Lets say we have the usual Oracle Employees and Departments tables.
I also have some Oracle Object types:
TEmployee: an object type that has the same members as fields in Table Employees.
TEmployeeList: an object table of TEmployee.
TDepartment: an object type that has the same members as fields in Table Departments.
TDepartment also has a member "employees" of type TEmployeeList.
TDepartmentList: an object table of TDepartment.
Now I want to bulk collect a number of departments with their employees in a single query.
I know how to bulk collect the departments without the employees:
DECLARE
departmentList TDepartmentList;
BEGIN
SELECT TDepartment(dept.id, dept.name)
BULK COLLECT INTO departmentList
FROM departments dept
WHERE <some condition>;
END;
But how can I collect the employees of the selected departments in the same query?
Thus something like
DECLARE
departmentList TDepartmentList;
BEGIN
SELECT TDepartment(dept.id, dept.name,
SELECT TEmployee(emp.id, emp.name)
FROM Employees
WHERE emp.deptId = dept.id
)
BULK COLLECT INTO departmentList
FROM departments dept
WHERE <some condition>;
END;
Ok, I found it:
DECLARE
departmentList TDepartmentList;
BEGIN
SELECT TDepartment(dept.id, dept.name,
CAST(MULTISET(
SELECT TEmployee(emp.id, emp.name)
FROM Employees
WHERE emp.deptId = dept.id
) AS TEmployeeList))
)
BULK COLLECT INTO departmentList
FROM departments dept
WHERE <some condition>;
END;
So the CAST(MULTISET( query ) AS TEmployeeList) is what I added.
Related
i have i would like to create a join over several tables.
table login : I would like to retrieve all the data from login
table logging : calculating the Nb_of_sessions for each db & for each a specific event type by user
table meeting : calculating the Nb_of_meetings for each db & for each user
table live : calculating the Nb_of_live for each db & for each user
I have those queries with the right results :
SELECT db.id,_id as userid,firstname,lastname
FROM "logins"."login",
UNNEST(dbs) AS a1 (db)
SELECT dbid,userid,count(distinct(sessionid)) as no_of_visits,
array_join(array_agg(value.from_url),',') as from_url
FROM "loggings"."logging"
where event='url_event'
group by db.id,userid;
SELECT dbid,userid AS userid,count(*) as nb_interviews,
array_join(array_agg(interviewer),',') as interviewer
FROM "meetings"."meeting"
group by dbid,userid;
SELECT dbid,r1.user._id AS userid,count(_id) as nb_chat
FROM "lives"."live",
UNNEST(users) AS r1 (user)
group by dbid,r1.user._id;
But when i begin to try put it all together, it seems i retrieve bad data (i have only on db retrieved) and it seems not efficient.
select a1.db.id,a._id as userid,a.firstname,a.lastname,count(rl._id) as nb_chat
FROM
"logins"."login" a,
"loggings"."logging" b,
"meetings"."meeting" c,
"lives"."live" d,
UNNEST(dbs) AS a1 (db),
UNNEST(users) AS r1 (user)
where a._id = b.userid AND a._id = c.userid AND a._id = r1.user._id
group by 1,2,3,4
Do you have an idea ?
Regards.
The easiest way is to work with with to structure the subquery and then reference them.
with parameter reference:
You can use WITH to flatten nested queries, or to simplify subqueries.
The WITH clause precedes the SELECT list in a query and defines one or
more subqueries for use within the SELECT query.
Each subquery defines a temporary table, similar to a view definition,
which you can reference in the FROM clause. The tables are used only
when the query runs.
Since you already have working sub queries, the following should work:
with logins as
(
SELECT db.id,_id as userid,firstname,lastname
FROM "logins"."login",
UNNEST(dbs) AS a1 (db)
)
,visits as
(
SELECT dbid,userid,count(distinct(sessionid)) as no_of_visits,
array_join(array_agg(value.from_url),',') as from_url
FROM "loggings"."logging"
where event='url_event'
group by db.id,userid
)
,meetings as
(
SELECT dbid,userid AS userid,count(*) as nb_interviews,
array_join(array_agg(interviewer),',') as interviewer
FROM "meetings"."meeting"
group by dbid,userid
)
,chats as
(
SELECT dbid,r1.user._id AS userid,count(_id) as nb_chat
FROM "lives"."live",
UNNEST(users) AS r1 (user)
group by dbid,r1.user._id
)
select *
from logins l
left join visits v
on l.dbid = v.dbid
and l.userid = v.userid
left join meetings m
on l.dbid = m.dbid
and l.userid = m.userid
left join chats c
on l.dbid = c.dbid
and l.userid = c.userid;
I have different databases. I have tables within each database.
