[英]Can a foreign key in one table be non unique key attribute of the composite primary key of the second table?
這是表1 :
CREATE TABLE "table1" (
"date" TEXT NOT NULL,
"dispenser" TEXT NOT NULL,
"start_reading" REAL NOT NULL,
"end_reading" REAL,
"fuel_sold" REAL,
"amnt_earned" REAL,
"profit" REAL,
PRIMARY KEY("date","dispenser"),
);
這是表2 :
CREATE TABLE "discounts" (
"id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
"date" TEXT,
"name" TEXT,
"discount" REAL,
FOREIGN KEY("date") REFERENCES "daily_reports"("date")
);
當我嘗試在table2中插入數據時,它給出了外鍵約束錯誤。
Insert into discounts(date,name,discount) values(@date,@name,@amount)
不。
顧名思義,“外鍵”是另一個表的鍵。 根據定義,鍵在外表上是唯一的。
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