EXISTS
EXISTS
EXISTS buyrug‘i quyi so‘rovda biron bir yozuv mavjudligini tekshiradi,
va agar quyi so‘rov bir yoki bir nechta yozuvlarni qaytarsa, true qiymatini qaytaradi.
Quyidagi SQL mahsulot narxi 20 dan past bo‘lgan yetkazib beruvchilarni sanab o‘tadi:
Misol
SELECT SupplierName
FROM Suppliers
WHERE EXISTS (SELECT ProductName FROM
Products WHERE SupplierId = Suppliers.supplierId AND Price < 20);
O‘zingiz sinab ko‘ring »
Quyidagi SQLda mahsulot narxi 22 ga teng bo‘lgan yetkazib beruvchilar ro‘yxati keltirilgan:
Misol
SELECT SupplierName
FROM Suppliers
WHERE EXISTS (SELECT ProductName FROM
Products WHERE SupplierId = Suppliers.supplierId AND Price = 22);
O‘zingiz sinab ko‘ring »
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