I would like to know if I can ask how many databases excluding some such as 'schema' 'mysql' I have once know how to perform a subquery asked by a particular table of all the databases resulting from the first question.
example.
the structure would be
db1 -> user-> id,name,imei,telephone,etc..
db2 -> user-> id,nameuser,imei,telephone,etc..
db3 -> user-> id,nameuser,imei,telephone,etc..
....
db1000 -> user-> id,nameuser,imei,telephone,etc..
the query are how this, but this get error
SELECT CONCAT('SELECT * FROM ' schema_name 'where imei.'schema_name = nameimai)
FROM information_schema.schemata
WHERE schema_name NOT IN ('information_schema','mysql','performance_schema','sys','performance_schema','phpmyadmin');
Results
name db id name imei phone
---------- ---------- ---------- ---------- ----------
db1 1 John 76876876 xxx
db2 2300 John 76876876 xxxx
...
db1000 45 John 76876876 xxx
its possible in one query
thanks..
Here's one way you could do it with a stored procedure.
If I understand correctly, you have multiple databases with identical tables (user) and you want to run a query against all these tables for a specific value.
I've made this fairly general so that you can pass in the table name and also the where clause. Your example seemed to be looking for user records with imei = '76876876', so if we use that example.
USE test;
DELIMITER //
DROP PROCEDURE IF EXISTS multidb_select //
-- escape any quotes in the query string
-- call multidb_select ('usertest','WHERE imei = \'76876876\'')
CREATE PROCEDURE multidb_select(IN tname VARCHAR(64), IN qwhere VARCHAR(1024))
READS SQL DATA
BEGIN
DECLARE vtable_schema VARCHAR(64);
DECLARE vtable_name VARCHAR(64);
DECLARE done BOOLEAN DEFAULT FALSE;
-- exclude views and system tables
DECLARE cur1 CURSOR FOR
SELECT `table_schema`, `table_name`
FROM `information_schema`.`tables`
WHERE `table_name` = tname
AND `table_type` = 'BASE TABLE'
AND `table_schema` NOT IN
('information_schema','mysql','performance_schema',
'sys','performance_schema','phpmyadmin')
ORDER BY `table_schema` ASC;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done := TRUE;
OPEN cur1;
SET #unionall := '';
read_loop: LOOP
FETCH cur1 INTO vtable_schema, vtable_name;
IF done THEN
LEAVE read_loop;
END IF;
-- UNION ALL in case the id is the same
IF CHAR_LENGTH(#unionall) = 0 THEN
SET #unionall =
CONCAT("SELECT \'", vtable_schema , "\' AS 'Db', t.* FROM `",
vtable_schema, "`.`" , vtable_name, "` t ", qwhere);
ELSE
SET #unionall =
CONCAT(#unionall, " UNION ALL SELECT \'", vtable_schema ,
"\' AS 'Db', t.* FROM `", vtable_schema,
"`.`", vtable_name, "` t ", qwhere);
END IF;
END LOOP;
CLOSE cur1;
PREPARE stmt FROM #unionall;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END //
DELIMITER ;
Run it with
call test.multidb_select('user','WHERE imei = \'76876876\'')
Is it possible to use .QueryMultiple (or some other method) in Dapper, and use the results of each former query to be used in the where clause of the next query, without having to do each query individually, get the id, and then .Query again, get the id and so on.
For example,
string sqlString = #"select tableA_id from tableA where tableA_lastname = #lastname;
select tableB_id from tableB WHERE tableB_id = tableA_id";
db.QueryMultiple.(sqlString, new {lastname = "smith"});
Is something like this possible with Dapper or do I need a view or stored procedure to accomplish this? I can use multiple joins for one SQL statement, but in my real query there are 7 joins, and I didn't think I should return 7 objects.
Right now I'm just using object.
You can store every previous query in table parameter and then first perform select from the parameter and query for next, for example:
DECLARE #TableA AS Table(
tableA_id INT
-- ... all other columns you need..
