L-ewwel SELECT tiegħek f'Kotomarket
What you'll learn
- tikteb u tħaddem l-ewwel query tiegħek fil-forma
SELECT * FROM products LIMIT 5 - tikkontrolla d-daqs tar-riżultat billi tibdel in-numru ta' ringieli f'
LIMIT - tispjega għaliex
SELECThu sikur: jaqra d-data biss u ma jbiddel xejn fil-bażi
L-aktar query importanti
QUERY jiftaħlek il-konsol tal-arkivju — tieqa lewn l-ambra fid-dlam tal-kompartiment. Warajha, il-bażi tad-data ta' Kotomarket tinsab siekta: xerrejja, prodotti, ordnijiet u avvenimenti tal-imġiba, iffriżati mill-2024. Il-ħjiel minn tmiem id- kien ċar: ibda b'SELECT.
Il-biċċa l-kbira tax-xogħol bis-SQL tassew tibda b'azzjoni sempliċi: taqra d-data. Għal dan jintuża l-kmand SELECT — mistoqsija li biha l-bażi twieġeb bid-data: «urini x'għandek».
Nibdew mill-vetrina u nagħtu ħarsa lejn it-tabella products. Il-query t'hawn taħt titlob: «agħtini l-kolonni kollha (*) mit-tabella products, imma mhux aktar minn 5 ringieli». Hawn LIMIT n huwa limitu: jgħid lill-bażi biex tirritorna mhux aktar minn n ringieli (aktar 'il quddiem — flimkien mal-issortjar — nispjegawh fid-dettall fil-Kapitlu 2). Agħfas Ħaddem — u l-ewwel ringieli tal-vetrina, wara rqad ta' 160 sena, jerġgħu jieħdu l-ħajja fuq il-pannell olografiku. Imbagħad ibdel 5 għal 10 — tara mill-ewwel kif tikkontrolla kemm jirritorna r-riżultat.
QUERY: Agħfas bla biża'.
SELECTjaqra biss — b'query ta' qari ma tħassarx l-arkivju. Iċċekkjajt. Ħafna drabi.
SELECT iqajjem il-vetrina: ħames ringieli minn products jitilgħu mid-dlam fuq il-pannell olografiku.The single most important query
QUERY unfolds the archive console in front of you — an amber window in the darkness of the bay. Behind it the "Kotomarket" database sits in silence: buyers, products, orders and behavioral events, frozen since 2024. The hint at the end of the was clear: start with SELECT.
Most work with SQL really does begin with one simple act: read the data. That’s what the SELECT command is for — a question the database answers with data: "show me what you’ve got."
Let’s start with the storefront and peek into the products table. The query below asks: "return every column (*) from the products table, but no more than 5 rows." Here LIMIT n is the limiter: it tells the database to return at most n rows (looking ahead — we’ll dig into it properly, together with sorting, in Chapter 2). Hit Run, and the first rows of the storefront, asleep for 160 years, will come alive on the holopanel. Then change 5 to 10 — and you’ll see right away how to control how much the result returns.
QUERY: Go ahead, hit it.
SELECTonly reads — you can’t spoil the archive with a read query. I’ve tested that. Many times over.
| id | name | category | price | stock |
|---|---|---|---|---|
| 1 | Беспроводные наушники | Электроника | 5990.00 | 120 |
| 2 | Смарт-часы | Электроника | 8990.00 | 60 |
| 3 | Портативная колонка | Электроника | 3490.00 | 90 |
| 4 | Веб-камера HD | Электроника | 2790.00 | 45 |
| 5 | Механическая клавиатура | Электроника | 4590.00 | 70 |