I'm working on my website and I'm stuck on writing MySQL query which uses "LEFT JOIN" syntax. A simple example of my query is shown bellow:
SELECT p.surname, f.f_path as players_image
FROM player p LEFT JOIN file f ON p.id_image = f.id_file
The problem is that I'm actually using 8 different tables to get necessary data and I'm joining them after WHERE clause(I found it more easier to do that way):
SELECT p.surname, f.f_path as players_image
FROM player, file
WHERE p.id_image = f.id_file
Can I somehow modify the second queries WHERE clause to get the same result as the first query returns?
I know that Oracle DB uses syntax like WHERE p.id_image(+) = f.id_file to manage that. It tried that on MySQL data base but it gave me an error.
The original SQL query(table names are different):
SELECT sp.id_speletajs, sp.vards, sp.uzvards, ss.numurs, f.f_path as attels, k.id_komanda, p.nosaukums as pozicija
FROM speletajs sp, fails f, speletaja_statistika ss, cempionata_komanda ck, komanda k, cempionats c, sezona s, pozicija p
WHERE
sp.id_attels = f.id_fails
and sp.id_speletajs = ss.id_speletajs
and ss.id_cempionata_komanda = ck.id_cempionata_komanda
and ss.id_pozicija = p.id_pozicija
and ck.id_komanda = k.id_komanda
and ck.id_cempionats = c.id_cempionats
and c.id_sezona = s.id_sezona
and k.mana_komanda = true
and s.nosaukums = (select max(s1.nosaukums) from sezona s1)
Related
1. Summarise the problem
Our company has been using this system for a long time and people feel huge system slowdown. I can't rewrite code because its super hardcoded and too many files to do so.
Few months ago we saw that one query takes about 170 s to execute.
My workaround was add LIMITS to each query and from 170s it went down to 2-3s. But last week i saw that code now takes about 5-25 sec.
Also this system is on php 5.2. Its basically impossible to upgrade code to work for 5.6
3 people was rewriting this code and after 8 hour we managed to make to login page.
Indexing is limited because most of database info have strings rather than integer.
2. Provide background including what you've already tried
What i tried:
- Adding limits by default 300, also users can change this limit.
- Migrating server to better hardware.
- Giving more RAM (10gb now) and two virtual CPU.
- Migrating from local storage to network (better performance at this moment).
3. Show some code
SELECT pastabos_apskaitininkui,
uzdaviniai.pakr_salis,
uzdaviniai.iskr_salis,
uzdaviniai.id AS uzdavinio_id,
salys.salis AS muitines_salis,
uzdaviniai.pakr_regionas,
uzdaviniai.iskr_regionas,
uzdaviniai.pakr_miestas,
uzdaviniai.iskr_miestas,
uzdavinio_priekaba,
priekabos.tipas AS priekabos_tipas,
uzdaviniai.kas_sukure_skyrius,
uzdaviniai.kam_sukure_skyrius,
uzdaviniai.kas_sukure_vadyb,
uzdaviniai.kam_sukure_vadyb,
uzdav_users.vardas_sutr AS uzdav_user_vardas,
pakrov_salis.sutrumpinimas AS uzdav_pakr_salis,
iskrov_salis.sutrumpinimas AS uzdav_iskr_salis,
uzdaviniai.pasikrovimo_data AS uzd_pasikrovimo_data,
