I'm searching a way to simulate "create table as select" in Firebird from SP.
We are using this statement frequently in another product, because it is very easy for make lesser, indexable sets, and provide very fast results in server side.
create temp table a select * from xxx where ...
create indexes on a ...
create temp table b select * from xxx where ...
create indexes on b ...
select * from a
union
select * from b
Or to avoid the three or more levels in subqueries.
select *
from a where id in (select id
from b
where ... and id in (select id from c where))
The "create table as select" is very good cos it's provide correct field types and names so I don't need to predefine them.
I can simulate "create table as" in Firebird with Delphi as:
Make select with no rows, get the table field types, convert them to create table SQL, run it, and make "insert into temp table " + selectsql with rows (without order by).
It's ok.
But can I create same thing in a common stored procedure which gets a select sql, and creates a new temp table with the result?
So: can I get query result's field types to I can create field creator SQL from them?
I'm just asking if is there a way or not (then I MUST specify the columns).
Executing DDL inside stored procedure is not supported by Firebird. You could do it using EXECUTE STATEMENT but it is not recommended (see the warning in the end of "No data returned" topic).
One way to do have your "temporary sets" would be to use (transaction-level) Global Temporary Table. Create the GTT as part of the database, with correct datatypes but without constraints (those would probably get into way when you fill only some columns, not all) - then each transaction only sees it's own version of the table and data...
Related
Consider an enterprise that captures sensor data for different production facilities. per facility, we create an aggregation query that averages the values to 5min timeslots. This query exists out of a long list of with-clauses and writes data to a table (called aggregation_table).
Now my problem: currently we have n queries running that exactly run the same logic, the only thing that differs are table names (and sometimes column names but let's ignore that for now).
Instead of managing n different scripts that are basically the same, I would like to put it in a stored procedure that is able to work like this:
CALL aggregation_query(facility_name) -> resolve the different tables for that facility and then use them in the different with clauses
On top of that, instead of having this long set of clauses that give me the end-result, I would like to chunk them up in logical blocks that are parametrizable, So for example, if I call the aforementioned stored_procedure for facility A, I want to be able to pass / use this table name in these different functions, where the output can be re-used in the next statement (like you would do with with clauses).
Another argument of why I want to chunk this up in re-usable blocks is because we have many "derivatives" on this aggregation query, for example to manage historical data, to correct data or to have the sensor data on another aggregation level. As these become overly complex, it is much easier to manage them without having to copy paste and adjust these every time.
In the current set-up, it could be useful to know that I am only entitled to use plain BigQuery, As my team is not allowed to access the CI/CD / scheduling and repository. (meaning that I cannot solve the issue by having CI/CD that deploys the n different versions of the procedure and functions)
So in the end, I would like to end up with something like this using only bigquery:
CREATE OR REPLACE PROCEDURE
`aggregation_function`()
BEGIN
DECLARE
tablename STRING;
DECLARE
active_table_name STRING; ##get list OF tables CREATE TEMP TABLE tableNames AS
SELECT
table_catalog,
table_schema,
table_name
FROM
`catalog.schema.INFORMATION_SCHEMA.TABLES`
WHERE
table_name = tablename;
WHILE
(
SELECT
COUNT(*)
FROM
tableNames) >= 1 DO ##build dataset + TABLE name
SET
active_table_name = CONCAT('`',table_catalog,'.',table_schema,'.' ,table_name,'`'); ##use concat TO build string AND execute
EXECUTE IMMEDIATE '''
INSERT INTO
`aggregation_table_for_facility` (timeslot, sensor_name, AVG_VALUE )
WITH
STEP_1 AS (
SELECT
*
FROM
my_table_function_step_1(active_table_name,
parameter1,
parameter2) ),
STEP_2 AS (
SELECT
*
FROM
my_table_function_step_2(STEP_1,
parameter1,
parameter2) )
SELECT * FROM STEP_2
'''
USING active_table_name as active_table_name;
DELETE
FROM
tableNames
WHERE
table_name = tablename;
END WHILE
;
END
;
I was hoping someone could make a snippet on how I can do this in Standard SQL / Bigquery, so basically:
stored procedure that takes in a string variable and is able to use that as a table (partly solved in the approach above, but not sure if there are better ways)
(table) function that is able to take this table_name parameter as well and return back a table that can be used in the next with clause (or alternatively writes to a temp table)
I think below code snippets should provide you with some insights when dealing with procedures, inserts and execute immediate statements.
