Imininingwane 
 
 
 
 Usuku, isikhathi & Timestamp I-Integer, i-Float neBit I-Enums and Sets (I-This One) Ukuhlolwa Okuzenzakalelayo, le nqaku linikezela i-serie yami ye-MySQL data types. Ngaphezu kwalokho, ngifaka i-numeric types kanye ne-date/time types. Le nqaku lihlanganisa ku- Waze I-types, ama-data types ezizodwa ezisetshenziselwa i-lists ezincinane zebhizinisi futhi zibonisa izinhlamvu kakhulu, kodwa futhi kungase zibonise imibuzo uma asuswe ngokucacileyo. Ngizokufunda kuqala ukuthi kukhona, bese ukunikeza izibonelo zokungcoba ezivamile futhi indlela yokuvimbela. SET ENUM Yini i-ENUM ne-SET types? ENUM 
 
 
 
 
 I-string object okuyinto ingatholakala inani elilodwa esithathwe kusuka ku-predefined list. Isibonelo isicelo isibonelo: izinga lomsebenzisi ('ngokusho', 'ukudluliselwa', 'ukudluliselwa'). I-internally stored as a integer index (1-based) Ukusekelwa ku-65,535 elements (njenge-SMALLINT). SET 
 
 
 
 
 Umbala we-string okuyinto ungathola noma iyiphi imibala ye-value kusuka ku-lists e-predefined. Isibonelo isicelo: izinqubo abasebenzisi ('ukudala', 'bheka', 'ukushicilela'). Izixhobo ze-bitmap ye-internal (i-bit ye-bit ifakwe ukuba i-value iyatholakala). Ukusekelwa ku-64 izinto (njenge-BIT(64)). Syntax kanye nezibonelo Ngiyazi i-example table for orders with status field that used Uhlobo Ukucacisa Izimo ze-Orders Available: ENUM CREATE TABLE orders (
id INT AUTO_INCREMENT PRIMARY KEY,
status ENUM('pending','paid','shipped','cancelled') NOT NULL DEFAULT 'pending'
); Ukuze ubeke amamehlo amabili ku-table: INSERT INTO orders () VALUES ();
INSERT INTO orders (status) VALUES ('paid'); Ukubonisa zonke izilimi nge ukwakhiwa kwezinombolo ezengeziwe ze-state field: SELECT id, status, status+0 FROM orders;
+----+---------+----------+
| id | status  | status+0 |
+----+---------+----------+
|  1 | pending |        1 |
|  2 | paid    |        2 |
+----+---------+----------+
2 rows in set (0.000 sec) Ngiya ku-example table isikhunta : SET CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
permissions SET('read','write','delete') NOT NULL
); Ukukhishwa kwe-user nge-permissions eziningana: INSERT INTO abasebenzisi (umthombo) VALUES ('ukubala, ukudala'); Izimpahla ezivamile futhi indlela yokuvimbela Okwakheka, Ngingathanda ukuthi uma usebenzisa i-versions ezindala kakhulu ye-MySQL noma izakhiwo ezinguqile kakhulu, ungathanda ama-errors ezihlangene nezibalo ezivela ku-field definition. Ngokuvamile, izinga eluhlaza lithunywe ku-field. Kodwa ngithanda ukuthi ungasebenzisa izinguqulo ezinguqile ze-MySQL. Ngithanda futhi ukuba ufunde lezi zimpahla zezinhlobonhlobo ze-field futhi akufanele ukugcina ezingaphezu kuka-64 iziqu ze-set. Ngakho-ke, ingxaki elikhulu etholakalayo kubandakanya ukuguqulwa kwezinhlelo zamasiko. Qinisekisa ukuthi umuntu ukongeza ingxenye entsha ekubeni Ukulinganiswa okuqukethwe: ENUM CREATE TABLE orders (
id INT AUTO_INCREMENT PRIMARY KEY,
status ENUM('pending','paid','shipped') NOT NULL DEFAULT 'pending'
);
INSERT INTO orders (status) VALUES ('paid');
SELECT id, status, status+0 FROM orders;
+----+---------+----------+
| id | status  | status+0 |
+----+---------+----------+
|  1 | paid    |        2 |
+----+---------+----------+
1 rows in set (0.000 sec)
ALTER TABLE orders MODIFY status ENUM('pending','accepted','paid','shipped') NOT NULL DEFAULT 'pending'; Ukulungiselela Imininingwane izindlu njengama-integrals ngamazwe, lokhu kungcono ukuthi nathi: ENUM I-SELECT id, i-status, i-status+0 FROM izicelo; +----+----------+----------+
| id | status   | status+0 |
+----+----------+----------+
|  1 | accepted |        2 |
+----+----------+----------+
1 rows in set (0.000 sec) OOOPS! Ufuna ukunakekelwa ukuthi ukuguqulwa noma ukubeka umugqa omtsha noma lapho, kodwa ekupheleni ukuguqulwa ukucubungula i-index, okuholela idatha ezingenalutho. Yingxenye yesibili ngithanda ukubonisa ukuthi ngenkathi i-MySQL isitoreji i-enums kanye ne-sets njenge- integers, i-mySQL isitoreji futhi i-compares njenge-strings e-collated lapho ukhethe. Lokhu kungase kuthatha izivakashi abanamakhasimende abanamakhasimende. Ukuphakama Waze kungenziwa izixhobo ezinzima zokunciphisa amazinga ngqo ku-schema yakho. Kodwa nge-comfort yayo zihlanganisa ukubheka, imizuzu, kanye nokumiswa okucindezeleka. Ngokuvumelana nenkqubo yayo nokulandela izindlela ezinhle, ungakwazi ukuvikela amazinga amaningi ezivamile futhi ukugcina idatha yakho ngokuhambisana. ENUM SET Qhagamshelana nabanye amaphepha kulesi sethu okuhlola ezinye izinhlobo ze-MySQL data futhi indlela yokusebenzisa kwabo ngempumelelo.

This story contains new, firsthand information uncovered by the writer.

Lo msindo ukhiqizwa ngolimi lokuqala lwendaba!

Ukuhamba nge-MySQL Data Types: Sets and Enums

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