)
INSERT #TableA
SELECT tableA_id
FROM tableA
WHERE tableA_lastname = #lastname
SELECT *
FROM #TableA
SELECT tableB_id
FROM tableB
JOIN tableA ON tableB_id = tableA_id
I am working with an Oracle 11g database, release 11.2.0.3.0 - 64 bit production
I have written the following procedure which uses a cursor to collect batches of benefit_ids (which are simply of type NUMBER) from a table called benefit_info. For each benefit_id within each batch, I need to obtain the associated customers and then perform various calculations etc. So far I have the following:
CREATE OR REPLACE PROCEDURE ben_correct(in_bulk_collect_limit IN PLS_INTEGER DEFAULT 1000)
IS
TYPE ben_identity_rec IS RECORD
(
life_scd_id NUMBER,
benefit_id NUMBER
);
TYPE ben_identity_col IS TABLE OF ben_identity_rec INDEX BY PLS_INTEGER;
life_col ben_identity_col;
ben_id NUMBER;
CURSOR benefit_cur
IS
SELECT benefit_id FROM benefit_info;
TYPE benefit_ids_t IS TABLE OF NUMBER INDEX BY PLS_INTEGER;
benefit_ids benefit_ids_t;
PROCEDURE get_next_set_of_incoming(out_benefit_ids OUT NOCOPY benefit_ids_t)
IS
BEGIN
FETCH benefit_cur
BULK COLLECT INTO out_benefit_ids
LIMIT in_bulk_collect_limit;
END;
BEGIN
OPEN benefit_cur;
LOOP
get_next_set_of_incoming(benefit_ids);
/*
The code below is too slow as each benefit_id is considered
individually. Want to change FOR LOOP into LEFT JOIN of benefit_ids
*/
FOR indx IN 1 .. benefit_ids.count LOOP
ben_id := benefit_ids(indx);
SELECT c.life_scd_id, c.benefit_id
BULK COLLECT INTO life_col
FROM customer c
WHERE c.benefit_id = ben_id;
-- Now do further processing with life_col
END LOOP;
EXIT WHEN benefit_ids.count = 0;
END LOOP;
CLOSE benefit_cur;
END;
/
As indicated in the code above, the FOR indx IN 1 .. LOOP is VERY slow, particularly as there are millions of benefit_ids. However, I am aware I can replace the entire FOR LOOP with something like:
SELECT c.life_scd_id, c.benefit_id
BULK COLLECT INTO life_col
FROM customer c
LEFT JOIN table(benefit_ids) b
WHERE b.benefit_id IS NOT NULL;
However, for that to work I think I need to declare an Object type at the schema level as I think in the SELECT query you can join on pure tables or collections of objects. Therefore, from the procedure I remove
TYPE benefit_ids_t IS TABLE OF NUMBER INDEX BY PLS_INTEGER;
and instead at the schema level I have defined
CREATE OR REPLACE TYPE ben_id FORCE AS object
(
benefit_id number
);
CREATE OR REPLACE TYPE benefit_ids_t FORCE AS TABLE OF ben_id;
My revised code essentially becomes:
CREATE OR REPLACE PROCEDURE ben_correct(in_bulk_collect_limit IN PLS_INTEGER DEFAULT 1000)
IS
sql_str VARCHAR2(1000);
TYPE ben_identity_rec IS RECORD
(
life_scd_id NUMBER,
benefit_id NUMBER
);
TYPE ben_identity_col IS TABLE OF ben_identity_rec INDEX BY PLS_INTEGER;
life_col ben_identity_col;
CURSOR benefit_cur
IS
SELECT benefit_id FROM benefit_info;
--- benefit_ids_t has now been declared at schema level
benefit_ids benefit_ids_t;
PROCEDURE get_next_set_of_incoming(out_benefit_ids OUT NOCOPY benefit_ids_t)
IS
BEGIN
FETCH benefit_cur
BULK COLLECT INTO out_benefit_ids
LIMIT in_bulk_collect_limit;
END;
BEGIN
OPEN benefit_cur;
LOOP
get_next_set_of_incoming(benefit_ids);
sql_str := 'SELECT c.life_scd_id, c.benefit_id
FROM customer c
LEFT JOIN table(benefit_ids) b
WHERE b.benefit_id IS NOT NULL';
EXECUTE IMMEDIATE sql_str BULK COLLECT INTO life_col;
-- Now do further processing with life_col
EXIT WHEN benefit_ids.count = 0;
END LOOP;
CLOSE benefit_cur;
END;
/
However, this generates ORA-24344 and PLS-00386 errors, ie type mismatch found at 'OUT_BENEFIT_IDS' between FETCH cursor and INTO variables.
