rebecca 2
9 asdf null
10 asd null
11 dbss null
Gender Table
GENDER_ID GENDER
1 Male
2 Female
3 Others
My query and its result
SELECT S.STUDENT_NAME,
G.GENDER
FROM STUDENTS S
FULL OUTER JOIN GENDER G ON G.GENDER_ID = S.GENDER
result is giving with 12 rows including the Others value from the gender table.
STUDENT_ID STUDENT_NAME GENDER
1 Ajith Male
2 Alan Male
3 Ann Female
4 Alexa Female
5 Amith Male
6 Nisha Female
7 Rathan Male
8 Rebecca Female
Others
9 asdf
10 asd
11 dbss
I'm trying to restrict a particular student_id:
SELECT S.STUDENT_ID,
S.STUDENT_NAME,
G.GENDER
FROM STUDENTS S
FULL OUTER JOIN GENDER G ON G.GENDER_ID = S.GENDER
WHERE S.STUDENT_ID <> 11;
now the the total number of the rows are reduced to 10.
STUDENT_ID STUDENT_NAME GENDER
1 Ajith Male
2 Alan Male
3 Ann Female
4 Alexa Female
5 Amith Male
6 Nisha Female
7 Rathan Male
8 Rebecca Female
9 asdf
10 asd
Why has the one row with Others Values disappeared from the second select query?
I'm trying to find the cause of this issue.
That's because NULL <> 11 is not TRUE, but NULL, and only rows where the condition is TRUE are included in the result.
You'd have to write something like
WHERE s.student_id IS DISTINCT FROM 11
Your second select query returns all rows where student_id is different (<>) from 11.
I have a table which holds data in the following format, however I would like to be able to create a query that checks whether the reference number is duplicated and only return the entry with the latest date_issued.
ref_no name gender place date_issued
xgb/358632/p John Smith M London 02.08.2016
Xgb/358632/p John Smith M London 14.06.2017
Rtu/638932/k Jane Doe F Birmingham 04.09.2017
The result from the query should be;
ref_no name gender place date_issued
Xgb/358632/p John Smith M London 14.06.2017
Rtu/638932/k Jane Doe F Birmingham 04.09.2017
Is there a fairly straightforward solution for this?
assuming the date column is type date or timestamp
select distinct on(ref_no) * from tablename order by refno,date desc;
this works beacuse distinct on supresses rows with duplicates of the expression in parenthese.
In my Table 1, It may have AND have a null entry in the address column to corresponding record OR not have a matching entry in Table 2.
I want to present all the records in Table 1 but also present corresponding entries from Table 2. My RESULT is what I am trying to achieve.
Table 1
ID First Last
1 John Smith
2 Bob Long
3 Bill Davis
4 Sam Bird
5 Tom Fenton
6 Mary Willis
Table 2
RefID ID Address
1 1 123 Main
2 2 555 Center
3 3 626 Smith
4 4 412 Walnut
5 1
6 2 555 Center
7 3
8 4 412 Walnut
Result
Id First Last Address
1 John Smith 123 Main
2 Bob Long 555 Center
3 Bill Davis 626 Smith
4 Sam Bird 412 Walnut
5 Tom Fenton
6 Mary Willis
You need an outer join for this:
SELECT * FROM Table1 t1 LEFT OUTER JOIN Table2 t2 ON t1.ID = t2.RefID
How do you join those two tables? If table 2 have more than 1 matched address, how do you want display them? Please clarify in your question.
Here is a query based on my assumptions.
SELECT
ID, First, Last,
Address = (SELECT MAX(Address) FROM Table2 t2 WHERE t1.ID = t2.ID)
FROM Table1 t1