SQL Server 2008: complex Insert - sql

Question

I have a table called Employees:
BeginYear | EndYear | Name
1974 1983 Robert
For each record in Employees I need to insert each year into a new table called EmployeeYears
So:
For Each Record in Employees
For i as int = Begin Year to End year
INSERT i, Name into EmployeeYears
Any Way to do this in SQL...possibly with cursors?

Answer 1

The gist of it is using a WITH statement to create all the records and use them to insert into your final table.
;WITH q AS (
SELECT Year = BeginYear
, Name
FROM Employees
UNION ALL
SELECT q.Year + 1
, q.Name
FROM q
INNER JOIN Employees e ON e.Name = q.Name
AND e.EndYear > q.Year
)
INSERT INTO EmployeeYears
SELECT * FROM q
OPTION(MAXRECURSION 0)
Testdata
CREATE TABLE Employees (BeginYear INTEGER, EndYear INTEGER, Name VARCHAR(32))
CREATE TABLE EmployeeYears (Year INTEGER, Name VARCHAR(32))
INSERT INTO Employees
SELECT 1974, 1976, 'Robert'
UNION ALL SELECT 1972, 1975, 'Lieven'
Results
SELECT *
FROM EmployeeYears
ORDER BY Name, Year
1972 Lieven
1973 Lieven
1974 Lieven
1975 Lieven
1974 Robert
1975 Robert
1976 Robert

Answer 2

If you have a numbers table you can join on it to get the individual year records and avoid using a cursor. I just poulated the numbers table with number from 1965 to 968, but a realife numbers table (which also would not be a temp table as shown below for example purposes, but one that lives in your schema) would probably have several million records as it is useful for a lot of comparing.
create table #Numbers (Number int)
insert into #Numbers
select 1965
union
select 1966
union
select 1967
union
select 1968
create table #employees (name varchar (50), beginyear int, endyear int)
insert into #employees
select 'Dick', 1966, 1968
union all
select 'harry', 1965, 1967
union all
select 'tom', 1955, 1966
insert into EmployeeYears (Name, [Year])
select Name, n.number
from #Employees e
join #Numbers n on n.number between e.beginyear and e.endyear
order by name

Answer 3

Yes, you actually have to do a loop... I'd prefer not using CURSORS, but this case sorta makes sense... anyway, here's the code as just a straight loop to show you that you can do that kind of code in SQL:
DECLARE #Employee VARCHAR(100)
DECLARE #BeginYear INT, #EndYear INT, #i INT
SET #Employee = ''
WHILE (1=1)
BEGIN
SET #Employee = (SELECT TOP 1 Name FROM Employees ORDER BY Name WHERE Name > #Employee)
IF #Employee IS NULL BREAK
SELECT #BeginYear = BeginYear, #EndYear = EndYear FROM Employees WHERE Name = #Employee
SET #i = #BeginYear
WHILE (#i <= #EndYear)
BEGIN
INSERT INTO EmployeeYears (Year, Name) VALUES (#i, #Employee)
SET #i = #i + 1
END
END

Answer 4

You can use a recursive CTE:
;WITH CTE AS
(
SELECT BeginYear, EndYear, Name
FROM Employees
UNION ALL
SELECT BeginYear+1, EndYear, Name
FROM CTE
WHERE BeginYear < EndYear
)
INSERT INTO EmployeeYears (Year, Name)
SELECT BeginYear, Name
FROM CTE
ORDER BY Name, BeginYear
OPTION(MAXRECURSION 0)

Answer 5

You can use a recursive procedure. Llike the one bellow:
CREATE Procedure InsertYear
#Name ....
#BeginYear ...
#EndYear ...
AS
{
INSERT INTO EmployeeYears VALUES(#BeginYear, #Name);
SET #BeginYear = #BeginYear + 1
IF #BeginYear < #EndYear
BEGIN
InsertYear(#Name, #BeginYear, #EndYear)
END
RETURN
}

Answer 6

You could do this but it will fail if Begin or end exceeds 2047
INSERT INTO EmployeeYears (number, name)
SELECT v.number, e.name
FROM
Employees e
INNER JOIN master..spt_values v on
v.number between beginYear and endYear