Here I'm creating a procedure which will insert values into a table that exists on the information schema. Also, as a value I want to return I use OUT active_table_name to return the value I assigned inside the procedure.
CREATE OR REPLACE PROCEDURE `project-id.dataset`.custom_function(tablename STRING,OUT active_table_name STRING)
BEGIN
DECLARE query STRING;
SET active_table_name= (SELECT CONCAT('`',table_catalog,'.',table_schema,'.' ,table_name,'`')
FROM `project-id.dataset.INFORMATION_SCHEMA.TABLES`
WHERE table_name = tablename);
#multine query can be handled by using ''' or """
Set query =
'''
insert into %s (string_field_0,string_field_1,string_field_2,string_field_3,string_field_4,int64_field_5)
with custom_query as (
select string_field_0,string_field_2,'169 BestCity',string_field_3,string_field_4,55677 from %s limit 1
)
select * from custom_query;
''';
# querys must perform operations and must be the last thing to perform
# pass parameters using format
execute immediate (format(query,active_table_name,active_table_name));
END
You can also use a loop to iterate trough records from a working table so it will execute the procedure and also be able to get the value from the procedure to use somewhere else.ie:A second procedure to perform a delete operation.
DECLARE tablename STRING;
DECLARE out_value STRING;
FOR record IN
(SELECT tablename from `my-project-id.dataset.table`)
DO
SET tablename = record.tablename;
LOOP
call `project-id.dataset`.custom_function(tablename,out_value);
select out_value;
END LOOP;
END FOR;
To recap, there are some restrictions such as the possibility to call procedures inside a execute immediate or to use execute immediate inside an execute immediate, to count a few. I think these snippets should help you dealing with your current situation.
For this sample I use the following documentation:
Data Manipulation Language
Dealing with outputs
Information Schema Tables
Execute Immediate
For...In
Loops
I have a Snowflake stored procedure and I want to use "insert into" without hard coding column names.
INSERT INTO MEMBERS_TARGET (ID, NAME)
SELECT ID, NAME
FROM MEMBERS_STREAM;
This is what I have and column names are hardcoded. The query should copy data from MEMBERS_STREAM to MEMBERS_TARGET. The stream has more columns such as
METADATA$ACTION | METADATA$ISUPDATE | METADATA$ROW_ID
which I am not intending to copy.
I don't know of a way to not copy the METADATA columns if not hardcoding. However if you don't want the data maybe the easiest thing to do is to add them to your target, INSERT using a SELECT * and later in the sp set them to NULL.
Alternatively, earlier in your sp, run an ALTER TABLE ADD COLUMN to add the columns, INSERT using SELECT * and then after that run an ALTER TABLE DROP COLUMN to remove the columns? That way your table structure stays the same, albeit briefly it will have some extra columns.
A SELECT * is not usually recommended but it's the easiest alternative I can think of
I've got multiple master tables in the same format with the same variables. I now want to left join another variable but I can't combine the master tables due to limited storage on my computer. Is there a way that I can left join a variable onto multiple master tables within one PROC SQL? Maybe with the help of a macro?
The LEFT JOIN code looks like this for one join but I'm looking for an alternative than to copy and paste this 5 times:
PROC SQL;
CREATE TABLE New AS
SELECT a.*, b.Value
FROM Old a LEFT JOIN Additional b
ON a.ID = b.ID;
QUIT;
You can't do it in one create table statement, as it only creates one table at a time. But you can do a few things, depending on what your actual limiting factor is (you mention a few).
If you simply want to avoid writing the same code five times, but otherwise don't care how it executes, then just write the code in a macro, as you reference.
%macro update_table(old=, new=);
PROC SQL;
CREATE TABLE &new. AS
SELECT a.*, b.Value
FROM &old. a LEFT JOIN Additional b
ON a.ID = b.ID;
QUIT;
%mend update_table;
%update_table(old=old1, new=new1)
%update_table(old=old2, new=new2)
%update_table(old=old3, new=new3)
Of course, if the names of the five tables are in a pattern, you can perhaps automate this further based on that pattern, but you don't give sufficient information to figure that out.
