SQL "nokuti Dummies": zvaunoda kuziva ruzivo?

To musi, "nokuti dummies" ari SQL makosi zvava dzakakurumbira. Zvinogona nyore chaizvo kutsanangura, nokuti kakawanda unogona kuwana vanonzi "simba" padandemutande mabasa munyika nhasi. Vane tefa mumuhara musoro uye dzinobva Databases. All programmers ruzivo vanenge vakasarudza kuzvipira pakusikwa nzvimbo, zvikurukuru zvakanyorwa kuti SQL kosi "nokuda dummies".

Sei kudzidza mutauro?

Chokutanga, SQL anodzidziswa kuti mberi kusikwa akasiyana-siyana zvikumbiro chimwe chezvinhu yakakurumbira zvevakomana injini Blogs - WordPress. Apfuudza ane zvidzidzo zvishomanana, iwe uchava kare kukwanisa kusika queries upi kunzwisisa, izvo chete rinosimbisa nyore mutauro.

Chii SQL?

Muronga Query Language, kana muronga Query Language, akasikwa aine chinangwa chimwe chete: kuona mhando data, kuvapa mukana kwavari uye kuvabata munguva pfupi zvikamu. Kana uchiziva SQL-kukosha, ipapo uchanzwisisa kuti Server ichi ndowenyika mitauro vanonzi "nonprocedural". Kureva kugona rayo kusanganisira chete kurondedzerwa chero zvinoriumba kana migumisiro kuti unoda kuona ramangwana panzvimbo. Asi programmer ichi haritauri musi chii chaizvo zviri kuitika kuti zvabuda. Mumwe chikumbiro chitsva mutauro uyu rudzi mamwe "superstructure." Kuti mune izvo zvavari vapinda mune Database, uye zvikumbiro huchazadzika.

Chii Matanho anogona kuitwa kushandisa mutauro uyu?

Pasinei ayo nyore, SQL Database unokubvumira kusika yakawanda kupfuura siyana zvikumbiro. Saka chii zvaungaita kana ukadzidza ichi zvirongwa mutauro unokosha?

• kusika zvakasiyana siyana matafura;
• kugamuchira, chitoro, uye yokugadziridza mashoko;
• kushandura urongwa mabwendefa yayo chete ungwaru;
• nokubatanidza akagamuchira mashoko mugomba chete chikwata;
• ngaaverenge akagamuchira mashoko;
• kudzivirira izere mashoko.

Iyo zvikwata zviri rakakurumbira mutauro uyu?

Kana ukasarudza kushanyira SQL makosi "nokuda dummies", ipapo muchapiwa kwemashoko akazara pamusoro mirayiro zvinoshandiswa mukusika queries nayo. Rakajairika nokure ndeinotevera:

1. DDL - ndiwo murayiro kutaura kuti mashoko. Rinoshandiswa rokusika, kuchinja uye zvinomuomera kuikanganwa zvakasiyana-siyana zvinhu zviri Database.
2. DCL - boka kuti Rinotarisira mashoko. Rinoshandiswa kupa kuwana vanoshandisa siyana kuti mashoko ari Database, uyewo kushandisa tafura kana maonero.
3. TCL - boka kuti Rinotarisira nekuve kwema. Chinangwa Its chikuru ndechokudzibatsira kuona weboka kutengeserana.
4. DML - anonyengera humboo yapihwa. Basa raro ari kubvumira inodzidzisa kutama zvakasiyana siyana mashoko kubva Database kana kukonzera izvozvo.

The Mhando neropafadzo kuripo pamusoro Server ichi

Under ropafadzo unoreva avo zviito zvinogona kuita mumwe kana mumwe anoishandisa maererano hweHIV. Dzika, Chokwadi, ndizvo zvinoitika Login. Chokwadi, nokufamba kwenguva ropafadzo inozviisa kuchinja. Old zvichabviswa dzadzimwa uye vatsva vakawedzera. Muna nhasi, vose vaya vanopfuura SQL Server makosi "nokuda dummies", ziva kuti pane mhando dzakawanda akabvumira mabasa:

1. Chinhu mhando - inodzidzisa anobvumirwa kuita chero murayiro chete pachinhu imwe chinhu chiri Database. Panguva iyoyo yokuti dzakasiyana zvinhu vari ropafadzo yakasiyana. Ivo kuda kwete chete kune imwe User, asiwo kune tafura. Kana munhu ari kushandisa mano avo, I akasika tafura, zvino runoonekwa kuti wayo. Saka, muna ake kana kodzero kugadza ropafadzo itsva vamwe vanoshandisa chokuita mashoko mariri.
2. System mhando - anonzi mashoko dzouridzi. Vatengi vanopiwa ropafadzo dzakadaro, anogona kuumba siyana zvinhu zviri Database.

Nhoroondo SQL

mutauro uyu akasikwa IBM muna 1970, kutsvakurudza murabhoritari. Kunyange zvazvo zita rake raiva siyanei (rakazotevera), asi pashure pemakore mashomanana kushandiswa, izvozvo zvakachinja, achidzikisa wedzeredzei. Pasinei neizvi, kunyange nhasi, vazhinji rinozivikanwa Nyanzvi dzakawanda mumunda mapurogiramu zvichiri kureva zita tsaru. SQL akasikwa aine chinangwa chimwe chete - kugadzira mumwe mutauro kuti hwaizova nyore kuti zvayaigona pasina zvinetso kudzidza kunyange nyore Internet vanozvishandisa. An dzinonakidza ndechokuti nepo SQL akanga asiri oga mutauro kwakadaro. In California, rimwe boka nyanzvi kwakasimbiswa yakafanana Ingres, asi haana kuchapararira. Kusvikira 1980, paiva zvakasiyana vanoverengeka SQL, izvo bedzi pamwero yakasiyana nepedyo. Kudzivirira kuvhiringidzika, muna 1983, mureza musiyano wezvinyorwa wakasikwa, inova nevakawanda nhasi. SQL makosi "nokuti Dummies" muzive zvakawanda pamusoro basa uye zvakazara kuongorora kuti kwemavhiki mashoma.