python (12.9k questions)

javascript (9.2k questions)

reactjs (4.7k questions)

java (4.2k questions)

java (4.2k questions)

c# (3.5k questions)

c# (3.5k questions)

html (3.3k questions)

Questions - subquery

MariaDB: Using PK for inner query result

I have three tables (MariaDB 10.6.5): person, private_person and corporate_person. In the person are Ids stored, in the other tables are names stored, both connected to the person per FK: CREATE TABLE...
test-img

Dave_B.

mysql

indexing

mariadb

subquery

query-optimization

Votes: 0

Answers: 2

Latest Answer

It's the OR operations that doom your query. WHERE `p0`.`FirstName` = 'Test' OR p0.LastName = 'Test' OR `c0`.`Name` = 'Test'; This is a common problem with query optimization, given that MySQL uses...
test-img

Bill Karwin

SqLite query with multiple aggregation functions are slow - need help to optimize the query

I need help optimizing this query for sqlite (query run from php): select max(aid) as aid, max(mid) as mid ,max(tid) as tid, max(m.id) as m_mid, max(t.id) as m_tid, max(a.id) as m_aid from dv...
test-img

DDS

php

sql

sqlite

subquery

max

Votes: 0

Answers: 1

Latest Answer

Your FROM clause: from dview, T_DATA t, M_DATA m, A_DATA a creates a cartesian product of all the combinations of rows of the 4 datasets and it produces huge dataset on which the aggregation is final...
test-img

forpas

How can I use an operator In the where clause to compare the results returned from a subquery?

I would like to use a greater than operator to find the students in the outer query that have a greater salary than the students in the subquery. I tried using a > the operator in the where clause,...
test-img

zahid habib

mysql

subquery

where-clause

operator-keyword

comparison-operators

mysql

subquery

where-clause

operator-keyword

comparison-operators

Votes: 0

Answers: 1

Latest Answer

You could try a workaround. You could add an outer query with the max value of the subquery records and compare with that single value. Note that this solution only include all the student on the ou...
test-img

Ergest Basha

Getting different results from Subquery and JOIN which seem to be the same

I'm doing a challenge problem on DataCamp. It uses two tables, "economies" which contains economic information by country code, and "countries" which contains general country infor...
test-img

Christopher V Elwood

sql

join

subquery

left-join

Votes: 0

Answers: 1

Latest Answer

In the first query you destroy the effect of the left join by putting conditions on the fields of the joined table. For example, c.gov_form <> 'Constitutional Monarchy' will be false when there ...
test-img

trincot

Posts

Questions

Blogs

Jobs