Indlela ukubhala SQL-imibuzo - Imizekelo ezineenkcukacha

Ngamnye wethu ujamelene rhoqo kwaye usebenzisa ezininzi zolwazi. Xa ukhetha le dilesi ye-imeyile, sisebenza kunye ledatha. database usebenzisa iinkonzo khangela, iibhanki kugcino lwe data zabathengi, njl

Kodwa nakuba ukusebenzisa njalo weenkcukacha, nkqu iinkqubo ezininzi zecomputer Ezikhululekilyo lot of "amabala amhlophe" ngenxa utoliko olwahlukileyo nemiqathango efanayo. Siya kunika inkcazo emfutshane amagama eziphambili zedata ze SQL ingqalelo. Ziyinyaniso

Database - ifayili okanye isethi iifayile ukugcina izakhiwo data odolwa kwaye ubudlelwane babo. Amaxesha amaninzi, database kuthiwa inkqubo yolawulo ledatha (DBMS). Database - yinto nje yokugcina ulwazi ngendlela ethile yaye ukusebenza kunye zolwazi ezahlukeneyo.

Uluhlu - cinga nefowulda apho amaxwebhu zigcinwa, amaqela ngaqela ngokungqinelana ezithile parameters, ezifana uluhlu lwe-odolo nyanga iphelileyo. Olu luhlu kwi computer ledatha. A itheyibhile eyahlukileyo inayo igama layo eyahlukileyo.

Uhlobo data - nohlobo lolwazi ukuba igcinwe njengomhalthi owodwa okanye emgceni. Kunokuba inani okanye itekisi ukulungiswa okungqalileyo.

Nekholam nakuluhlu - sonke sasebenza kunye spreadsheets, nazo makabekho kwigumbi lwemiqolo nemihlathi. Nayiphi database zonxulumelwano isebenza kunye neetafile ngendlela efanayo. Strings maxa wambi ebizwa ngokuba iingxelo.

A iqhosha - kumqolo ngamnye abe omnye okanye ngaphezulu imihlathi ukuba yesazisi yaso eyodwa. Akukho iqhosha kunzima kakhulu ukuhlaziya, ulungise uze ususe imiqolo efanelekileyo.

Yintoni SQL?

Ingxaki yokwakhiwa kolwimi SQL (IsiNgesi yokwakhiwa kolwimi -. Ingxaki yokwakhiwa kolwimi) yaye ilungiselelwe kuphela ukusebenza kunye oovimba yaye sithetha nje umgangatho wawo onke zolwazi ezithandwayo. Le lwesivakalisi ulwimi libunjwa inani elincinane kwabasebenzisi lula ukufunda. Kodwa nakuba lula ngathi, ivumela indalo imibuzo SQL ukuba imisebenzi ezimbaxa kunye ledatha nawuphi na ubukhulu.

Ukususela ngo-1992, kukho umgangatho ofanayo, ekuthiwa ANSI SQL. Icacisa lwesivakalisi ezingundoqo kunye nemisebenzi abaqhubi kunye kuxhaswa zonke iinkokheli DBMS emarikeni, ezifana Oracle i-Microsoft Kumncedisi we SQL le. Cinga zonke iinkalo ulwimi kwinqaku elifutshane akunakwenzeka, ngoko siza siqwalasele kuphela imibuzo esisiseko SQL. Imizekelo ibonisa ekunyaniseni iimpawu zolwimi:

• ekudaleni zolwazi neetafile;
• Ukukhetha data;
• Ukongeza entries;
• ukulungiswa kunye nokususwa ulwazi.

Types SQL Data

Zonke lemizuzwana kuchazo lwexesha itafile database ukugcina uhlobo data olufanayo. SQL data iindidi ziyafana nezinye uhlelo iilwimi.

uhlobo lwedatha	incazelo
INT	integers
REAL	Incopho amanani indawo
TEXT	Character umtya ubude bume
DATE	SQL umbuzo "umhla" ngeendlela ezahlukeneyo yeefomati
TIME	ixesha
char	imitya Yombhalo ubude esisigxina

Yakha iitafile iinkcukacha

Yenza iinkcukacha ezintsha, iitafile, kunye nezinye imibuzo kwi SQL Kukho iindlela ezimbini:

• iingxelo SQL ngokusebenzisa database console
• Ukusebenzisa interactive izixhobo Ulawulo, inxalenye womncedisi ledatha.

A Umqhubi iziko ledatha elitsha Dala DATABASE ; . Njengoko ubona, i lwesivakalisi kulula ngqo.

