I have two separate SELECT statements:
SELECT VCe.VId FROM `VCe` WHERE `YId` = 9007 AND `MaId` =76 AND `MoId` = 2851
SELECT r_pts.p_id FROM r_pts WHERE r_pts.v_id IN (57202, 57203, 69597, 82261, 82260, 69596, 69595, 82259)
When they are run separately they both complete in under .05sec however when I nest the first one within the second, it dramatically increases to 3.3sec.
I would like to do a join so that I can get the output from the second SELECT using the first select as the result set for the IN() but I cannot figure out how to include WHERE conditions in a JOIN.
Edit: Also what is the correct syntax to do a join as I am requesting?
Thanks for your help, its appreciated!
Equivalent to MattMcKnight's query whilst illustrating "how to include WHERE conditions in a JOIN":
SELECT r.p_id
FROM r_pts r
INNER JOIN VCe v
ON v.VId = r.v_id
AND
v.YId = 9007
AND
v.MaId = 76
AND
v.MoId = 2851
SELECT r_pts.p_id FROM r_pts, 'VCe' WHERE r_pts.v_id = VCe.VId AND VCe.YId = 9007 AND VCe.MaId =76 AND VCe.MoId = 2851
The basic goal of a join is to describe how the two tables relate. I inferred from your example that the v_id column in the r_pts table was a foreign key pointing to the VId primary key in the VCe table. When you add a term in the query (such as "r_pts.v_id = VCe.VId") that has a field from each table you wish to join, that tells the database how to match up the rows between the tables to make "virtual rows" that contain the columns from both tables. Your other query terms limit which rows are included in the result set.
Related
I have 3 tables:
pd_tprofessional, pd_tpreference and pd_tprofessional_preference.
pd_tprofessional and pd_tpreference have unique id (fkprofessional and fkpreference, respectively).
pd_tprofessional_preference has 3 columns: fkpreference, patientpreference_selected, fkprofessional
What I am trying to do is write a query that will get all the all pd_tpreference and return patientpreference_selected as 1 or 0 based on if fkprofessional is 13 and pd_tprofessional_preference with that fkprofessional exists.
This is what I got so far:
SELECT patientpreference_selected, fkprofessional, pkpreference, preference_name
FROM pd_tprofessional_preference
RIGHT OUTER JOIN pd_tpreference
ON pd_tpreference.pkpreference = pd_tprofessional_preference.fkpreference
This query gives me all the pd_tpreference by right outer joining them with pd_tprofessional_preference, now I am stuck on returning patientpreference_selected as 1 or 0 based if that record exists in pd_tprofessional_preference when the fkprofessional is 13 with the fkpreference. I really hope this makes sense.
Conventional and easily readable way is using Left Join. You can do a left-join from the pd_tpreference table to the pd_tprofessional_preference table.
In the join ON condition, specify the condition that fkprofessional = 13.
You can use Coalesce() function to handle the case when there is no match found in the pd_tprofessional_preference table.
In multi-table queries, it is advisable to use Aliasing for code clarity and avoiding ambiguous behaviour.
Try the following:
SELECT
pref_t.fkpreference,
pref_t.preference_name,
map_t.fkprofessional,
COALESCE(map_t.patientpreference_selected, 0) AS patientpreference_selected
FROM pd_tpreference AS pref_t
LEFT JOIN pd_tprofessional_preference AS map_t
ON map_t.fkpreference = pref_t.fkpreference AND
map_t.fkprofessional = 13
I'm trying to write a MYSQL Query that updates a cell in table1 with information gathered from 2 other tables;
The gathering of data from the other 2 tables goes without much issues (it is slow, but that's because one of the 2 tables has 4601537 records in it.. (because all the rows for one report are split in a separate record, meaning that 1 report has more than 200 records)).
The Query that I use to Join the two tables together is:
# First Table, containing Report_ID's: RE
# Table that has to be updated: REGI
# Join Table: JT
SELECT JT.report_id as ReportID, REGI.Serienummer as SerialNo FROM Blancco_Registration.TrialTable as REGI
JOIN (SELECT RE.Value_string, RE.report_id
FROM Blancco_new.mc_report_Entry as RE
WHERE RE.path_id=92) AS JT ON JT.Value_string = REGI.Serienummer
WHERE REGI.HardwareType="PC" AND REGI.BlanccoReport=0 LIMIT 100
This returns 100 records (I limit it because the database is in use during work hours and I don't want to steal all resources).