uzdaviniai.pristatymo_data AS uzd_pristatymo_data,
uzdaviniai.pastabos,
suma_vykdytojui_valiuta,
vykdytojui_valiuta,
uzdaviniai.eil_nr,
uzdaviniai.statusas,
uzdaviniai.statusas_baigtas_ranka,
keliones_lapas.reiso_nr,
keliones_lapas.masina,
keliones_lapas.masinos_id,
keliones_lapas.priekabos_nr,
keliones_lapas.priekabos_id,
keliones_lapas.priekabos2_nr,
keliones_lapas.reiso_pavadinimas,
keliones_lapas.vykdytojo_tipas,
keliones_lapas.vykdytojo_imone,
keliones_lapas.atvykimo_data,
keliones_lapas.vairuotojas,
keliones_lapas.vairuotojas2,
keliones_lapas.vairuotojas3,
keliones_lapas.vairuotojas4,
keliones_lapas.marsrutas,
klientai.firmos_pavadinimas AS uzsakovas,
uzsakovo_uzs_nr,
valiutos.valiuta AS frachto_valiuta,
uzsakymas.vadybininkas,
uzsakymas.skyrius,
uzsakymas.frachtas_suma,
uzsakymas.pavadinimas,
uzsakymas.uzsakymo_id,
uzsakymas.reg_data,
uzsakymas.pastabos AS uzs_pastabos,
uzsakymas.statusas AS uzsakymo_statusas,
sask_ist.serija,
sask_ist.sask_nr,
sask_ist.id AS sask_id,
sask_ist.suma,
sask_ist.valiuta,
sask_ist.kursas AS sask_ist_kursas,
sask_ist.apmoketi_iki,
sask_ist.atidejimas,
issiuntimo_data,
sask_ist_apmokejimas.suma AS ist_apm_suma,
sask_ist_apmokejimas.valiuta AS ist_apm_valiuta,
sask_ist_apmokejimas.kursas AS ist_apm_kursas,
sask_ist_apmokejimas.id AS ist_apm_id,
klientu_pakr_vietos.pavadinimas AS muitines_pavadinimas,
klientu_pakr_vietos.miestas AS muitines_miestas,
klientu_pakr_vietos.adresas AS muitines_adresas,
kokio_krovinio_dalis,
krovinys_konsoliduotas,
kroviniu_tipai.pavadinimas AS krovinio_pavadinimas,
kroviniai.pasikrovimo_data,
kroviniai.pristatymo_data,
kroviniai.uzsakovo_krovinio_nr,
kroviniai.id AS krovinio_id,
svoris_t,
ldm,
turis,
paleciu_skaicius,
vnt,
temperature,
kroviniai.konteinerio_nr,
kroviniai.pakr_vietos_id AS kr_pakr_vietos_id,
kroviniai.iskr_vietos_id AS kr_iskr_vietos_id,
kroviniai.pakr_salis AS kr_pakr_salis,
kroviniai.iskr_salis AS kr_iskr_salis,
kroviniai.pakr_miestas AS kr_pakr_miestas,
kroviniai.pakr_regionas AS kr_pakr_regionas,
kroviniai.iskr_regionas AS kr_iskr_regionas,
kroviniai.iskr_miestas AS kr_iskr_miestas,
kroviniai.ismuitinimo_data AS ismuitinimo_data,
kroviniai.uzmuitinimo_data AS uzmuitinimo_data,
kroviniai.pasienio_postas AS pasienio_postas,
kroviniai.ismuitinimo_vieta AS ismuitinimo_vieta,
statusai.pavadinimas AS st_pavadinimas,
st_uzsakymai.id AS st_id,
st_salys.salis AS st_salis,
st_uzsakymai.data AS st_data,
st_uzsakymai.laikas AS st_laikas,
st_uzsakymai.ivykio_pastabos_sutr AS st_pastabos_sutr,
st_uzsakymai.ivykio_pastabos AS st_pastabos,
st_keliones_lapas.reiso_pavadinimas AS st_reiso_pav,
vairuotojai.vardas AS sq_vardas,
priekabos.masinos_nr AS sq_priekaba
FROM uzdaviniai
LEFT JOIN priekabos
ON priekabos.id = uzdaviniai.uzdavinio_priekaba
LEFT JOIN users AS uzdav_users
ON uzdav_users.id = uzdaviniai.kam_sukure_vadyb
LEFT JOIN salys AS pakrov_salis
ON pakrov_salis.id = uzdaviniai.pakr_salis
LEFT JOIN salys AS iskrov_salis
ON iskrov_salis.id = uzdaviniai.iskr_salis