Iitheyibhile ngaphakathi kuvimba ukudala MASIDALE ULUHLU Inkcazo kunye parameters zilandelayo:

• igama letheyibhile
• amagama kunye neenkcukacha neentlobo columns

Ngokomzekelo, ukudala itafile yorhwebo kunye kwiikholam zilandelayo:

column	incazelo
commodity_id	ID imveliso
vendor_id	Umthengisi ID (abathengisi Key itheyibhile yangaphandle)
commodity_name	igama lemveliso
commodity_price	iindleko
commodity_desc	incazelo

Yenza itafile:

Dala ITHEYIBHILE yorhwebo

(Char commodity_id (15) NOT byte,

vendor_id Char (15) NOT byte,

commodity_name Char (254) byte,

commodity_price IDESIMALI (8,2) byte,

commodity_desc VARCHAR (1000) byte);

Le bhokisi iqulathe ezintlanu iikholam. Emva kokuba igama uhlobo lwemihlathi data wodwa ngeziphumlisi. Ixabiso umhlathi kuthathwa amaxabiso null (byte) okanye kufuneka ligcwaliswe (NOT byte), kwaye uzimisele ukwenza itafile.

kwisampulu yolwazi evela etafileni

data umqhubi yesampulu - imibuzo SQL ezininzi ezisetyenziswayo ngokuqhelekileyo. Ukuze ufumane inkcazelo engakumbi kufuneka ucacise ukuba sifuna ukuba ukhethe kusuka itafile. Ekuqaleni a alula Umzekelo:

commodity_name KHETHA FROM yorhwebo

Emva kokuba ingxelo KHETHA ukucacisa igama ikholam ukufumana ulwazi, kodwa ichaza itafile.

iziphumo umbuzo iya kuba yonke imiqolo itafile kunye neenqobo Commodity_name ngokokulandelelana leyo bangena database ngamanye ngaphandle yokuhlela. Ukulungisa iziphumo usebenzisa UMYALELO yomsebenzisi ozikhethelayo BY.

Ukukhalazela kwiinkalo ezininzi zibhale wodwa ngeziphumlisi njengoko mzekelo ulandelayo:

commodity_id KHETHA, commodity_name, commodity_price FROM yorhwebo

Kuyenzeka ukufumana ngenxa yexabiso yombuzo umtya zonke iikholam. Ukulungiselela le njongo, umqondiso "*":

* KHETHA FROM yorhwebo

• KHETHA ngaphezu ixhasa:
• data Uhlobo (UMYALELO BY statement)
• Ukhetho ngokungqinelana nemiqathango (APHO)
• igama ngokwamaqela (GROUP BY)

yongeza umgca

Ukongeza imiqolo ukuya kwitheyibhile usebenzisa iingxelo SQL mazwi INSERT. Ukudibanisa kungenziwa ngeendlela ezintathu:

• dibanisa ilayini entsha lonke;
• lomgca;
• umbuzo iziphumo.

Ukudibanisa umgca epheleleyo, kufuneka ukhankanye igama itafile kunye amaxabiso lwemihlathi (fields) yomgca entsha. Nanku umzekelo:

Faka IBE ZENTSULUNGEKO yorhwebo ( '106', '50', 'Coca-Cola', '1,68', 'Akukho Alcogol,)

Umzekelo ingeza imveliso entsha etafileni. Iimpawu zentsulungeko icaciswe emva amanani kwikholam nganye. Ukuba akukho ixabiso yabo umhlathi, kuyimfuneko ukuba ukhankanye byte. Ezi ntsika azele amaxabiso ngendlela elikhankanyiweyo xa kudalwa itafile.

Kwimeko ngokongeza inxalenye kuphela bomtya kufuneka ngokucacileyo ucacise igama umhlathi, njengoko ku Umzekelo:

INSERT IBE Commodity (commodity_id, vendor_id, commodity_name)

ZENTSULUNGEKO ( '106', '50', 'Coca-Cola', )

Siye sazisa kuphela identifier imveliso, umthengisi kunye negama layo, yaye ezinye yentsimi babeka bucala lilambatha.

Ukongeza iziphumo zombuzo

Ngokusisiseko, yofako kusetyenziswa ukongeza mkrozweni mnye, kodwa ingasetyenziswa ukwengeza iziphumo KHETHA ingxelo.

utshintsho data

Ukutshintsha nkcukacha kwimihlaba table ledatha kufuneka usebenzise i ingxelo UPDATE. Umsebenzisi ingasetyenziswa ngeendlela ezimbini:

• Updated yonke imiqolo kwindlela yemigca.
• Kuphela umgca ethile.

UHLAZIYO inezigaba ezintathu eziphambili:

• isithebe ofuna ukwenza utshintsho;
• amagama kunye nemilinganiselo zabo ezintsha;
• Iimeko ngokuba kumqolo yokukhetha utshintsho.