However, I want to use these results in a Query that updates the REGI table (which it uses to select the 100 records in the first place).
However, I get the error that I cannot select from the table itself while updateing it (logically). So I tried selecting the select statement above into a temp table and than Update it; however, then I get the issue that I get to much results (logically! I only need 1 result and get 100) however, I'm getting stuck in my own thougts.. I ultimately need to fill the ReportID into each record of REGI.
I know it should be possible, but I'm no expert in MySQL.. is there anybody that can point me into the right direction?
Ps. fixing the table containing 400k records is not an option, it's a program from an external developer and I can only read that database.
The errors I'm talking about are as follows:
Error Code: 1093. You can't specify target table 'TrialTable' for update in FROM clause
When I use:
UPDATE TrialTable SET TrialTable.BlanccoReport =
(SELECT JT.report_id as ReportID, REGI.Serienummer as SerialNo FROM Blancco_Registration.TrialTable as REGI
JOIN (SELECT RE.Value_string, RE.report_id
FROM Blancco_new.mc_report_Entry as RE
WHERE RE.path_id=92) AS JT ON JT.Value_string = REGI.Serienummer
WHERE REGI.HardwareType="PC" AND REGI.BlanccoReport=0 LIMIT 100)
WHERE TrialTable.HardwareType="PC" AND TrialTable.BlanccoReport=0)
Then I tried:
UPDATE TrialTable SET TrialTable.BlanccoReport = (SELECT ReportID FROM (<<and the rest of the SQL>>> ) as x WHERE X.SerialNo = TrialTable.Serienummer)
but that gave me the following error:
Error Code: 1242. Subquery returns more than 1 row
Haveing the Query above with a LIMIT 1, gives everything the same result
Firstly, your query seems to be functionally identical to the following:
SELECT RE.report_id ReportID
, REGI.Serienummer SerialNo
FROM Blancco_Registration.TrialTable REGI
JOIN Blancco_new.mc_report_Entry RE
ON RE.Value_string = REGI.Serinummer
WHERE REGI.HardwareType = "PC"
AND REGI.BlanccoReport=0
AND RE.path_id=92
LIMIT 100
So, why not use that?
EDIT:
I still don't get it. I can't see what part of the problem the following fails to solve...
UPDATE TrialTable REGI
JOIN Blancco_new.mc_report_Entry RE
ON RE.Value_string = REGI.Serinummer
SET TrialTable.BlanccoReport = RE.report_id
WHERE REGI.HardwareType = "PC"
AND REGI.BlanccoReport=0
AND RE.path_id=92;
(This is not an answer, but maybe a pointer towards a few points that need further attention)
Your JT sub query looks suspicious to me:
(SELECT RE.Value_string, RE.report_id
FROM Blancco_new.mc_report_Entry as RE
WHERE RE.path_id=92
GROUP BY RE.report_id)
You use group by but don't actually use any aggregate functions. The column RE.Value_string should strictly be something like MAX(RE.Value_string) instead.
I know this has been asked plenty times before, but I cant find an answer that is close to mine.
I have the following query:
SELECT c.cases_ID, c.cases_status, c.cases_title, ci.custinfo_FName, ci.custinfo_LName, c.cases_timestamp, o.organisation_name
FROM db_cases c, db_custinfo ci, db_organisation o
WHERE c.userInfo_ID = ci.userinfo_ID AND c.cases_status = '2'
AND organisation_name = (
SELECT organisation_name
FROM db_sites s, db_cases c
WHERE organisation_ID = '111'
)
AND s.sites_site_ID = c.sites_site_ID)
What I am trying to do is is get the cases, where the sites_site_ID which is defined in the cases, also appears in the db_sites sites table alongside its organisation_ID which I want to filter by as defined by "organisation_ID = '111'" but I am getting the response from MySQL as stated in the question.
I hope this makes sense, and I would appreciate any help on this one.
Thanks.
As the error states your subquery returns more then one row which it cannot do in this situation. If this is not expect results you really should investigate why this occurs. But if you know this will happen and want only the first result use LIMIT 1 to limit the results to one row.
