Ka kohoʻana i kaʻikepili i loko o nā kiki ma SQL

Ke hoʻokomo nei i ka paukū WHERE a me keʻano o ka'ōlelo

ʻO ka Language Query Structured (SQL) ka mea hoʻohana i nā mea hoʻohana pūnaewele me ka hiki ke hana i nā hulina i hoʻopilipiliʻia e wehe i kaʻikepili mai nāʻikepili. Ma kekahiʻatikala mua, uaʻimi mākou i ka laweʻana i nāʻike mai kahi pūnaewele e hoʻohana ana i nā hulina SELELE SQL . E hoʻonui ma luna o ia kūkākūkā a me ka huliʻana i kahi e hiki ai iāʻoe ke hana i nā nīnau maʻamau e kiʻihoʻi i nāʻikepili i pili i nā kūlana kūikawā.

E noʻonoʻo kākou i kahi hiʻohiʻona e pili ana i kaʻikepili no Northwind database i hoʻohana pinepineʻia, kahi pinepineʻana me nā hua waihonaʻikepili me he kumu aʻo.

Eia kahi hapa o ka papahana Hua'ōlelo o ka database:

Kāleʻa Hua

ProductID	Inoa mea kūʻai	SupplierID	NuiPerUnit	UnitPrice	UnitsInStock
1	Chai	1	10 pahu x 20 mau peke	18.00	39
2	Huli	1	24 - 12 oz mau'ōmole	19.00	17
3	ʻO ka sygne Aniseed	1	12 - 550 ml mau omole	10.00	13
4	ʻO Chef Anton's Cajun Seasoning	2	48 - 6 'ai kek	22.00	53
5	ʻO Chef Anton's Gumbo Mix	2	36 pahu	21.35	0
6	Kākoʻo nuiʻo Grandma's Boysenberry	3	12 - 8 oz	25.00	120
7	ʻOʻAnakala Bobʻo Organic Dried Pears	3	12 - 1 lb pkgs.	30.00	15

Nā Kūlana Kū'ē Kūikawā

ʻO nā kumu mua a mākou e kau ai ma kā mākou hulina e komo i nāʻano palena palena. Hiki iā mākou ke hōʻike i kēia mau mea ma ka mahele WHAI o ka hulina SELECT, ma ka hoʻohanaʻana i nā'ōlelo pilikino i kūkuluʻia me nā meaʻoihana maʻamau, e like me <,>,> =, a <=.

ʻO ka mea mua, e ho'āʻo i kahi hulina maʻamau e hiki ai iā mākou ke unuhi i kahi papa inoa o nā huahana i loko o ka waihonaʻikepili i loaʻa kahi UnitPrice o 20.00:

SELECT ProductName, UnitPrice MAI nā huahana WHERE UnitPrice> 20.00

Hanaʻia ka papa inoa o nā huaʻehā, e like me ia i hōʻikeʻia i lalo nei:

ProductName UnitPrice ---------------- Keʻenaʻo Anton's Gumbo Mix 21.35 Keahiʻo Anton's Cajun Keahi 22.00 Hōʻikeʻanaʻo Grandma's Boysenberry 25.00 Uncle Bob's Organic Dried Pears 30.00

Hiki iā mākou ke hoʻohana i ka paukū WHERE me nā koina string. ʻO kēia helu maʻamau i nā helu i nā helu, me A e pili ana i ka helu 1 a me Z e kū ana i ka pono 26. Eia kekahi, hiki iā mākou ke hōʻike i nā huahana me nā inoa e hoʻomaka ana me U, V, W, X, Y, aiʻole Z me kēia nīnau:

Nā huahana SELEM MAI nā huahana WHERE ProductName> = 'T'

Ke hua nei i ka hopena:

ProductName -------ʻOʻAnakala Bob's Organic Dried Pears

Hōʻikeʻia nā Range me ka hoʻohanaʻana i Boundaries

ʻO ka wahi o ka WHAI kahi eʻae ai iā mākou e hoʻokō i kahi kūlana kūpono ma kahi waiwai ma ka hoʻohanaʻana i nā kumuhana he nui. Eia kekahi laʻana, inā makemake mākou e lawe i kā mākou hulina ma luna a palena i nā hualoaʻa i nā huahana me nā kumukūʻai ma waena o 1500 a 20.00, hiki iā mākou ke hoʻohana i kēia nīnau:

SELECT ProductName, UnitPrice MAI nā huahana WHERE UnitPrice> 15.00 a me UnitPrice <20.00

Hōʻike kēia i ka hopena i hōʻikeʻia i lalo nei:

ProductName UnitPrice ---------------- Chai 18.00 Chang 19.00

Hōʻike i nā pae me BETWEEN

Hoʻokumu pūʻiaʻo SQL i kahi pokiki BETWE syntax e ho'ēmi ana i ka helu o nā kūlana e pono ai mākou e hoʻokomo a hana i ka hulina iʻoi aku ka loli. Eia kekahi laʻana, ma kahi o ka hoʻohanaʻana i nā mea HIEREʻelua ma luna nei, hiki iā mākou ke hōʻike i kaʻili like hoʻokahi ma:

SELECT ProductName, UnitPrice MAI nā huahana WHERE UnitPrice MAI 1500 a me 20.00

E like me ko mākou mauʻanoʻokoʻaʻano, BETWEEN ke hana me nā koina string. Inā makemake mākou e hoʻopuka i kahi papa inoa o nā'āina a pau e hoʻomaka ana me V, W, aiʻole X, hiki iā mākou ke hoʻohana i ka hulina:

Nā huahana SELETAI MAI nā huahana WHERE MANNAMI I waena o "A" a me "D"

Ke hua nei i ka hopena:

ProductName ------- Aniseed Syrup Chai Chang Chef Kekuhi Kanahele Kekuhi Kanahele Kekuhi Anton Ke Cajun Seasoning

ʻO KA'ĀKAI KA wahi kahi mana o ka'ōlelo SQL e hiki ai iāʻoe ke hoʻonele i nā hopena i nā kālā e hāʻule ana i loko o nā papa i'ōleloʻia. He mea maʻalahi ke hoʻohanaʻia e kōkua i kaʻikeʻana i nāʻoihanaʻoihana a pono e lilo i māhele o kēlā me kēia mea hana waiwai o nā meaʻikepili.

He kōkua mau i ka hoʻohuiʻana i nā māhele likeʻole i loko o kahi hana mālamaʻia e hiki ai i ka poʻe me kaʻikeʻole o SQL.