I have 2 databases in the same server and I need to compare the registers on each one, since one of the databases is not importing all the information
I was trying to do a ROW count but it's not working
Currently I am doing packages of 100,000 rows approximate, and lookup at them in Excel.
Let's say I want a query that does a count for each ID in TABLE A and then compares the count result VS TABLE B count for each ID, since they are the same ID the count should be the same, and I want that brings me the ID on which there where any mismatch between counts.
--this table will contain the count of occurences of each ID in tableA
declare #TableA_Results table(
ID bigint,
Total bigint
)
insert into #TableA_Results
select ID,count(*) from database1.TableA
group by ID
--this table will contain the count of occurences of each ID in tableB
declare #TableB_Results table(
ID bigint,
Total bigint
);
insert into #TableB_Results
select ID,count(*) from database2.TableB
group by ID
--this table will contain the IDs that doesn't have the same amount in both tables
declare #Discordances table(
ID bigint,
TotalA bigint,
TotalB bigint
)
insert into #Discordances
select TA.ID,TA.Total,TB.Total
from #TableA_Results TA
inner join #TableB_Results TB on TA.ID=TB.ID and TA.Total!=TB.Total
--the final output
select * from #Discordances
The question is vague, but maybe this SQL Code might help nudge you in the right direction.
It grabs the IDs and Counts of each ID from database one, the IDs and counts of IDs from database two, and compares them, listing out all the rows where the counts are DIFFERENT.
WITH DB1Counts AS (
SELECT ID, COUNT(ID) AS CountOfIDs
FROM DatabaseOne.dbo.TableOne
GROUP BY ID
), DB2Counts AS (
SELECT ID, COUNT(ID) AS CountOfIDs
FROM DatabaseTwo.dbo.TableTwo
GROUP BY ID
)
SELECT a.ID, a.CountOfIDs AS DBOneCount, b.CountOfIDs AS DBTwoCount
FROM DB1Counts a
INNER JOIN DB2Counts b ON a.ID = b.ID
WHERE a.CountOfIDs <> b.CountOfIDs
This SQL selects from the specific IDs using the "Database.Schema.Table" notation. So replace "DatabaseOne" and "DatabaseTwo" with the names of your two databases. And of course replace TableOne and TableTwo with the names of your tables (I'm assuming they're the same). This sets up two selects, one for each database, that groups by ID to get the count of each ID. It then joins these two selects on ID, and returns all rows where the counts are different.
You could full outer join two aggregate queries and pull out ids that are either missing in one table, or for which the record count is different:
select coalesce(ta.id, tb.id), ta.cnt, tb.cnt
from
(select id, count(*) cnt from tableA) ta
full outer join (select id, count(*) cnt from tableB) tb
on ta.id = tb.id
where
coalesce(ta.cnt, -1) <> coalesce(tb.cnt, -1)
You seem to want aggregation and a full join:
select coalesce(a.id, b.id) as id, a.cnt, b.cnt
from (select id, count(*) as cnt
from a
group by id
) a full join
(select id, count(*) as cnt
from b
group by id
) b
on a.id = b.id
where coalesce(a.cnt, 0) <> coalesce(b.cnt, 0);
Related
I have two tables, table A and table B. There are multiple entries in table B for each entry in table A when joining them together, but I only want to match the 3rd value from table B, which is neither the maximum nor the minimum of the values. The values can be ordered, and it will always be the 3rd value after ordering. Is there a way to do this? Thank you!
WITH
ranked_b AS
(
SELECT
*,
ROW_NUMBER() OVER (PARTITION BY key ORDER BY val) AS key_rank
FROM
table_b
)
SELECT
*
FROM
table_a
INNER JOIN
ranked_b
ON ranked_b.key = table_a.key
AND ranked_b.key_rank = 3
Consider below approach
select key,
array_agg(value order by value limit 3)[safe_ordinal(3)] as value
from tableA
left join tableB
on key = foreignkey
group by key
You can use a correlated subquery:
select a.*,
(select b.value
from b
where b.key = a.key
limit 1 offset 2
)
from a;
I'm trying to select * from two tables (a and b) using a join (column a.id and b.id), given that the count of a column (b.owner) in b is lower than 3, i.e. the occurence of a person's name can be max 2.