SELECT organisation_name
FROM db_sites s, db_cases c
WHERE organisation_ID = '111'
LIMIT 1
Well the problem is, obviously, that your subquery returns more than one row which is invalid when using it as a scalar subquery such as with the = operator in the WHERE clause.
Instead you could do an inner join on the subquery which would filter your results to only rows that matched the ON clause. This will get you all rows that match, even if there is more than one returned in the subquery.
UPDATE:
You're likely getting more than one row from your subquery because you're doing a cross join on the db_sites and db_cases table. You're using the old-style join syntax and then not qualifying any predicate to join the tables on in the WHERE clause. Using this old style of joining tables is not recommended for this very reason. It would be better if you explicitly stated what kind of join it was and how the tables should be joined.
Good pages on joins:
http://dev.mysql.com/doc/refman/5.0/en/join.html (for the right syntax)
http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html (for the differences between the types of joins)
I was battling this for an hour, and overcomplicated it completely. Sometimes a quick break and writing it out on an online forum can solve it for you ;)
Here is the query as it should be.
SELECT c.cases_ID, c.cases_status, c.cases_title, ci.custinfo_FName, ci.custinfo_LName, c.cases_timestamp, c.sites_site_ID
FROM db_cases c, db_custinfo ci, db_sites s
WHERE c.userInfo_ID = ci.userinfo_ID AND c.cases_status = '2' AND (s.organisation_ID = '111' AND s.sites_site_ID = c.sites_site_ID)
Let me re-write what you have post:
SELECT
c.cases_ID, c.cases_status, c.cases_title, ci.custinfo_FName, ci.custinfo_LName,
c.cases_timestamp, c.sites_site_ID
FROM
db_cases c
JOIN
db_custinfo ci ON c.userInfo_ID = ci.userinfo_ID and c.cases_status = '2'
JOIN
db_sites s ON s.sites_site_ID = c.sites_site_ID and s.organization_ID = 111
Query 1:
select name,trans from sids s where apt='KAUS';
Query 2:
SELECT id,transition_id from std_sid_leg where data_supplier='E' and airport='KAUS';
Values of name is same that of id and trans with transition_id.Result set 1 is subset of result set 2.Both the tables have common columns as apt=airport
If query alone couldnt work please provide any script.
I need to compare the outputs of these 2 queries and print the data differences.
Thank you.
You're looking for a combined left+right join.
This is called an full outer join (as opposed to a left/right outer join).
By selecting only the rows where join columns are null you'll get the mismatches; this is called an anti-join.
The full outer-anti-join looks like this:
select s.*, ssl.*
from sids s
outer join std_sid_leg ssl on (s.name = ssl.id and s.trans = ssl.transition_id)
where (s.name is null and s.trans is null)
or (ssl.id is null and ssl.transition_id is null)
I realized that i was using a varchar attribute as a index/key in a query, and that is killing my query performance. I am trying to look in my precienct table and get the integer ID, and then update my record in the household table with the new int FK, placed in a new column. this is the sql i have written thus far. but i am getting a
Error 1093 You can't specify target table 'voterfile_household' for update in FROM clause, and i am not sure how to fix it.
UPDATE voterfile_household
SET
PrecID = (SELECT voterfile_precienct.ID
FROM voterfile_precienct INNER JOIN voterfile_household
WHERE voterfile_precienct.PREC_ID = voterfile_household.Precnum);
Try:
update voterfile_household h, voterfile_precienct p
set h.PrecID = p.ID
where p.PREC_ID = h.Precnum
Take a look at update reference here.
Similarly, you can use inner join syntax as well.
update voterfile_household h inner join voterfile_precienct p on (h.Precnum = p.PREC_id)
set h.PrecID = p.ID
What if the subquery returns more than one result? That's why it doesn't work.
On SQL Server you can get this type of thing to work if the subquery does "SELECT TOP 1 ...", not sure if mysql will also accept it if you add a "limit 1" to the subquery.
I also think this is pretty much a duplicate of this question ("Can I have an inner SELECT inside of an SQL UPDATE?") from earlier today.
Firstly, your index on a varchar isn't always a bad thing, if it is not a key you can shrink how much of the field you index to only index say the first 10 chars or so.
Secondly, it won't let you do this as if it is a set that is returned it could break.