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WHERE (SQL)

Chu Dian : huri-Bai Ke Shi Dian {uikipedeia(Wikipedia)}

WHEREJu ha, SQLniokeruYu Yue Yu no1tsudearu. de-taCao Zuo Yan Yu (DML) toGong niShi Yong shi, DMLgaCao Zuo suruXing woXian Ding suruYi Ge woChi tsu.

WHEREJu noZhi Ding haBi Xu dehanaiga, de-tawoCao Zuo suruMing Ling toYi Xu niShi Yong surukotodeDui Xiang woXian Ding surukotogadekiru.

Ju Ti De niha, SELECT, INSERT, UPDATE, DELETE noGe Ming Ling deCao Zuo Dui Xiang noXing woXian Ding surukotogadekiru[1].

Wen Fa

[Bian Ji ]

WHERE hade-taCao Zuo Yan Yu (DML) toGong niShi Yong sareru. Yi Ban De naGou Wen haYi Xia noyouninaru.

SQL-DMLMing Ling
FROM te-buruMing
WHERE Tiao Jian

WHERE noHou niJi Shu saretaTiao Jian gaZhen notoki DML noCao Zuo (Chou Chu *Xue Chu nado)noDui Xiang tonaru. Tiao Jian gaWei matahaBu Ming (NULL) notoki, Cao Zuo noDui Xiang tonaranai.

Ci nokueri-ha, mytable te-buruno mynumber ga100yoriDa kiimonowoChou Chu suru.

SELECT *
FROM mytable
WHERE mynumber > 100

Ci no DELETEWen ha, mytable te-buruno mynumber niZhi gaRu tsuteinaika, 100gaRu tsuteirumonowoXue Chu suru.

DELETE
FROM mytable
WHERE mynumber IS NULL OR mycol = 100

Tiao Jian Wen

[Bian Ji ]

Dan Chun naTiao Jian Wen ha, Yan Suan Zi no =, <>, >, >=, <, <=, IN, BETWEEN, LIKE, IS NULL or IS NOT NULL woShi Yong suru.

Tiao Jian Shi haBi Yao niYing zitekatsukodeWei mukotogadekiru. mata, Fu Shu noTiao Jian Wen wo AND ya OR deJie Sok surukotogadekiru. konoYou Xian Shun Wei woMing Shi surutamenimokatsukohaYou Yong dearu. katsukoganaiChang He , AND Yan Suan Zi ga OR Yan Suan Zi niYou Xian sareru.

Yi Xia noLi ha mytable te-buruniaru[mynumber ga100yoriDa kii] katsu[{aitemu} ga{hanma-} ] dearude-tawoXue Chu suru.

DELETE
FROM mytable
WHERE mynumber > 100 AND aitemu = 'hanma-'

IN ha, Zhi Hou niJi Shu shitade-taQun noZhong niYi Zhi suruZhi gaarukadoukawoPan Duan suru.

SELECT ename WHERE ename IN ('Zhi 1', 'Zhi 2', ...)

konoWen noChang He , ename gakatsukonoZhong noizurekatoYi Zhi surebaZhen tonaru. Li ebaZhi ga2tsunoChang He haYi Xia noWen toTong Deng ninaru.

SELECT ename WHERE ename='Zhi 1' OR ename='Zhi 2'

Hou Zhe noShu kiFang noChang He Fu Shu noLie woPan Ding niHan merukotogadekiruga IN dehaDan Yi noXiang Mu shikaDui Xiang nidekinai. Yi Fang , Hou Bu noJian Shu Duo iChang He ha IN woShi Yong shitaFang gaJian Jie niShu kukotogadekiru.

BETWEEN

[Bian Ji ]

BETWEEN ha, Zhi Ding saretaFan Wei Nei niZhi gaarukawoPan Duan suru.

SELECT ename WHERE ename BETWEEN 'Zhi 1' AND 'Zhi 2'

Yi Xia noLi haShou Ru ga[500000Yi Shang 1000000Yi Xia ] node-tawoChou Chu suru.

SELECT Shou Ru from emp WHERE Shou Ru BETWEEN 500000 AND 1000000

LIKE

[Bian Ji ]

LIKE haTiao Jian niHe uWen Zi Lie woJian Suo suru.

Mo Wei nowairudoka-do
Xia noLi ha 'S' deShi marusubetenoWen Zi Lie gaYi Zhi suru.
SELECT ename FROM emp WHERE ename LIKE 'S%';
Mou Tou nowairudoka-do
Xia noLi ha 'S' deZhong warusubetenoWen Zi Lie gaYi Zhi suru.
SELECT ename FROM emp WHERE ename LIKE '%S';
Fu Shu nowairudoka-do
Xia noLi ha 'S' gadokokaniHan marerusubetenoWen Zi Lie gaYi Zhi suru.
SELECT ename FROM emp WHERE ename LIKE '%S%';
1Wen Zi Fen nowairudoka-do
Xia noLi ha 'A' to 'E' noJian ni1Wen Zi dakeWen Zi gaCun Zai suruWen Zi Lie niYi Zhi suru.
SELECT ename FROM emp WHERE ename LIKE '%A_E%';
Wen Zi kurasu[2]
Xia noLi haZui Chu noWen Zi gaaruhuabetsutokaShu Zi ka '_' dearuWen Zi Lie niYi Zhi suru.
SELECT ename FROM emp WHERE ename LIKE '[a-zA-Z0-9_]%';

SQL woShi Yong suruChang He , LIKEYan Suan Zi haSuo Yin niyorupahuo-mansuwoWu Shi surukotowoRen Shi suruBi Yao gaaru. Ke Neng naraba '=' ya '<>' nadonoYan Suan Zi woShi Yong shitaFang gapahuo-mansugaii. mata, de-tabe-susohutoniyotsuteWen Zi noXi i(Da Wen Zi toXiao Wen Zi nado)gaWei ukotonimoZhu Yi shinaitoikenai.

Can Zhao

[Bian Ji ]
  1. ^ "SQL WHERE Clause - Things beginners must know". 2017Nian 10Yue 9Ri Yue Lan .
  2. ^ Microsoft TechnetRetrieved 21 November 2013.

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