I sort of understand that it is complaining that benefit_ids_t is now a table of ben_ids, which are in turn objects of type number, which is in't quite the same as a table of numbers.
I've tried various attempts at resolving the issues, but I can't seem to quite get it right. Any help would be gratefully appreciated.
Also, any general comments to improve are welcome.
You don't need your table type to be of an object containing a number field, it can just be a table of numbers:
CREATE OR REPLACE TYPE benefit_ids_t FORCE AS TABLE OF number;
Or you can use a built-in type like sys.odcinumberlist, but having your own type under your control isn't a bad thing.
You don't want to use dynamic SQL though; this:
sql_str := 'SELECT c.life_scd_id, c.benefit_id
FROM customer c
LEFT JOIN table(benefit_ids) b
WHERE b.benefit_id IS NOT NULL';
EXECUTE IMMEDIATE sql_str BULK COLLECT INTO life_col;
won't work because benefit_ids isn't in scope when that dynamic statement is executed. You can just do it statically:
SELECT c.life_scd_id, c.benefit_id
BULK COLLECT INTO life_col
FROM table(benefit_ids) b
JOIN customer c
ON c.benefit_id = b.column_value;
which is closer to what you had in your original code.
Your EXIT is also in the wrong place - it will try to process rows in a loop when it doesn't find any. I wouldn't bother with the separate fetch procedure at all, it's easier to follow with the fetch directly in the loop:
BEGIN
OPEN benefit_cur;
LOOP
FETCH benefit_cur
BULK COLLECT INTO benefit_ids
LIMIT in_bulk_collect_limit;
EXIT WHEN benefit_ids.count = 0;
SELECT c.life_scd_id, c.benefit_id
BULK COLLECT INTO life_col
FROM table(benefit_ids) b
JOIN customer c
ON c.benefit_id = b.column_value;
-- Now do further processing with life_col
END LOOP;
CLOSE benefit_cur;
END;
If you did really want your object type, you could keep that, but you would need to make your cursor return instances of that object, via its default constructor:
CURSOR benefit_cur
IS
SELECT ben_id(benefit_id) FROM benefit_info;
The customer query join would then be:
SELECT c.life_scd_id, c.benefit_id
BULK COLLECT INTO life_col
FROM table(benefit_ids) b
JOIN customer c
ON c.benefit_id = b.benefit_id;
As it's an object type you can refer to it's field name, benefit_id, rather than the generic column_value from the scalar type table.
Forgive my ignorance with Linq to SQL but...
How do you query mulitple tables in one fell swoop?
Example:
I want to query, say 4 tables for a title that includes the following word "penguin". Funnily enough each table also has a field called TITLE.
Tables are like so:
I want to query each table (column: TITLE) for the word "penguin". Each table is referenced (via foreign key) to a parent table that is simply called Reference, and is linked on a column called REF_ID. So ideally the result should come back with a list of REF_ID's where the query criteria was matched.
If you can help you will be richly rewarded....... (with a green tick ;)
The code I have works for just one table - but not for two:
var refs = db.REFERENCEs
.Include(r => r.BOOK).Where(r => r.BOOK.TITLE.Contains(titleString)).Include(r => r.JOURNAL.AUTHORs)
.Include(r => r.JOURNAL).Where(r => r.JOURNAL.TITLE.Contains(titleString));
I had a similar scenario a while back and ended up creating a view that unioned my tables and then mapped that view to a LINQ-to-SQL entity.
Something like this:
create view dbo.References as
select ref_id, title, 'Book' as source from dbo.Book
union all
select ref_id, title, 'Journal' from dbo.Journal
union all
select ref_id, title, 'Magazine' from dbo.Magazine
union all
select ref_id, title, 'Report' from dbo.Report
The mapping would look like this (using attributes):
[Table(Name="References")]
public class Reference {
[Column(Name="Ref_Id", IsPrimaryKey=true)]
public int Id {get;set;}
[Column]
public string Title {get;set;}
[Column]
public string Source {get;set;}
}
Then a query might look like this:
var query = db.GetTable<Reference>().Where(r => r.Title.Contains(titleString));