在SQL中插入两个列的约束
大家好，我为数据库创建了此表，
CREATE TABLE IF NOT EXISTS compositions (
id INTEGER PRIMARY KEY AUTOINCREMENT,
id_product INTEGER REFERENCES products(id),
id_receipt INTEGER REFERENCES receipt(id),
quantity INTEGER NOT NULL,
price FLOAT NOT NULL,
id_user VARCHAR REFERENCES users(id),
CONSTRAINT CHK_price_quantity CHECK (price > 0 AND quantity > 0)
);
我想插入一个约束，对于给定的ID_receipt，ID_USER必须始终相同，但我不知道该如何实现。 有人可以帮助吗？
先感谢您。
Hi everyone I created this table for a database
CREATE TABLE IF NOT EXISTS compositions (
id INTEGER PRIMARY KEY AUTOINCREMENT,
id_product INTEGER REFERENCES products(id),
id_receipt INTEGER REFERENCES receipt(id),
quantity INTEGER NOT NULL,
price FLOAT NOT NULL,
id_user VARCHAR REFERENCES users(id),
CONSTRAINT CHK_price_quantity CHECK (price > 0 AND quantity > 0)
);
I would like to insert a constraint that, for a given id_receipt, the id_user must be always the same but I don't know how to implement it.
Could someone give a help?
Thank you in advance.
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对于此要求，列
id_user不应在表coptosings。中定义。
将其存储在表
Receipt中更有意义，由于每个id_receipt与1相关，只有1个id_user。这样，您将
id_receipt作为中的外键构图，通过此列，您可以从receip（例如id_user）获得（通过加入）所需的所有信息。For this requirement the column
id_usershould not be defined in the tablecompositions.It makes more sense to store it in the table
receipt, since eachid_receiptis related to 1 and only 1id_user.This way you have
id_receiptas a foreign key incompositionsand through this column you can get (by a join) all the info that you want fromreceipt, like theid_user.