MySQL SELECT FROM
Jadvaldan tanlash
MySQL-dagi jadvaldan ma’lumotlarni tanlash uchun "SELECT" iborasidan foydalaning.
Misol
"Mijozlar" jadvalidagi barcha yozuvlarni tanlang va natija obyektini ko‘rsating:
let mysql = require('mysql');
let con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT * FROM customers", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});
Misolni ishga tushirish »
SELECT * barcha ustunlarni qaytaradi
Yuqoridagi kodni "demo_db_select.js" nomli faylga saqlang va faylni ishga tushiring:
"demo_db_select.js" ni ishga tushiring
C:\Users\Your Name>node demo_db_select.js
Bu sizga bu natijani beradi:
[
{ id: 1, name: 'John', address: 'Highway 71'},
{ id:
2, name: 'Peter', address: 'Lowstreet 4'},
{ id: 3, name: 'Amy',
address: 'Apple st 652'},
{ id: 4, name: 'Hannah', address:
'Mountain 21'},
{ id: 5, name: 'Michael', address: 'Valley 345'},
{ id: 6, name: 'Sandy', address: 'Ocean blvd 2'},
{ id: 7,
name: 'Betty', address: 'Green Grass 1'},
{ id: 8, name: 'Richard',
address: 'Sky st 331'},
{ id: 9, name: 'Susan', address: 'One way
98'},
{ id: 10, name: 'Vicky', address: 'Yellow Garden 2'},
{ id: 11, name: 'Ben', address: 'Park Lane 38'},
{ id: 12, name: 'William',
address: 'Central st 954'},
{ id: 13, name: 'Chuck', address:
'Main Road 989'},
{ id: 14, name: 'Viola', address: 'Sideway
1633'}
]
Ustunlarni tanlash
Jadvaldagi faqat ba’zi ustunlarni tanlash uchun ustun nomidan keyin "SELECT" iborasidan foydalaning.
Misol
"Mijozlar" jadvalidan ism va manzilni tanlang va qaytarish obyektini ko‘rsating:
let mysql = require('mysql');
let con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT name, address FROM customers", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});
Misolni ishga tushirish »
Yuqoridagi kodni "demo_db_select2.js" deb nomlangan faylga saqlang va faylni ishga tushiring:
"demo_db_select2.js" ni ishga tushiring
C:\Users\Your Name>node demo_db_select2.js
Bu sizga bu natijani beradi:
[
{ name: 'John', address: 'Highway 71'},
{ name: 'Peter', address: 'Lowstreet 4'},
{ name: 'Amy',
address: 'Apple st 652'},
{ name: 'Hannah', address:
'Mountain 21'},
{ name: 'Michael', address: 'Valley 345'},
{ name: 'Sandy', address: 'Ocean blvd 2'},
{
name: 'Betty', address: 'Green Grass 1'},
{ name: 'Richard',
address: 'Sky st 331'},
{ name: 'Susan', address: 'One way
98'},
{ name: 'Vicky', address: 'Yellow Garden 2'},
{ name: 'Ben', address: 'Park Lane 38'},
{ name: 'William',
address: 'Central st 954'},
{ name: 'Chuck', address:
'Main Road 989'},
{ name: 'Viola', address: 'Sideway
1633'}
]
Natija obyekti
Yuqoridagi misol natijasidan ko‘rinib turibdiki, natija obyekti an obyekt sifatida har bir qatorni o‘z ichiga olgan massiv.
Qaytish uchun, masalan. uchinchi yozuvning manzili, faqat uchinchi qatorga murojaat qiling obyekt manzili xususiyati:
Misol
Uchinchi yozuvning manzilini qaytaring:
console.log(result[2].address);
Qaysi natijani beradi:
Apple st 652
Maydonlar obyekti
callback qilish funksiyasining uchinchi parametri o‘z ichiga olgan massivdir natijadagi har bir maydon haqida ma’lumot.
Misol
“Mijozlar” jadvalidan barcha yozuvlarni tanlang va maydonlar obyektini ko‘rsating:
let mysql = require('mysql');
let con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT name, address FROM customers", function (err,
result, fields) {
if (err) throw err;
console.log(fields);
});
});
Misolni ishga tushirish »
Yuqoridagi kodni "demo_db_select_fields.js" deb nomlangan faylga saqlang va faylni ishga tushiring:
"demo_db_select_fields.js" ni ishga tushiring
C:\Users\Your Name>node demo_db_select_fields.js
Bu sizga bu natijani beradi:
[
{
catalog: 'def',
db:
'mydb',
table: 'customers',
orgTable: 'customers',
name: 'name',
orgName: 'name',
charsetNr: 33,
length: 765,
type: 253,
flags: 0,
decimals: 0,
default: undefined,
zeroFill: false,
protocol41: true
},
{
catalog: 'def',
db: 'mydb',
table: 'customers',
orgTable: 'customers',
name: 'address',
orgName: 'address',
charsetNr: 33,
length: 765,
type:
253,
flags: 0,
decimals: 0,
default: undefined,
zeroFill: false,
protocol41: true
}
]
Yuqoridagi misol natijasidan ko‘rinib turibdiki, maydonlar obyekti an obyekt sifatida har bir maydon haqidagi ma’lumotlarni o‘z ichiga olgan massiv.
Qaytish uchun, masalan. ikkinchi maydon nomi, faqat ikkinchi massiv elementining nom xususiyatiga murojaat qiling:
Misol
Ikkinchi maydon nomini qaytaring:
console.log(fields[1].name);
Qaysi natijani beradi:
address
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