I've tried:
SELECT a.*, COUNT(b.owner) AS b_count
FROM a LEFT JOIN b on a.id = b.id
GROUP BY b.owner HAVING COUNT(b_count) <3
As im pretty new to SQL, im pretty stuck here. How can i resolve this issue? The result should be all columns for owners who do not appear more than twice in the data.
The query you are trying to run is not working due to the columns missing in the GROUP BY clause.
As you are outputting all columns from table a (with SELECT a.*), you need to include all those columns in the GROUP BY statement, so that the database understand the group of fields to group by and perform the aggregation required (in your case COUNT(b.owner)).
Example
Considering that your table a has 3 columns below:
CREATE TABLE persons (
id INTEGER,
name VARCHAR(50),
birthday DATE,
PRIMARY KEY (id)
);
.. and your table b the following and referencing the first table as below:
CREATE TABLE sales (
id INTEGER,
person_id INTEGER,
sale_value DECIMAL,
PRIMARY KEY (id),
FOREIGN KEY (person_id) REFERENCES persons(id)
);
.. you should query it aggregating the COUNT() by those 3 columns:
SELECT a.id, a.name, a.birthday, COUNT(b.person_id) AS b_count
FROM persons a
LEFT JOIN sales b ON a.id = b.person_id
GROUP BY a.id, a.name, a.birthday
HAVING COUNT(b.person_id) < 3
Alternative
In case the total of records on the 2nd table is not important to you, you could use a different "strategy" here to avoid performing the JOIN between the tables (useful when joining two huge tables) and rewriting all the columns from a on the SELECT+GROUP BY.
By identifying the records that has less than the 3 occurrences firstly:
SELECT b.person_id
FROM sales b
GROUP BY b.person_id
HAVING COUNT(b.id) < 3;
.. and using it in the WHERE clause to retrieve all the columns from the 1st table only for the ids that resulted from the previous query:
SELECT a.*
FROM persons a
WHERE a.id IN (....other query here....);
.. the execution happens in a more chronological and, perhaps, easier way to visualize while getting more familiar with SQL:
SELECT a.*
FROM persons a
WHERE a.id IN (SELECT b.person_id
FROM sales b
GROUP BY b.person_id
HAVING COUNT(b.id) < 3);
DB Fiddle here
In Standard SQL, you can use:
SELECT a.*, COUNT(b.owner) AS b_count
FROM a LEFT JOIN
b
ON a.id = b.id
GROUP BY a.id
HAVING COUNT(b.owner) < 3;
This may not work in all databases (and it assumes that a.id is unique/primary key). An alternative would be to use a correlated subquery:
SELECT a.*
FROM (SELECT a.*,
(SELECT COUNT(*)
FROM b
WHERE a.id = b.id
) as b_count
FROM a
) a
WHERE b_count < 3;
I have below hive tables
Table_1
ID
1
1
2
Table_2
ID
1
2
2
I am comparing two tables based on count of ID in both tables, I need the output like below
ID
1 - 2records in table 1 and 1 record in Table 2
2 - one record in Table 1 and 2 records in table 2
Table_1 is parent table
i am using below query
select count(*),ID from Table_1 group by ID;
select count(*),ID from Table_2 group by ID;
Just do a full outer join on your queries with the on condition as X.id = Y.id, and then select * from the resultant table checking for nulls on either side.
Select id, concat(cnt1, " entries in table 1, ",cnt2, "entries in table 2") from (select * from (select count(*) as cnt1, id from table1 group by id) X full outer join (select count(*) as cnt2, id from table2 group by id)
on X.id=Y.id
)
Try This. You may use a case statement to check if it should be record / records etc.
SELECT m.id,
CONCAT (COALESCE(a.ct, 0), ' record in table 1, ', COALESCE(b.ct, 0),
' record in table 2')
FROM (SELECT id
FROM table_1
UNION
SELECT id
FROM table_2) m
LEFT JOIN (SELECT Count(*) AS ct,
id
FROM table_1
GROUP BY id) a
ON m.id = a.id
LEFT JOIN (SELECT Count(*) AS ct,
id
FROM table_2
GROUP BY id) b
ON m.id = b.id;
You could use this Python program to do a full comparison of 2 Hive tables:
https://github.com/bolcom/hive_compared_bq
If you want a quick comparison just based on counts, then pass the "--just-count" option (you can also specify the group by column with "--group-by-column").