LEFT JOIN uzsakymas
ON uzdaviniai.uzsakymo_id = uzsakymas.uzsakymo_id
LEFT JOIN uzd_kur_vykdytas
ON uzdaviniai.id = uzd_kur_vykdytas.uzdavinio_id
LEFT JOIN keliones_lapas
ON keliones_lapas.reiso_nr = uzd_kur_vykdytas.reiso_nr
LEFT JOIN st_uzsakymai
ON st_uzsakymai.uzdavinio_id = uzdaviniai.id
LEFT JOIN statusai
ON statusai.id = st_uzsakymai.statuso_id
LEFT JOIN salys AS st_salys
ON st_salys.id = st_uzsakymai.salis
LEFT JOIN keliones_lapas AS st_keliones_lapas
ON st_keliones_lapas.reiso_nr = st_uzsakymai.reiso_nr
LEFT JOIN vairuotojai
ON vairuotojai.id = keliones_lapas.vairuotojas
LEFT JOIN sask_ist_uz_ka
ON sask_ist_uz_ka.uzsakymo_id = uzsakymas.uzsakymo_id
LEFT JOIN sask_ist
ON sask_ist.id = sask_ist_uz_ka.sask_id
LEFT JOIN sask_ist_apmokejimas
ON sask_ist.id = sask_ist_apmokejimas.sask_id
LEFT JOIN uzsakymo_kroviniai
ON uzsakymas.uzsakymo_id = uzsakymo_kroviniai.uzsakymo_id
LEFT JOIN kroviniai
ON kroviniai.id = uzsakymo_kroviniai.krovinio_id
LEFT JOIN klientu_pakr_vietos
ON klientu_pakr_vietos.id = kroviniai.ismuitinimo_vieta
LEFT JOIN klientu_pakr_vietos AS iskr_vietos_uzd
ON iskr_vietos_uzd.id = uzdaviniai.pakr_vietos_id
LEFT JOIN salys
ON salys.id = klientu_pakr_vietos.salis
LEFT JOIN cmr_kroviniai
ON kroviniai.id = cmr_kroviniai.krovinio_id
LEFT JOIN cmr
ON cmr.id = cmr_kroviniai.cmr_id
LEFT JOIN cmr_panaudojimas
ON cmr_panaudojimas.cmr_id = cmr_kroviniai.cmr_id
AND keliones_lapas.reiso_nr = cmr_panaudojimas.reiso_nr
LEFT JOIN kroviniu_tipai
ON kroviniu_tipai.id = kroviniai.krovinio_pavadinimas
LEFT JOIN klientai
ON klientai.id = uzsakymas.kliento_id
LEFT JOIN valiutos
ON valiutos.id = uzsakymas.frachtas_valiuta
WHERE 1 = 1
AND ( `uzdaviniai`.`pasikrovimo_data` BETWEEN
'2019-07-08' AND '2019-07-08 23:59:59'
)
ORDER BY uzdaviniai.pasikrovimo_data DESC
LIMIT 300
As you can see there is many left join, statements.
4. Result
What i want is some help what can i do with this piece of crap or some recommendation what can i change. As i expect these query will take more and more time to execute.
If the query is fast when executed directly in mysql console, then the query has no problem at all, and what is slow is the php code that uses the results of the query, php code that you don't show and that you should revise/post here.
If the query is slow even in mysql console, then the problem can be the size of the master/joined tables (but this may be resolved by relaxing the memory limits of the mysql server and/or adding ram to the server), or could be non correct indexing of the joined tables, since any LEFT JOIN needs the joined table to be indexed on the field you use to join it (and this could be resolved by creating the correct indexes on the joined tables).
Consider changing your
WHERE 1 = 1
AND ( `uzdaviniai`.`pasikrovimo_data` BETWEEN
'2019-07-08' AND '2019-07-08 23:59:59'
)
TO
WHERE uzdaviniai.pasikrovimo_data BETWEEN
'2019-07-08' AND '2019-07-08 23:59:59'
and let us know results (with the backticks), please.