If you on the other hand need to do this more efficiently in terms of processing than running the SQL query five times, it can be done a number of ways, depending on the specifics of your additional table and your specific limitations. It looks to me that you have a good use case for a format lookup here, for example; see for example Jenine Eason's paper, Proc Format, a Speedy Alternative to Sort/Merge. If you're just merging on the ID, this is very easy.
data for_format;
set additional;
start = ID;
label = value;
fmtname='AdditionalF'; *or '$AdditionalF' if ID is character-valued;
output;
if _n_=1 then do; *creating an "other" option so it returns missing if not found;
hlo='o';
label = ' ';
output;
end;
run;
And then you just have five data steps with a PUT statement adding the value, or even you could simply format the ID variable with that format and it would have that value whenever you did most PROCs (if this is something like a classifier that you don't truly need "in" the data).
You can do this in a single pass through the data in a Data Step using a hash table to lookup values.
data new1 new2 new3;
set old1(in=a) old2(in=b) old3(in=c);
format value best.;
if _n_=1 then do;
%create_hash(lk,id,value,"Additional");
end;
value = .;
rc = lk.find();
drop rc;
if a then
output new1;
else if b then
output new2;
else if c then
output new3;
run;
%create_hash() macro available here.
You could, alternatively, use Joe's format with the same Data Step syntax.
I have 14 fields which are similar and I search the string 'A' on each of them. I would like after that order by "position" field
-- some set in order to remove a lot of useless text
def col='col01'
select '&col' "Fieldname",
&col "value",
position
from oneTable
where &col like '%A%'
/
-- then for the second field, I only have to type two lines
def col='col02'
/
...
def col='col14'
/
Write all the fields which contains 'A'. The problem is that those field are not ordered by position.
If I use UNION between table, I cannot take advantage of the substitution variables (&col), and I have to write a bash in unix in order to make the replacement back into ksh. The problem is of course that database code have to be hard-coded in this script (connection is not easy stuff).
If I use a REFCURSOR with OPEN, I cannot group the results sets together. I have only one request and cannot make an UNION of then. (print refcursor1 union refcursor2; print refcursor1+refcursor2 raise an exception, select * from refcursor1 union select * from refcursor2, does not work also).
How can concatenate results into one big "REFCURSOR"? Or use a union between two distinct run ('/') of my request, something like holding the request while typing new definition of variables?
Thank you for any advice.
Does this answer your question ?
CREATE TABLE #containingAValueTable
(
FieldName VARCHAR(10),
FieldValue VARCHAR(1000),
position int
)
def col='col01'
INSERT INTO #containingAValueTable
(
FieldName , FieldValue, position
)
SELECT '&col' "Fieldname",
&col "value",
position
FROM yourTable
WHERE &col LIKE '%A%'
/
-- then for the second field, I only have to type two lines
def col='col02'
INSERT INTO...
/
def col='col14'
/
select * from #containingAValueTable order by postion
DROP #containingAValueTable
But I'm not totally sure about your use of the 'substitution variable' called "col" (and i only have SQL Server to test my request so I used explicit field names)
edit : Sorry for the '#' charcater, we use it so often in SQL Server for temporaries, I didn't even know it was SQL Server specific (moreover I think it's mandatory in sql server for creating temporary table). Whatever, I'm happy I could be useful to you.
I have two tables coming which has data from two different systems. I need to reconcile the data in these two tables
The column mapping needs to be made configurable.
E.g.:
Table A Table B
Col1A, Col2A Col1B, Col2B
MappingTable
Col1A = Col1B
Col2A= Col2B
So I would need to have two result sets like this based on the mappings in the table.This needs to be decided dynamically. i.e. Select _____ from A. The _____ needs to be filled dynamically.
Select Col1A, Col2A from A
Select Col2B, Col1B from B
Is this possible in MySQL?
Use a UNION clause if the column sets are similar (if they're not you won't be able to combine their results in a meaningful way, anyway).
select col1a, col2a from A
union
select col1b, col2b from b