The script also allows you to visually see all the differences on all rows and all columns if you want a complete validation.
I have 3 tables. All of them have a column - id. I want to find if there is any value that is common across the tables. Assuming that the tables are named a.b and c, if id value 3 is present is a and b, there is a problem. The query can/should exit at the first such occurrence. There is no need to probe further. What I have now is something like
( select id from a intersect select id from b )
union
( select id from b intersect select id from c )
union
( select id from a intersect select id from c )
Obviously, this is not very efficient. Database is PostgreSQL, version 9.0
id is not unique in the individual tables. It is OK to have duplicates in the same table. But if a value is present in just 2 of the 3 tables, that also needs to be flagged and there is no need to check for existence in he third table, or check if there are more such values. One value, present in more than one table, and I can stop.
Although id is not unique within any given table, it should be unique across the tables; a union of distinct id should be unique, so:
select id from (
select distinct id from a
union all
select distinct id from b
union all
select distinct id from c) x
group by id
having count(*) > 1
Note the use of union all, which preserves duplicates (plain union removes duplicates).
I would suggest a simple join:
select a.id
from a join
b
on a.id = b.id join
c
on a.id = c.id
limit 1;
If you have a query that uses union or group by (or order by, but that is not relevant here), then you need to process all the data before returning a single row. A join can start returning rows as soon as the first values are found.
An alternative, but similar method is:
select a.id
from a
where exists (select 1 from b where a.id = b.id) and
exists (select 1 from c where a.id = c.id);
If a is the smallest table and id is indexes in b and c, then this could be quite fast.
Try this
select id from
(
select distinct id, 1 as t from a
union all
select distinct id, 2 as t from b
union all
select distinct id, 3 as t from c
) as t
group by id having count(t)=3
It is OK to have duplicates in the same table.
The query can/should exit at the first such occurrence.
SELECT 'OMG!' AS danger_bill_robinson
WHERE EXISTS (SELECT 1
FROM a,b,c -- maybe there is a place for old-style joins ...
WHERE a.id = b.id
OR a.id = c.id
OR c.id = b.id
);
Update: it appears the optimiser does not like carthesian joins with 3 OR conditions. The below query is a bit faster:
SELECT 'WTF!' AS danger_bill_robinson
WHERE exists (select 1 from a JOIN b USING (id))
OR exists (select 1 from a JOIN c USING (id))
OR exists (select 1 from c JOIN b USING (id))
;
Given
Table A
Id INTEGER
Name VARCHAR(50)
Table B
Id INTEGER
FkId INTEGER ; Foreign key to Table A
I wish to count the occurrances of each FkId value:
SELECT FkId, COUNT(FkId)
FROM B
GROUP BY FkId
Now I simply want to also output the Name from Table A.
This will not work:
SELECT FkId, COUNT(FkId), a.Name
FROM B b
INNER JOIN A a ON a.Id=b.FkId
GROUP BY FkId
because a.Name is not contained in the GROUP BY clause (produces is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause error).
The point is to move from output like this
FkId Count
1 42
2 25
to output like this
FkId Count Name
1 42 Ronald
2 22 John
There are quite a few matches on SO for that error message, but some e.g. https://stackoverflow.com/a/6456944/141172 have comments like "will generate 3 scans on the table, rather than 1, so won't scale".
How can I efficiently include a field from the joined Table B (which has a 1:1 relationship to FkId) in the query output?
You can try something like this:
;WITH GroupedData AS
(
SELECT FkId, COUNT(FkId) As FkCount
FROM B
GROUP BY FkId
)
SELECT gd.*, a.Name
FROM GroupedData gd
INNER JOIN dbo.A ON gd.FkId = A.FkId
Create a CTE (Common Table Expression) to handle the grouping/counting on your Table B, and then join that result (one row per FkId) to Table A and grab some more columns from Table A into your final result set.
Did you try adding the field to the group by?
SELECT FkId, COUNT(FkId), a.Name
FROM B b
INNER JOIN A a ON a.Id=b.FkId
GROUP BY FkId,a.Name
select t3.Name, t3.FkId, t3.countedFkId from (a t1
join (select t2.FkId, count(FkId) as countedFkId from b t2 group by t2.FkId)
on t1.Id = t2.FkId) t3;