This query was supposed to return me four rows: which are four people with status 50 (which, in the application means "maternity leave"). But it returns only one.
On HeidiSQL the query doesn't even run because it displays a
syntax error on line 13:
(...)
corresponds to your MariaDB server version for the right syntax to use near 'a.id_regiao = '$id_regiao'
AND a.cod_status = 50
AND a.status' at line 13 */"
Here is the query. I'm slowly becoming familiar with sql statements and i did search a lot on SO before asking it:
//SELECTING PROJECT DATA
$query = "SELECT b.id_clt,b.nome AS nome_clt,
a.id_evento AS a_id_evento,a.data AS a_data,a.data_retorno AS a_data_retorno,
c.id_evento AS c_id_evento,c.data AS c_data,c.data_retorno AS c_data_retorno,
(SELECT nome FROM projeto WHERE id_projeto = a.id_projeto) AS nome_projeto,
(SELECT nome FROM curso WHERE id_curso = b.id_curso) AS nome_curso,
DATE_FORMAT(a.data,'%d/%m/%Y') AS a_data_br,
DATE_FORMAT(a.data_retorno,'%d/%m/%Y') AS a_data_retorno_br,
DATE_FORMAT(c.data,'%d/%m/%Y') AS c_data_br,
DATE_FORMAT(c.data_retorno,'%d/%m/%Y') AS c_data_retorno_br
FROM rh_eventos AS a
INNER JOIN rh_clt AS b ON (a.id_clt = b.id_clt AND a.cod_status = 50)
LEFT JOIN rh_eventos AS c ON (b.id_clt = c.id_clt AND c.cod_status = 54)
WHERE $cond_projeto a.id_regiao = '$id_regiao'
AND a.cod_status = 50
AND a.status = 1
AND NOW() BETWEEN a.data AND a.data_retorno
ORDER BY nome_projeto,b.nome;";
The problem is here in the query:
WHERE $cond_projeto a.id_regiao = '$id_regiao'
This inserts a variable (or maybe a full test?) without proper syntax. If it is a variable, include the table's column name in the criterium. If it is a full test, include AND like so:
WHERE $cond_projeto AND a.id_regiao = '$id_regiao'
Beware though! Use prepared statements, your code now appears to be vulnerable to SQL injection attacks (and those are not to be trifled with).
Here is the query, (as seen by using an echo before it) . I can see the output on heidsql now. Now its better for us to check it:
SELECT b.id_clt,b.nome AS nome_clt,
a.id_evento AS a_id_evento,a.data AS a_data,a.data_retorno AS a_data_retorno,
c.id_evento AS c_id_evento,c.data AS c_data,c.data_retorno AS c_data_retorno,
(SELECT nome FROM projeto WHERE id_projeto = a.id_projeto) AS nome_projeto,
(SELECT nome FROM curso WHERE id_curso = b.id_curso) AS nome_curso,
DATE_FORMAT(a.data,'%d/%m/%Y') AS a_data_br,
DATE_FORMAT(a.data_retorno,'%d/%m/%Y') AS a_data_retorno_br,
DATE_FORMAT(c.data,'%d/%m/%Y') AS c_data_br,
DATE_FORMAT(c.data_retorno,'%d/%m/%Y') AS c_data_retorno_br
FROM rh_eventos AS a
INNER JOIN rh_clt AS b ON (a.id_clt = b.id_clt AND a.cod_status = 50)
LEFT JOIN rh_eventos AS c ON (b.id_clt = c.id_clt AND c.cod_status = 54)
WHERE a.id_regiao = '1' AND a.cod_status = 50
AND a.status = 1
AND NOW() BETWEEN a.data AND a.data_retorno ORDER BY nome_projeto,b.nome;
I can now see the output on heidsql, though i still cant figure out why it doesent bring the other thre rows.
