For my link archive:
- [WayBack] delphi – How to enable wirecompression on Firebird 3.0 – Stack Overflow
- [WayBack] delphi – How to enable WireCompression on Firebird 3.0 using FireDAC – Stack Overflow
–jeroen
Archive for the ‘Firebird’ Category
delphi – How to enable wirecompression on Firebird 3.0 – Stack Overflow
Posted by jpluimers on 2021/07/08
Posted in Database Development, Delphi, Development, Firebird, Software Development | Leave a Comment »
FireDAC can do DBMS back-end conditional SQL via Conditional Substitution
Posted by jpluimers on 2020/09/17
Though the field-types mentioned in the problem and solution are equal (so either is wrong), the solution in [WayBack] I have a little problem with FireDAC and the TStringField and TWideStringField design time generation… – Juan C. Cilleruelo – Google+ pointed out by Jeff Weir is interesting: FireDAC supports conditionals that depend on the DBMS back-end, so you can differentiate between them.
The feature is called Conditional Substitution and has been present ever since AnyDAC (which got bought by Embarcadero, transformed into FireDAC, then after Idera bought Embarcadero, the main developer got pink-slipped).
The AnyDAC documentation is in the wayback machine, though you have to disable the onload event in order to read it.
The [Archive.is] XE5: Preprocessing Command Text (FireDAC) – RAD Studio documentation is not much different from the current state [Archive.is].
More background reading is at [WayBack] www.freepascal.org/~michael/articles/anydac2/anydac2.pdf and Cary Jensen covered it in his 2017 course on FireDAC of which you can see the free ToC.
Example from that thread:
SELECT ART.CD_ITEM ,
ART.CD_FAMILY ,
ART.CD_CATALOGUE ,
CAT.DS_CATALOGUE ,
FAM.DS_FAMILY ,
{IF MSSQL}
CASE WHEN EXISTS(SELECT 1 FROM CONFIGURATIONS COM WHERE COM.CD_PARENT = ART.CD_ITEM)
THEN CAST('Y' AS NVARCHAR)
ELSE CAST('N' AS NVARCHAR)
END HAS_CONFIGURATION ,
{fi}
{IF FIREBIRD}
CASE WHEN EXISTS(SELECT 1 FROM CONFIGURATIONS COM WHERE COM.CD_PARENT = ART.CD_ITEM)
THEN 'Y'
ELSE 'N'
END HAS_CONFIGURATION ,
{fi}
ART.DS_ITEM ,
ART.CD_TAX ,
TAX.DS_TAX ,
TAX.PRC_TAX ,
...
Given the problem statement, the casts likely should have been VARCHAR instead of NVARCHAR, but the construct can be very powerful.
–jeroen
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Firebird: RDB$RELATIONS.RDB$RELATION_TYPE and when it can be null
Posted by jpluimers on 2019/09/11
The RDB$RELATIONS.RDB$RELATION_TYPE was introduced in Firebird 2.1 with these enumeration values:
enum rel_t {
rel_persistent = 0,
rel_view = 1,
rel_external = 2,
rel_virtual = 3,
rel_global_temp_preserve = 4,
rel_global_temp_delete = 5
};
You should access it assuming NULL means zero (0), so you better treat it using [WayBack] COALESCE() like COALESCE(RDB$RELATIONS.RDB$RELATION_TYPE, 0).
Background information:
- [WayBack] Under what condition can RDB$RELATION_TYPE be NULL?
- [WayBack] When restoring ODS 11.1 or older databases under Firebird 2.5 or Firebird 3 the RDB$RELATION_TYPE can remain null.
- [WayBack] Заполнение RDB$RELATIONS.RDB$RELATION TYPE translated:
FillingRDB$RELATIONS.RDB$RELATION TYPE
It seems that 2.5.1 when restoring backup 2.0 fills the saber field with NULL instead of zero for normal user tables. Can anyone confirm this behavior before I get into the tracker?
–jeroen
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Firebird 3.x SQL Language Changes
Posted by jpluimers on 2019/09/05
Since I likely need these [WayBack] SQL Language Changes in the future (some breaking Firebird 2.x habits).
The odd thing is that I got there looking for “no column name specified for column number 1 in derived table” when doing some weird CTE query things in Firebird 2.5x
–jeroen
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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:
- [WayBack] How to get record count for all tables? and [WayBack] How to get a list of tables, views and columns in Firebird database?
Here’s query to list all user tables:
select rdb$relation_name
from rdb$relations
where rdb$view_blr is null
and (rdb$system_flag is null or rdb$system_flag = 0); - [WayBack] How to get record number or rank as part of dataset? (note that
IDthe negation ofSCORE)
The RANK of a row is simply the COUNT() + 1 of better-ranked rows. This can be computed with a
self-join:
SELECT p.name, p.score, COUNT(others.score) + 1 AS "rank"
FROM players p
LEFT JOIN players others ON others.score > p.score
GROUP BY 1, 2
ORDER BY "rank"
The rank helps me distinguish the last row (for the order by 3 clause) and other rows (for the union all clauses).
Generation code:
with tables(id, name) as (
-- http://www.firebirdfaq.org/faq376/
select r.RDB$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
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