help in solving a problem in sql server
I have aquestions from you. Does SQL server have any features so we can limit a field to fill with just specific values? For example assume that you have a field named "Name" then we want SQL just let us to fill this field with the following values: "Bella", "Jack", "Rose". is 开发者_如何学JAVAthere any featues to do it? please guide me. thanks
You can use a CHECK constraint:
ALTER TABLE dbo.YOUR_TABLE
ADD CONSTRAINT chk_name CHECK (name IN ('Rose', 'Bella', 'Jack'));
...but you might want to use a separate table & foreign key if you need to add identical CHECK constraints to numerous tables:
NAMES
- name_id (primary key)
- name
Foreign Key Constraint:
ALTER TABLE dbo.YOUR_TABLE
ADD CONSTRAINT fk_names FOREIGN KEY (name)
REFERENCES dbo.NAMES (name_id) ;
Use Check Constraint
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