I have used this code to get definitions:
//assuming you've connected to your MySQL db
$word=$_GET['s']; //This variable stores the value given through url
if (ctype_alpha($word)){ // If it's alphabetical
$word_clean=mysql_real_escape_string($word); //Sanitize it for MySQL
}else{
//Not a valid word, error handle
exit();
}
$query='SELECT wordno FROM word WHERE lemma=`$word_clean` LIMIT 1';
$result=mysql_query($query);
$query='SELECT synsetno FROM sense WHERE wordno=`$wordno`';
$query='SELECT definition FROM synset WHERE synsetno=`$synset`';
BUT NOW I want to get synonyms and similar of that word ($word);
SELECT a.lemma, c.definition
FROM word a
INNER JOIN sense b
ON a.wordno = b.wordNo
INNER JOIN synset c
ON b.synsetno = c. synsetno
WHERE a.lemma = 'valueHere'
To fully gain knowledge about joins, kindly visit the link below:
Visual Representation of SQL Joins
A fast way to get a synonym/similar word using wordnet v3.0 with SQL:
SELECT w.lemma
FROM words AS w
LEFT JOIN senses AS s ON s.wordid = w.wordid
LEFT JOIN senses AS s2 ON s2.synsetid = s.synsetid
LEFT JOIN words AS w2 ON w2.wordid = s2.wordid
WHERE w.lemma <> 'coder'
AND w2.lemma = 'coder'
GROUP BY w.lemma
ORDER BY s.synsetid
I need to output the following query as csv.
I can easily write php logic to transpose the rows to columns from my group_concat column
However I am keen to keep as much of the data part in the database and minimize the manipulations on the php side.
I am experimenting with the two columns below the group_concat in the query.
The problem is the abundance value also returns for life_stage column. If there is no way around this other than manipulating the group_concat key values then that's fine, I just wanted to double check. Thanks in advance
SELECT
`tr`.`tr_id_pk` as 'RecordKey',
`t`.`tax_name` as `TaxonName`,
`tr`.`tr_date` as 'Date',
`s`.`si_name` as 'SiteName',
`tr`.`tr_grid_reference` as 'GridReference',
`tr`.`tr_is_site_grid` as 'IsSiteGrid',
`r`.`rec_name` as 'Recorder',
`r`.`rec_email` as 'RecorderEmail',
`tr`.`tr_comment` as 'RecordComment',
`tr`.`tr_last_update` as 'LastUpdated',
`tr`.`tr_form_key` as 'FormKey',
`c`.`co_name` as 'County',
`vc`.`vc_name` as 'ViceCounty',
`h`.`hab_name` as 'Habitat',
GROUP_CONCAT(DISTINCT CONCAT_WS('=', `ra`.`ra_name`, `rad`.`rad_value`)) as 'RecordAttributeKeyValuePairs',
`rad`.`rad_value` AS `abundance`,
`rad`.`rad_value` AS `life_stage`
FROM
`taxon_record`as `tr`
INNER JOIN
`taxon`as `t` ON `tr`.`tax_id_fk` = `t`.`tax_id_pk`
INNER JOIN
`recorder`as `r` ON `tr`.`rec_id_fk` = `r`.`rec_id_pk`
INNER JOIN
`site`as `s` ON `tr`.`si_id_fk` = `s`.`si_id_pk`
LEFT JOIN
`county`as `c` ON `tr`.`co_id_fk` = `c`.`co_id_pk`
LEFT JOIN
`vice_county`as `vc` ON `tr`.`vc_id_fk` = `vc`.`vc_id_pk`
LEFT JOIN
`habitat`as `h` ON `tr`.`hab_id_fk` = `h`.`hab_id_pk`
LEFT JOIN
(`record_attribute_data`as `rad`
INNER JOIN `record_attribute`as `ra` ON (`rad`.`ra_id_fk` = `ra`.`ra_id_pk`)) ON (`tr`.`tr_id_pk` = `rad`.`tr_id_fk`)
WHERE
`r`.`rec_email` = 'some_email#somewhere.com'
GROUP BY `tr`.`tr_id_pk`;
What you wish to do is known as "pivoting" your data and is something for which some other RDBMS have native support, but MySQL does not (by design, as the developers feel that such manipulations belong in the presentation layer).
