2010年2月11日 · user_id in messages table is a fk field so it has to make clear which id is (user_id). a fully-self-explaining naming convention, in my opinion, could be: fk_[referencing table name]_[referencing field name]_[referenced table name]_[referenced field name] i.e.: `fk_messages_user_id_users_id`

2014年1月14日 · To do this without knowing the constraint's name and without inner joins, you can do: IF NOT EXISTS(SELECT NULL FROM INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE WHERE [TABLE_NAME] = 'Products' AND [COLUMN_NAME] = 'BrandID') BEGIN ALTER TABLE Products ADD FOREIGN KEY (BrandID) REFERENCES Brands(ID) END

2009年5月29日 · select fk_table = fk.table_name, fk_column = cu.column_name, pk_table = pk.table_name, pk_column = pt.column_name, constraint_name = c.constraint_name from information_schema.referential_constraints c inner join information_schema.table_constraints fk on c.constraint_name = fk.constraint_name inner join information_schema.table_constraints pk ...

Practically, it depends on how many tables have the FK definitions included. If someone bothered to carefully define all FK references -- and the SELECT statements stick to these rules -- you can query them. However, since a SELECT statement can join on anything, there's no guarantee that you have all FK's unless you also have all SELECT ...

2016年9月21日 · sp_rename 'HumanResources.FK_Employee_Person_BusinessEntityID', 'FK_EmployeeID'; will rename FK_Employee_Person_BusinessEntityID found in the HumanResources schema to FK_EmployeeID. If the schema is missing, SQL Server looks for objects in the user's default schema, which is often the dbo schema. If the FK is created in a different schema, you ...

2010年6月1日 · @Kangkan creating FK have nothing to do with performance FK != Indexes. There are DBMS automatic creates a index in the FK creation but most don't. Joins don't need FK please refer to excellent Daniel answer. Maybe OP is confused by ORM frameworks –

2013年8月26日 · Consider the case of a Customer table with a SSN column (and a dumb primary key), and a Claim table that also contains a SSN column (populated by business logic from the Customer data, but no FK exists). The design is flawed, but has been in use for several years, and three different applications have been built on the schema.

2009年1月27日 · IF (OBJECT_ID('dbo.FK_ConstraintName', 'F') IS NOT NULL) BEGIN ALTER TABLE dbo.TableName DROP CONSTRAINT FK_ConstraintName END If you need to drop another type of constraint, these are the applicable codes to pass into the OBJECT_ID() function in the second parameter position:

However, it makes a lot of sense to index all the columns that are part of any foreign key relationship. An FK-relationship will often need to look up a relating table and extract certain rows based on a single value or a range of values. So it makes good sense to index any columns involved in an FK, but an FK per se is not an index.

YES, a FK can speed up SELECT but slow down INSERT/UPDATE/DELETE. SQL Server uses all constraints (FK included) to build better execution plans for SELECTs. For instance, if you run a query with WHERE Column1 = X and X does not fit the constraint, the server won't even bother evaluating the condition.