Tauākī SQL Basic

tangohia paerewa SQL i roto i 1992, me te tonu i roto i te whakamahi i ēnei rā. E kua waiho e ia i te paearu, mo maha ngā pūnaha whakahaere pātengi raraunga. O te akoranga, te whakamahi i ētahi o ngā kaihanga o ratou ake tikanga o te paerewa. Otiia i roto i tetahi pūnaha, i reira e tonu nga wae matua - tauākī SQL.

whakataki

Mā te tauākī SQL i roto i te pātengi raraunga puta tepu whakahaere uara me ratou faaineineraa no te tātari anō, me te whakaatu. Ko ratou he huinga o ngā kupu matua, i nei e matau i te pūnaha aha ki te mahi ki nga raraunga.

Tautuhi e rave rahi ngā kāwai o ngā tauākī SQL:

• whakamāramatanga o ahanoa pātengi raraunga;
• raweke uara;
• tiaki me te whakahaere;
• tawhā wātū;
• Mōhiohio e pā ana ki te turanga;
• SQL pateko;
• SQL hihiri.

tauākī SQL mō te te whawhe raraunga

Tenei kāwai ngā te kupu matua ki e taea e koe te whakahaere i te whakanohonga o ngā uara i te pātengi raraunga.

WHAKAURUA. Kōkuhu ai he rarangi i roto i te ripanga tīariari. Ka taea te whakamahi i te reira rite te uara kotahi ranei maha, tautuhia e te tetahi huru. Hei tauira:

WHAKAURUA INTO

te ingoa ripanga (tīwae 1 ingoa, ingoa o te tīwae 2)

Uara (uara 1 uara 2).

Hei whakamahi i te kaiwhakahaere tauākī SQL WHAKAURUA ki uara maha, te whakamahi i te wetereo e whai ake nei:

WHAKAURUA INTO

ingoa 1 tepu (ingoa o te tīwae 1, tīwae ingoa 2)

Tīpakohia ingoa tīwae 1, ingoa o te tīwae 2

MEI ingoa ripanga 2

HEA ingoa 2.imya tepu tīwae 1> 2

Tenei uiui kōwhiria e te raraunga katoa i roto i te Ripanga 2, i te mea nui ake i te 2 mō te 1 tīwae me te whakapiri ratou ki te tuatahi.

WHAKAHOU. Ka rite ki te ingoa titau, tenei tauākī whakahōu te raraunga uiui SQL i roto i te ripanga tīariari i runga i te tetahi pūtake.

tauira:

WHAKAHOU ingoa ripanga 1

ingoa WHAKARITE tīwae = 2 "Basil"

HEA tepu ingoa 1.imya tīwae 1 = 1

Tenei Basil hanganga uara makona rarangi katoa e whakatau i te tau 1 i roto i te tīwae tuatahi.

DELETE. Muku ai i te raraunga i te ripanga. Ka taea e koe te whakapūtā tetahi huru ki te tango i nga rarangi katoa ranei.

MUKU MEI ingoa ripanga

HEA ingoa tablitsy.imya tīwae 1 = 1

Ka muku i te uiui i runga ake nga raraunga katoa i te pātengi raraunga ki te uara tetahi i roto i te tīwae tuatahi. Here te pehea koe e taea e ūkui i te tepu katoa:

MUKU FROM ingoa tepu.

Next he tika ki te korero e pā ana ki te tauākī Tīpakohia. Ko ia tetahi o te nui tino, na ka whai ia ki te horo'a i te pene motuhake.

tauākī Tīpakohia

Ko te whakaaro matua o Tīpakohia - kōwhiringa o ngā raraunga rite ki etahi tikanga. Ko te hua o tona mahi he tonu he tepu hou ki raraunga tīpakohia. MS tohutūmahi SQL Tīpakohia taea te whakamahi ki te taumaha tono rerekē. Na reira, me ki taua mea, ka taea e koe te whakaaro i ētahi atu kupumatua hāngai ana.

Hei tīpako katoa o te tohu raraunga "*" Kei te whakamahia i te tepu ngā.

Tīpakohia *

MEI ingoa ripanga 1

Ko te hua o tenei uiui ka waiho hei kape tangohia o te tepu 1.

A he tikina e konei HEA huru e faaho'i i roto i te Ripanga 1, ngā uara katoa nui atu i te 2 i roto i te tīwae 1.

Tīpakohia *

MEI ingoa ripanga 1

HEA ingoa 1.imya tepu tīwae 1> 2

Ka taea hoki e koe te whakapūtā i te tīpakonga e kua hiahiatia anake etahi tīwae.

ingoa ripanga Tīpakohia 1.imya tīwae 1

MEI ingoa ripanga 1

Ko te hua o tenei uiui e rārangi katoa ki uara o tīwae 1. Mā te ngā MS SQL taea te waihanga i tona tepu ake, i roto i te akoranga o whakakapi, te tātai me te whakakapi etahi uara.

Tīpakohia

ingoa ripanga 1.imya tīwae 1

ingoa ripanga 1.imya tīwae 2

ingoa ripanga 1.imya tīwae 3

«=» AS EQ

ingoa ripanga 1.imya tīwae 2 o te ingoa ripanga * 1.imya tīwae 3 AS Tapeke

MEI ingoa ripanga 1

Tenei uiui ngali matatini fetches nga uara katoa o Ripanga 1, a ka hanga he tīwae hou, me te EQ Tapeke. Tuatahi tomo "+" tohu, i roto i te tīwae raraunga tuarua o te hua 2 me 3. tenei hua e taea te kanohi rite te tepu, mo te matauranga ka pehea te mahi i te reira:

tīwae 1	tīwae 2	tīwae 3	EQ	Tapeke
Ingoa Hua 1	10	50	+	500
Ingoa Hua 2	15	100	+	1500

Ki te kei te whakamahi koe i te tauākī Tīpakohia, ka taea e noho tonu koutou tono raraunga i runga i tetahi papa whenua. whakamahi te reira i te kupu Tuhinga BY.

Tīpakohia

ingoa ripanga 1.imya tīwae 1

ingoa ripanga 1.imya tīwae 2

ingoa ripanga 1.imya tīwae 3

MEI ingoa ripanga 1

Tuhinga BY ingoa tīwae 2

Ka titiro te tepu hua rite tenei:

tīwae 1	tīwae 2	tīwae 3
1	1	54
3	2	12
7	3	100
2	5	1

Ko te, te rārangi katoa kua tāuta i roto i te tikanga taua e piki ana i te tīwae 2 uara.

taea hoki te whiwhi Raraunga i tepu maha. Hoki mārama, me whakaaro tuatahi koe e whai ratou tokorua, ko etahi i roto i te pātengi raraunga:

Ripanga "kaimahi"

tau	ingoa	ingoa
1	Vasya	Vasin
2	Petya	Petin

Ripanga "utu"

tau	auau	kiia ki
1	1	10000
2	0.5	3500

Na e hiahia ana koe, pēnei i te hono i te papa e rua ki te tiki i ngā uara noa. Mā te tauākī SQL taketake taea te mahi i te reira e whai ake:

Tīpakohia

Sotrudniki.Nomer

Sotrudniki.Imya

Zarplata.Stavka

Zarplata.Nachisleno

MEI kaimahi utu

HEA Sotrudniki.Nomer = Zarplata.Nomer

He he tikina i papa rerekē e rua o ngā uara, piri i te tatau. Ko te hua ko te huinga e whai ake nei o te raraunga:

tau	ingoa	auau	kiia ki
1	Vasya	1	10000
2	Petya	0.5	3500

He iti ake e pā ana ki te Tīpakohia. Mā te mahi whakahiato

Ko tētahi o nga tauākī SQL Tīpakohia taketake e ahei te hua te tahi mau tātaitanga i roto i te tauira. Ki te mahi i tenei, whakamahi ia etahi mahi me ngā tātai.

Hei tauira, ki te tiki i te maha o ngā pūkete i te tepu "kaimahi", e hiahia ana koe ki te whakamahi i te rapu:

COUNT Tīpakohia (*) AS N

MEI kaimahi

Ko te hua ka waiho he tepu ki tetahi tīwae me te uara.

N

2

Ka taea te whakamahi mahi i roto i uiui e tātai te moni, mōrahi me ngā uara mōkito, me te toharite. Ki te mahi i tenei, kei te whakamahia kupumatua SUM, MAX, Min, AVG.

Hei tauira, he mea e tika ana ki te pupuri i te tauira o te tepu "utu" mohiotia kua:

tau	auau	kiia ki
1	1	10000
2	0.5	3500

Ka taea e koe te tono i te tono taua a kite mea e tupu:

Tīpakohia

SUM (Zarplata.Nachisleno) AS Tapeke

MAX (Zarplata.Nachisleno) AS MAX

Min (Zarplata.Nachisleno) AS min

AVG (Zarplata.Nachisleno) AS SRED

MEI utu

Ka waiho i te tepu whakamutunga e whai ake:

Tapeke	MAX	min	SRED
13500	10000	3500	-6750

Ko te te ara, ka taea e koe te whiriwhiri i te pātengi raraunga i te uara tika i runga i te rere ki te mahi i te tātai o ngā mahi.

Union, pūtahitanga me te rerekētanga

Whakakotahitia uiui maha i roto i te SQL

Tīpakohia Sotrudniki.Imya

MEI kaimahi

HEA Sotrudniki.Nomer = 1

UNION

Tīpakohia Sotrudniki.Imya

MEI kaimahi utu

HEA Zarplata.Nomer = 1

kia whanau te reira i roto i te ngakau e i roto i tenei tepu rōpū me kia hototahi. E ko, i te taua maha o tīwae.

Ko te wetereo o te tauākī Tīpakohia me te tukanga mō te tukatuka

Ko te mea tuatahi Tīpakohia whakatau te rohe i nei e tangohia ai te raraunga. Ki te mahi i tenei, te whakamahi i te kupu matua MEI. Ki te kore tohua, aha ki te whiriwhiri.

ka taea e koe te whakaatu i te tauākī SQL HEA. Ki te awhina o Tīpakohia rere i roto i ia rarangi o te tepu, me te taki i te raraunga mō te tautukunga ki te huru.

Ki te uiui e te GROUP BY, na reira ko te whakarōpūtanga o ngā uara o ēnei tawhā.

Ngā ki whakarite raraunga

E ratou e rave rahi momo. I roto i te SQL ngā whakarite e taea whakamātau momo rerekē o ngā uara.

• "=". Tohu, ka rite ki a koutou kia imi, te taurite o te kīanga e rua. Hei tauira, kua kua reira i whakamahia i roto i te tauira i runga - HEA Zarplata.Nomer = 1.

• ">". Nui-i te tohu. Ki te he nui te uara o te taha maui o te faaiteraa na te TRUE arorau e hoki mai, ka tutaki i te huru te.

• "<". Iti iho i te tohu. Whakataka te tohutūmahi o mua.

• Tohu o "<=" me "> =". rere ke te reira i ngā ohie atu me iti iho ko e ki tauwhakaarotau rite he pono hoki huru.

• "<>". e kore ahau e tiaki. whakaaro te huru te TRUE, ki te kahore e rite ki tetahi kotahi anake te operand. Kei a ia tetahi atu tikanga - "! =".

penei ano

Whakamāoritia taea e tenei kupu matua rite "rite." Penei ano whakamahia kaiwhakahaere i roto i SQL te āhua i runga i te parau tumu taua - Rere te uiui i te tātauira. E ko, taea reira ki a koutou te whakawhānui i te raraunga tauira i te pātengi raraunga mā te whakamahi i kīanga auau.

Hei tauira, ka whakaturia ki te tūmahi taua: i te turanga "tokotoko" mohiotia kua ki te tiki i te iwi katoa nei ingoa mutu ki "ahau". Na e taea te titoa te tono e whai ake:

Tīpakohia *

MEI kaimahi

HEA Ingoa penei ano `% I`ll

tohu ōrau i roto i tenei take te tikanga te kanohi, e ko, tetahi huru, me to ratou tokomaha. A i roto i te pukapuka, "ahau» SQL whakatau e ki te pūāhua whakamutunga kia taua ara.

CASE

Tenei Tūmau tauākī SQL ko te whakatinanatanga o te whiriwhiri maha. rite te reira i te tauākī whakakā i roto i maha reo hōtaka. tauākī CASE i SQL mahi i te mahi i runga i te maha o ngā āhuatanga.