However, as you've hinted at, you can construct a rather horrible MySQL query to perform the pivoting operation manually (one needs to join the attributes tables to the query once for each output column):
SELECT tr.tr_id_pk, abundance, life_stage -- etc.
FROM taxon_record AS tr
LEFT JOIN (
SELECT rad.tr_id_fk, rad.rad_value AS abundance
FROM
record_attribute_data ra JOIN record_attribute rad
ON rad.ra_id_fk = ra.ra_id_pk
WHERE ra.ra_name = 'abundance'
) AS tAbundance ON tAbundance.tr_id_fk = tr.tr_id_pk
LEFT JOIN (
SELECT rad.tr_id_fk, rad.rad_value AS life_stage
FROM
record_attribute_data ra JOIN record_attribute rad
ON rad.ra_id_fk = ra.ra_id_pk
WHERE ra.ra_name = 'life_stage'
) AS tLife_Stage ON tLife_Stage.tr_id_fk = tr.tr_id_pk
-- etc.
If you choose to go down this path, you can make your life slightly easier by generating this query using either a looping construct in PHP or a prepared statement in MySQL.
Is the problem that you are fetching the same column twice under different names?:
`rad`.`rad_value` AS `abundance`,
`rad`.`rad_value` AS `life_stage`
Looks like you'll always get the same thing for abundance and life_stage that way.
I am trying to perform a query in a PHP script. The query works fine in my MySQL client however it does not seem to working within my code. I am using PDO. I am thinking it might have limitations, because it seems to work fine with a less complicated query.
Here is the query:
SELECT D.status, D.createdBy, D.createDate, D.modifiedBy, D.modifiedDate,D.IPAddress, D.adminStatus, D.campus, D.buildingID, D.deviceShortName, D.distributionID, D.networkKey, D.deviceName, D.test, D.pkDevices, D.DNSRule, D.Domain, D.DNSOverride, D.noDNS, D.pkModel, DM.Model, DM.pkManufacturer, M.manufacturer FROM Devices AS D INNER JOIN DeviceModel AS DM ON D.pkModel = DM.pkModel INNER JOIN Manufacturer AS M ON DM.pkManufacturer = M.pkManufacturer WHERE D.status = '1' AND D.adminStatus = 'Active' ORDER BY D.deviceName
Here is where I am trying to call it in my script:
$dbhDevices = newPDO('mysql:host='.$_SESSION['OpsDBServer'].'.ops.tns.its.psu.edu;dbname='.$_SESSION['OpsDB'], $_SESSION['yoM'], $_SESSION['aMa']);
$sqlDevices = "SELECT D.status, D.createdBy, D.createDate, D.modifiedBy,
D.modifiedDate, D.IPAddress, D.adminStatus, D.campus, D.buildingID,
D.deviceShortName, D.distributionID, D.networkKey, D.deviceName, D.test,
D.pkDevices, D.DNSRule, D.Domain, D.DNSOverride, D.noDNS, D.pkModel, DM.Model,
DM.pkManufacturer, M.manufacturer
FROM Devices AS D
INNER JOIN DeviceModel AS DM ON D.pkModel = DM.pkModel
INNER JOIN Manufacturer AS M ON DM.pkManufacturer = M.pkManufacturer
WHERE D.status = '1' AND D.adminStatus = 'Active' ORDER BY D.deviceName";
foreach ($dbhDevices->query($sqlDevices) as $rowDevices)
{
Again, the query does work with the MySQL client.
try enabling errors if haven't done already:
error_reporting(E_ALL);
$dbhDevices->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
In the older versions of PDO usage you have to "initialize" your PDO variable when you declare it for some reason. Try putting a line before this code that generically initializes $dbhDevices and see if that does the trick. I have my doubts because you say it works fine with less complicated queries but it's worth a try.
I got it working by using a LEFT JOIN instead of an INNER JOIN. Strange, but it is working.