I waenganui SQL: Tauira Whakamārama

A, no te mahi ki te pātengi raraunga tūhonohono i roto i nei Kei te rongoa raraunga i roto i tepu, kei te maha fehangahangai kaiwhakamahi ki te mahi o ngā uara tīpako ngā (kore whakaurua) i roto i te whānuitanga tetahi. taea reo SQL ki a koutou te tautuhi maha, e kia (e kore e) no ki te uara o ngā kōwhiringa rerekē - operator I roto i, rite operator, he huinga o ngā āhuatanga ake - iti iho, me te SQL mo I waenganui kaiwhakahaere. Ka arotahi Whakamārama me tauira i roto i tēnei tuhinga i runga i te putanga hou.

"I waenganui" kaiwhakahaere i roto i te SQL: here Wetereo

Mooni operator i waenganui i SQL a whakawhitia - "i roto i waenganui i". Ko tōna whakamahi hanga reira taea ki te whakaturia te rohe "me i" te mara ngā, me ki te taka te uara i muri i roto i te whānuitanga, na ka te paparangi kia whakatakotoria ki "True", a ka hinga te uara i roto i te tauira whakamutunga.

Ko te wetereo o te operator he tino māmā:

Ka rite ki a koutou e taea te kite, i muri i te kupu matua i waenganui ia koutou me whakapūtā te uara o te rohe o raro, ka AND, me te rohe o runga.

Tatau, he aha ngā momo o ngā raraunga taea te kaiwhakahaere te mahi i waenganui i SQL:

1. Ki te tau - tau tōpū, me te hautanga.
2. Ki te rā.
3. Ki te kuputuhi.

Meatia tenei i waenganui i he etahi peculiarities tauākī SQL. whiwhi tatou ki te mohio ratou:

1. A, no te mahi ki tau, me ngā rā o ngā uara rohe "me i" e ngā i roto i te tauira.
2. Me kia raro uara whānui iti iho i te rohe o runga, te kore e tetahi mea e whakaaturia, no te mea kahore he arorau pono te huru. Me tiaki Motuhake ki te kia, ka, hei utu o e ngā uara motuhake i roto i te taurangi huru.

e kore te, no te mahi ki te uara kuputuhi o te awhe o runga ngā i roto i te tauira, ki te kore te reira tautuhi rawa tika. whakaaro tatou i tenei āhuatanga i roto i te wāhanga e whai ake nei i roto i te taipitopito.

tau Tauira me rā i roto i te whānuitanga etahi

Whakapaia te tepu ki te kaiwhakahaere raraunga, mahi i roto i te whakahaere. Ka whai i te tepu i te hanganga e whai ake nei:

Whakakiia i roto i te ripanga i te raraunga e whai ake nei:

Puka te uiui SQL i waenganui, e e te tauturu ia ki a tatou te tīpako i nga kaimahi katoa e whai 2 ranei 3 tamariki:

Ko te hua ka e toru nga rarangi ki raraunga i runga i ngā kaimahi ki ngā ingoa whānau Shumilin, Tropnikov ko Avdeeva.

Na tīpako nga kaimahi riro i te 1 Kohitātea 2005 ki te 31 Hakihea 2016. Me kï reira e pātengi raraunga rerekē i roto i ngā huarahi rerekē tukua ki a koe te tuhi i roto i ngā o ngā rā. I roto i te nuinga o te wā, te rā o te ope ki te puka ra-marama-tau (atu watea ranei) ka tuhia i roto i kōrero kotahi rua ranei. Te DBMS MS Access rā Kei te tohu "#". Whakahaere i tēnei tauira te tika i runga i taua mea:

Ko te hua ka e rima kaimahi tīkina i roto i te wā whakakotahi.

Next, kia kite a te pehea te mahi i te reira i waenganui i aho SQL.

Mahi i roto i waenganui i aho

He raruraru tino noa e me e faatiti'aifarohia ka mahi ki nga ingoa o kaimahi - ko te hiahia ki te tīpako anake te hunga timata ki te tetahi reta nei ingoa. A tamata tatou ki mahia i te uiui, me te tīpako kaimahi timata ki te ingoa whakamutunga i te ki te B nei ingoa:

Ko te hua, ko te rite whai:

Ka rite ki a koutou e taea te kite, kihai i nga kaimahi e rua ki te ingoa i runga i te B reta i roto i te rārangi ngā. He aha te mea te take? Ko te meka Ko rite pehea te operator whakataurite aho o te roa taurite. Raina "B" ko string poto "Vinogradov" me ngāwari. Otira ka kōmaka pū ka mokowā pūāhua tere, me te ingoa o te tauira e kore e hinga. pātengi raraunga rerekē whakarato huarahi rerekē ki te whakaoti i tenei raruraru, engari ko reira maha te ara māmā ki te tohu i te tika o te pukapuka i muri o te tātai reta i roto i te awhe:

A, no te mahi ana, ka makona tatou i te hua rapu rawa.

vai tēnei mita anake ka mahi ki raraunga huru, engari whakaatu te reira e noa, no te mahi ki taua ngā ohie rite i waenganui i, whai koe ki te kia tupato.