Hei tauira, tīpako koe i te tepu "utu" mōrahi me uara mōkito.

tau	auau	kiia ki
1	1	10000
2	0.5	3500

Na e taea te titoa te tono e whai ake:

Tīpakohia *

MEI utu

HEA CASE, no te tīpako MAX (whakatupato) Na ka Mōrahi

No te tīpako min (whakatupato) Na ka Mōkito

hua END

i roto i te tīwae "whakatupato" i roto i tenei horopaki, titiro te pūnaha mo te uara mōrahi me te mōkito. Na, te whakamahi i te mara END hanga "tapeke", ka e kia takiuru i roto i te "te mōrahi" ranei "mōkito" i runga i te hua o te huru rānei.

E te ara, i roto i te SQL reira ko te ahua atu kiato o te CASE - COALESCE.

tautuhinga raraunga

Tenei tirohanga taea ki a koe te kawe i roto i te momo o te huri papa - te waihanga, muku, whakarerekē, ka mahi ki te taupū.

Ko te tetahi tuatahi, i te mea utu whakaaro - FAU TABLE. e ia tetahi mea atu atu i te hanga i te tepu. Ki te koe pato noa FAU uiui TABLE, kahore e tupu, no te mea e hiahia ana koe ki te whakapūtā te maha atu tawhā.

Hei tauira, ki te waihanga i te tepu maheni "Kaimahi" e hiahia ana ki te whakamahi i te whakahau:

FA'U kaimahi TABLE

(Tau ID (10) Kāore i korengia

varchar Ingoa (50) Kāore i korengia

Ingoa Last varchar (50) Kāore i korengia)

I roto i tenei tono, i roto i te te 'tautuhi tonu ingoa mara, me o ratou momo, me te ranei e taea e te reira i korengia.

TULUTĀ TABLE

Mahi he mahi kuware - tango tepu mea. He he kōwhiringa atu ki te vai. absorbs te reira i te hapa, ka muku, ki te kore e tīariari te tepu hiahiatia. Tauira o te whakamahi:

TULUTĀ TÜTOHI Employees ki te vai.

Waihangaia he Index

I roto i te SQL, i reira te mea he pūnaha o kuputohu, e taea te uru tere ki raraunga. I roto i te whānui, he mea he hononga e tohu ki te tīwae ngā. Waihanga i te taupū e taea e te tono ohie:

FA'U Index nazvanie_indeksa

ON nazvanie_tablitsy (nazvanie_stolbtsa)

Whakamahia tenei tauākī i roto i T-SQL, Oracle, PL SQL me maha atu tikanga hangarau.

ALTER TABLE

operator tino mahi ki te maha kōwhiringa. I roto i te whānui, i te huringa hua he whakamāramatanga hanganga me tepu tohatoha. whakamahia operator e i roto i Oracle SQL, Postgres, me te tini ke atu.

Ka inaianei Tohutoro kia te aroaro ki ngā kōwhiringa mā te whakamahi i ALTER TABLE.

• ADD. Te mauria i te tua o te tīwae i roto i te ripanga. Wetereo tenei ia: e whakarereketia TABLE ADD tip_hranimyh_dannyh nazvanie_stolbtsa nazvanie_tablitsy. Ka taea e whai i te tawhā ki te vai NOT, e pehi i te hapa, ki te mea kua hanga kē he tīwae;

• TULUTĀ. He tango tīwae. Ki te vai te oti ano, e ka whakaputa i te hapa e mea e kore e te tīariari te tīwae tonoa;

• Tuhinga. Whakamahia ki te whakaingoa i te ingoa mara tohua. te whakamahinga Tauira: e whakarereketia TABLE Tuhinga nazvanie_tablitsy OldName new_name;

• Whakarerekē. Ka huri tenei whakahau te momo o te tīwae ngā me huanga atu. A Kei te whakamahia te reira rite tenei: e whakarereketia TABLE whakarerekē Momoraraunga nazvanie_stolbtsa nazvanie_tablitsy huanga;

Waihangaia he VIEW

I roto i te SQL, i reira te mea he mea pēnei i te whakaaro. I roto i te poto, ko reira he ahua o te tepu mariko ki te raraunga. Kei te hanga e te reira i rite ki te hua o te tauira mā te whakamahi i te reo SQL Tīpakohia tauākī. Ka taea e whakaaro rāhui i te uru ki te pātengi raraunga ki te huna ia ratou, ki te whakakapi i te ingoa tīwae tūturu.

Ko te tukanga o te waihanga puta i te rapu ohie:

Waihangaia he VIEW ingoa view AS Tīpakohia MAI * ingoa ripanga

kia tango tīpako wahi rite te pātengi raraunga katoa rite te katoa, a i roto i te tetahi huru.

