The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • My Flickr Stream

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,929 other followers

Archive for August 28th, 2019

Structure and Interpretation of Test Cases : Kevlin Henney on Vimeo

Posted by jpluimers on 2019/08/28

Must watch when you do unit testing (no matter the environment): [WayBackStructure and Interpretation of Test Cases : Kevlin Henney on Vimeo which he presented at Javazone 2018 [Archive.is]

via [WayBack] Kevlin Henney – Google+

–jeroen

Posted in Agile, Conference Topics, Conferences, Development, Event, Software Development, Unit Testing | Leave a Comment »

Passing multiple parameters to a Python method: the * tag

Posted by jpluimers on 2019/08/28

I had to pass parameters to a method so they became a list:

    threadManager.append(
        UrlMonitorThread(monitor, "http://%s" % targetHost),
        SmtpMonitorThread(monitor, targetHost, 25),
        SmtpMonitorThread(monitor, targetHost, 587),
        SshMonitorThread(monitor, targetHost, 22))

This appeared much easier than I anticipated:

    def append(self, *threads):
        for thread in threads:
            self.threads.append(thread)

It uses the * tag which is explained here:

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

Counting rows for all tables in Firebird

Posted by jpluimers on 2019/08/28

Sometimes you want to count data in all tables on a database to get a feel for the orders of magnitude, but you cannot use the approximated example in How to speed up Count(*) in Interbase/Firebird – Stack Overflow as those require primary keys.

Then the below script can help: it generates the right queries as a union all ordering by the count in the tables.

Example generated code on C:\Program Files (x86)\Firebird\Firebird_2_5\examples\empbuild\EMPLOYEE.FDB:

SQL
--------------------------------------------------------------------------------------------------
select 128 as id, 'COUNTRY' as name, count(*) from "COUNTRY" union all
select 129 as id, 'JOB' as name, count(*) from "JOB" union all
select 130 as id, 'DEPARTMENT' as name, count(*) from "DEPARTMENT" union all
select 131 as id, 'EMPLOYEE' as name, count(*) from "EMPLOYEE" union all
select 133 as id, 'PROJECT' as name, count(*) from "PROJECT" union all
select 134 as id, 'EMPLOYEE_PROJECT' as name, count(*) from "EMPLOYEE_PROJECT" union all
select 135 as id, 'PROJ_DEPT_BUDGET' as name, count(*) from "PROJ_DEPT_BUDGET" union all
select 136 as id, 'SALARY_HISTORY' as name, count(*) from "SALARY_HISTORY" union all
select 137 as id, 'CUSTOMER' as name, count(*) from "CUSTOMER" union all
select 138 as id, 'SALES' as name, count(*) from "SALES" order by 3

Example output on C:\Program Files (x86)\Firebird\Firebird_2_5\examples\empbuild\EMPLOYEE.FDB:

ID NAME COUNT
133 PROJECT 6
128 COUNTRY 14
137 CUSTOMER 15
130 DEPARTMENT 21
135 PROJ_DEPT_BUDGET 24
134 EMPLOYEE_PROJECT 28
129 JOB 31
138 SALES 33
131 EMPLOYEE 42
136 SALARY_HISTORY 49

The generation code below uses a few tricks:

The rank helps me distinguish the last row (for the order by 3 clause) and other rows (for the union all clauses).

Generation code:

with tables(id, name) as (
    -- http://www.firebirdfaq.org/faq376/
    select r.RDB$RELATION_ID as id, trim(r.RDB$RELATION_NAME) as name
    from RDB$RELATIONS r
    where 1=1
      and (r.RDB$SYSTEM_FLAG is null or r.RDB$SYSTEM_FLAG = 0)
      and r.RDB$VIEW_BLR is null
    order by 1
  ),
  ranked_tables(id, rank, name) as ( 
    -- http://www.firebirdfaq.org/faq343/
    select tables.ID, count(others.id)+1 as "rank", tables.NAME
    from tables
    left join tables others on others.ID < tables.ID
    group by "ID", "NAME"
    order by "rank"
  ),
  parts(id, rank, name, suffix) as (
    select ranked_tables.id, 
            ranked_tables.rank,
            ranked_tables.name,
      case
        when ranked_tables.rank = 1 then 'union all' -- first 
        when ranked_tables.rank = (select count(*) from tables) then 'order by 3' --last 
        else 'union all' -- middle
      end as suffix      
    from ranked_tables 
  ) 
select -- parts.id, parts.rank, parts.name, parts.suffix,
       'select '||parts.id||' as id, '''||parts.name||''' as name, count(*) from "'||parts.name||'" '||parts.suffix||'' as SQL
from parts
order by parts.id

–jeroen

Read the rest of this entry »

Posted in Database Development, Development, Firebird, Software Development, SQL | Leave a Comment »

 
%d bloggers like this: