combining codes in one anonymous block - sql

Question

I need some help in combining my three codes in one anonymous block and also I need to put a substitution value that a user will use. any idea how I can do that ?? I am using oracle 10g express, here are my codes:
CODE 1: Display department name and number of employees per department for every department that is in "Americas".
select department_name, count(employee_id) "number of employees"
from employees, departments, locations, countries, regions
where employees.DEPARTMENT_ID = departments.DEPARTMENT_ID
AND departments.location_ID = locations.location_ID
AND locations.country_ID = countries.country_ID
AND countries.region_ID = regions.region_ID
AND regions.region_name = 'Americas'
group by department_name
CODE 2: What are the average salaries per position?
SELECT job_ID, AVG(salary) as "avg salary"
FROM employees
GROUP BY job_ID
CODE 3:What are the average salaries per department?
SELECT department_ID, AVG(salary) as "avg salary"
FROM employees
GROUP BY department_ID

Answer 1

Combining completely different datasets into a single block is not possible in Oracle. Anonymous blocks are for executing a series of PL/SQL commands. A query (i.e. anything that returns back a result set, ex: SELECT ...)can only return a single result so it would need to be three separate queries.
If you're using SQL*Plus all of this can be done from the command line and/or with a .sqlscript file. You can also specify parameters on the command line as well (I couldn't tell if thats what you meant for the first query but I added it anyway).
Script (foo.sql):
-- Set page size to something larger than the expected result set.
-- NOTE: You don't want to put 0 (unlimited) as it supresses the column headers.
SET pagesize 50000
-- Get the parameter from the command line:
VAR region VARCHAR2(256)
EXEC :region := '&1'
SELECT 'Processing for region: ' || :region
FROM dual;
-- Query 1
promp "Employee detail in specified region:"
select department_name, count(employee_id) "number of employees"
from HR.employees, HR.departments, HR.locations, HR.countries, HR.regions
where employees.DEPARTMENT_ID = departments.DEPARTMENT_ID
AND departments.location_ID = locations.location_ID
AND locations.country_ID = countries.country_ID
AND countries.region_ID = regions.region_ID
AND regions.region_name = :region
group by department_name
;
-- Query 2:
promp "Average salary by position:"
SELECT job_ID, AVG(salary) as "avg salary"
FROM HR.employees
GROUP BY job_ID;
-- Query 3:
promp "Average salaries by department:"
SELECT department_ID, AVG(salary) as "avg salary"
FROM HR.employees
GROUP BY department_ID;
exit
Output:
$ sqlplus myuser/mypass#lvm01xe #sample.sql Americas
SQL*Plus: Release 11.2.0.2.0 Production on Sun Nov 18 09:11:11 2012
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
PL/SQL procedure successfully completed.
'PROCESSINGFORREGION:'||:REGION
--------------------------------------------------------------------------------
Processing for region: Americas
"Employee detail in specified region:"
DEPARTMENT_NAME number of employees
------------------------------ -------------------
Administration 1
Accounting 2
IT 5
Purchasing 6
Executive 3
Shipping 45
Finance 6
Marketing 2
8 rows selected.
"Average salary by position:"
JOB_ID avg salary
---------- ----------
IT_PROG 5760
AC_MGR 12000
AC_ACCOUNT 8300
ST_MAN 7280
PU_MAN 11000
AD_ASST 4400
AD_VP 17000
SH_CLERK 3215
FI_ACCOUNT 7920
FI_MGR 12000
PU_CLERK 2780
SA_MAN 12200
MK_MAN 13000
PR_REP 10000
AD_PRES 24000
SA_REP 8350
MK_REP 6000
ST_CLERK 2785
HR_REP 6500
19 rows selected.
"Average salaries by department:"
DEPARTMENT_ID avg salary
------------- ----------
100 8600
30 4150
7000
90 19333.3333
20 9500
70 10000
110 10150
50 3475.55556
80 8955.88235
40 6500
60 5760
10 4400
12 rows selected.
Disconnected from Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production

Answer 2

Obviously, anything which is aggregated by the same yardstick can be combined easily. Hence you can merge the third query with your first one like this:
select department_name
, count(employee_id) as "number of employees"
, avg(salary) as "avg salary"
from employees, departments, locations, countries, regions
where employees.DEPARTMENT_ID = departments.DEPARTMENT_ID
AND departments.location_ID = locations.location_ID
AND locations.country_ID = countries.country_ID
AND countries.region_ID = regions.region_ID
AND regions.region_name = :region_name
group by department_name
I have adapted your code to pass in a bind variable, :region_name. There are various way of specifying variables in Apex. Find out more.
There is no meaningful way of including your second query. The values for JOB_ID cross the values of DEPARTMENT_ID, so there's no common key to join on.