He iti e pā ana ki te āhuatanga

I roto i te SQL maha whakamahi uiui rerekē mahi hanga-i roto i e tukua ki a koutou te taunekeneke ki te raraunga, me te tahuri ia ratou i runga i te ngaro. he utu whakaaro ratou i te reira, kia rite ki te hunga he wāhanga o te reo hanganga ratou.

• Tatau. Hua tatau rarangi tāurunga ranei i roto i te ripanga ngā. Ka rite ki te kōwhiringa, ka taea e koe te whakapūtā te ingoa tīwae, na ka tangohia nga raraunga i ia. COUNT * Tīpakohia MEI kaimahi;

• AVG. E pā ana tēnei āhuatanga anake ki tīwae ki raraunga tau. Ko tōna hua ko te faaotiraa o te tauhanga o ngā uara katoa;

• Min ko MAX. Kua ēnei mahi e whakamahia ana i roto i tenei tuhinga. tautuhi ratou te mōrahi me uara mōkito o tīwae mea;

• SUM. E mea ohie - Tātaitia te mahi te moni o uara i roto i te tīwae. Kei te whakamahia te reira i anake mo te momo raraunga tau. Tāpiri i te tawhā tono motuhake, ka tapiritia anake ki ngā uara motuhake;

• Rauna. Taumahi whakaawhiwhi ira tau hautanga. Ko te wetereo whakamahia e te ingoa tīwae me te maha o nga wahi-ira;

• Len. He mahi kuware e Tātaitia te roa o te tīwae. Ko te hua ka waiho he tepu hou e whakaatu ana i te maha o ngā pūāhua;

• NOW. whakamahia ana tēnei kupu matua te ki te tātai i te rā o nāianei, me te wā.

ngā atu

He maha ngā tauira o te tauākī SQL he kupumatua e mahi ngā mahi iti, engari ahakoa nui faaohie tauira mahi pātengi raraunga ranei.

• AS. Kei te whakamahia te reira, ina e hiahia ana koe ki te e ngā whakarite i te hua o vahe te ingoa i tohua ki te tiki i te tepu.

• WAENGANUI. He taputapu rawa pepa mō te tīpako. tohu te reira i te whānuitanga o ngā uara, tae atu i te hiahia ki te whiwhi i te raraunga. Ka whiwhi te tawhā tāuru i me ki te whānuitanga tau te whakamahia;.

• NOT. Ko te operator homai te ritenga atu o te faaiteraa.

• Te popore. Tango raraunga i wahi turanga mea. Rerekē i te hunga ngā e ora raraunga muri tona whakamahi taea. He mea utu te tuhituhi e taea te whakatinanatanga o te marau i homai i roto i te SQL rerekē hei tikanga rerekē. Na i mua i tamata koe ki te whakamahi i te popore, maheni lelei ange ki te kōrero whakamārama.

• Tuhinga. Ka tautuhi te maha o ngā rārangi putanga. Ko te taa o te operator ko e te kei tonu reira i te mutunga. E te reira kotahi whakahauanga me kotahi tawhā kōwhiringa. tohu ana te tuatahi me pehea ki te maha nga rarangi ki nga raraunga i tīpakohia whakaatu. A ki te mea te tuarua, ka whakahaere te operator te whānuitanga e rua o uara.

• UNION. operator ratarata-kaiwhakamahi rawa ki te ngā uiui maha. Kua tutaki kē ia i roto i nga tauira o tenei i roto i tenei tuhinga. Ka taea e koe te whakaatu i te rarangi i tepu maha, UNION te whakakotahi ratou mo te whakamahi atu watea. Wetereo tenei ia: WHIRIWHIRI I column_name MEI tepu UNION Tīpakohia MEI tepu imya_drugogo_stolbtsa imya_drugoy. Ko te hua ko te tepu whakarāpopototanga o te titauraa kotahi.

• MATUA TUATAHI. Iritihia rite "kī tuatahi." Mau, whakamahia e taua kupu i roto i ngā rauemi tohutoro. Ko ia he pūtautuhi ahurei mo te rarangi. Kei te whakamahia te reira, pera me te tikanga, ka hanga i te tepu ki te tohu i te mara e ka i roto i te reira.