Xiya xikombiso lexi. Masithi imveliso kunye ID = 106 itshintshiwe ixabiso, ngoko eli umgca ukuze uhlaziye. Bhala la mazwi alandelayo:

UHLAZIYO Commodity SET commodity_price = '3.2' APHO commodity_id = ' 106'

Siye wabonisa igama itafile, kulo mzekelo, i yorhwebo, nto leyo iya kuhlaziywa, uze emva SET - ixabiso elitsha kwikholam ze bafumane into oyifunayo, ezicacisa ixabiso ID WHERE ezinqwenelekayo.

Ukutshintsha inani lwemihlathi emva SET uchonga ngababini eziliqela column-value, wodwa ngeziphumlisi. Bona umzekelo apho igama ixabiso impahla oluhlaziyiweyo:

UHLAZIYO ezityiwayo SET commodity_name = 'Fanta' , commodity_price = '3.2' APHO commodity_id = ' 106'

Ukucima ulwazi kwikholam, ungabeka ukuba null, ukuba ivumela isakhiwo itafile. Kumele kukhunjulwe ukuba ukuvuselelwa byte - lo "hayi" ixabiso, hayi zero okubhaliweyo okanye amanani. Susa incazelo intwana:

UHLAZIYO Commodity SET commodity_desc = byte APHO commodity_id = ' 106'

Isusa imiqolo

izicelo SQL ukucima imiqolo kwindlela yemigca iyenziwa operator Cima. Kukho iindlela ezimbini zokusebenzisa:

• Table lususiwe imiqolo ezithile;
• wasusa yonke imiqolo kwindlela yemigca.

UMZEKELO ukususa elinye umqolo kolu luhlu:

Sula Commodity APHO commodity_id = '106'

Emva sula Ikhankanya igama letheyibhile apho ukucima imiqolo. APHO umqhubi luquka imeko phantsi komgca iya kukhethelwa ukususwa. Kulo mzekelo sisusa imveliso kaloliwe nge ID = 106. PHI abonisa kubaluleke kakhulu kuba Kwathi le privedt yomsebenzisi ukususa yonke imiqolo kwindlela yemigca. Oku kusebenza ukutshintsha amaxabiso endle.

Ingxelo Cima ayicacisi amagama lomhlathi, kwaye meta-abalinganiswa. Lowo ususa ngokupheleleyo umgca kwaye ukucima njengomhalthi owodwa, yena akakwazi.

Ukusebenzisa SQL kwi Ufikelelo Microsoft

Microsoft Access uqobo kusetyenziswa ngothethwano ukudala spreadsheet, database, utshintsho zolawulo, uhlalutyo lwe data kwiziko ledatha yaye ukuze kuphunyezwe Access imibuzo SQL nge umbuzo interactive elula umakhi (Ingxaki yokwakhiwa Umyili), esebenzisa sokwakha yaye ngoko nangoko abulale iingxelo SQL nayiphi xaka.

Kwakhona inkxaso imo ukufikelela kumncedisi, apho Access ledatha ingasetyenziswa njengako SQL-zombuzo wenkunkuma ukuba nawuphi ODBC umthombo weenkcukacha. Olu phawu kwenza izicelo ukunxibelelana Access i- database nangayiphi na indlela.

izandiso SQL

Ngenxa imibuzo SQL abanalo zonke iimpawu ulwimi lokuprograma yeenkqubo ezifana kweziporo zikaloliwe, eyayizalwa, njl, abenzi DBMS ukuphuhlisa uguqulelo yabo SQL kunye ezinga eliphezulu. Okokuqala inkxaso iinkqubo agcinwe nakubanini standard iilwimi yenkqubo.

Ezizalana zixhaphakileyo yolwimi:

• Oracle Database - PL / SQL
• Interbase, Firebird - PSQL
• Umncedisi SQL Microsoft - Transact-SQL
• PostgreSQL - PL / pgSQL.

SQL Internet

database I SQL yam ukhululeka phantsi mvume ezamahala mvume GNU General Public. Kukho mvume yorhwebo bakwazi ukuphuhlisa iimodyuli siko. Njengenxalenye yale nxalenye ithandwayo abancedisi ukwakha Internet ezifana XAMPP, WAMP Nesibane, kwaye uphuhliso isicelo ledatha idumileyo kwi Internet.

It saphuhliswa yi-Sun Microsystems kwaye ngoku kuxhaswa ngomhla ka Oracle. Usekela database ubungakanani ukuya terabytes 64, i-SQL lwesivakalisi eqhelekileyo: 2003, i-phindana zolwazi kunye neenkonzo efini.