• TAUNOA. Just rite te operator o mua, whakamahia i roto i te whakatinanatanga o te hanga i te uiui. tautuhi te reira i te uara taunoa, ka e kia ki tonu i roto i te mara, ka te hanga ai.

He tohutohu ruarua ki te whakawhanake i tētahi tūāpapa mō te mahi ki te SQL

1. Korengia. maha wareware Beginners me kore noa hötaka i te faaineineraa o ngā tono e pā ana ki te wātea o ngā uara i korengia. Ka rite ki te hua, ki te waehere hapa ngokingoki ana i roto i, i te mea uaua te aru i roto i te tukanga patuiro. Na reira, ka hanga i te tepu, Me uara tauira tatau anō ranei ki te mutu, ka whakaaro, a ahakoa i korengia takanga tangohia te ki pūkete i roto i te rohe rapu.

2. Memory. I roto i tenei pepa i whakakitea tatou he maha o ngā mahi, e taea o te raveraa i etahi mahi. I roto i te whanaketanga o te anga ki te mahi ki te pātengi raraunga, ka taea e koe "tami" te tātai o ngā kīanga māmā ki te pūnaha pātengi raraunga. I roto i ētahi wā, homai tenei te whakanui nui i roto i te mahi.

3. Rāhuitanga. Ki te hiahia koe ki te tiki i te pātengi raraunga ki nga mano o nga rarangi e rua anake, ko reira e tika ana ki te whakamahi i ngā pērā i Tuhinga TOP ranei. Kahore he take ki te tiki raraunga i te tikanga o te anga o te whanaketanga reo.

4. Tūhono. Ki runga ki te taenga o ngā raraunga i te maha tepu, timata maha hötaka ki te whakaiti tahi ratou pūhera tikanga mahara. Ko te aha? I muri i te katoa, ka taea e hanga e koe he tono i roto i nei e waiho reira katoa reira. e kore koe e whai ki te tuhituhi waehere kotahi, ka waiho mahara atu i roto i te pūnaha.

5. Kōmaka. Ki te he reira taea ki te tono i te tikanga i roto i te tono, e ko, te ope DBMS, he mea e tika ana ki te whakamahi i te reira. Ka nui tenei whakaora i runga i ngā rauemi, ka te hōtaka, ratonga rānei.

6. He maha tono. Ki te whai koe ki te kōkuhu i te rota o ngā pūkete i roto i te raupapa, ka kia whakaaro arotautanga e pā ana ki whakaurua te raraunga pākete te kotahi tono. Ka neke ake ano tenei te mahi o te pūnaha katoa.

7. whakanohonga tupato o raraunga. I mua i te tuhi ake te hanganga turanga Me ki te whakaaro e pā ana ki te āhua o me mēnā he maha taua o tepu me mara e tika ana. Pea i reira ko te ara ki te ngā ratou, hoatu ake etahi ranei. Tino maha, te whakamahi i hötaka i te nui rawa o te raraunga e te whakamahia wahi, me te kore.

8. Momo. Hei whakaora wāhi me te hiahia rauemi ki kia tairongo ki nga momo o raraunga whakamahia. Ki te taea te tango e koe painga o te "taimaha" iti mo te momo o te mahara, whai koe ki te whakamahi i tona ingoa. Hei tauira, ki te mea i mohiotia he e i roto i tenei mara, ko kore e he uara tau nui 255, he aha te whakamahi o te 4-paita INT, ki te TINYINT reira 1 paita.

mutunga

Roto i te whakamutunga, kia tuhia te reira e hanganga te reo kei te pātai SQL te whakamahia tata nga wahi katoa inaianei - tukutuku, ratonga tukutuku, pūmanawa papamahi, tono pūkoro. Na reira, ka āwhina i SQL matauranga rāngai katoa o te whanaketanga.

Heoi, whakarerekē o paerewa reo Māori ētahi wā rerekē i ia atu. Hei tauira, kia whai ngā SQL PL turereo rerekē atu i roto i te Tūmau SQL. Na i mua i te tīmata koe whakawhanake ki tenei hangarau, he mea e tika ana ki te kia maheni ki reira e aratohu.

I roto i nga ritenga a muri, e taea e nui te taumahinga SQL me mahi, he pea ki te puta i te reira, na tenei whānuitanga ko rawa he wāhi whaihua mo tetahi kaihātepe.