sql-server - SQL Server 中外键是否自动建立索引？

Question

以下 SQL 语句会自动在 Table1.Table1Column 上创建索引，还是必须显式创建索引？

数据库引擎是SQL Server 2000

       CREATE TABLE [Table1] (
. . .
            CONSTRAINT [FK_Table1_Table2] FOREIGN KEY 
            (
                [Table1Column]
            ) REFERENCES [Table2] (
                [Table2ID]
            )

        )

Answer 1

SQL Server 不会自动在外键上创建索引。同样来自 MSDN:

A FOREIGN KEY constraint does not have to be linked only to a PRIMARY KEY constraint in another table; it can also be defined to reference the columns of a UNIQUE constraint in another table. A FOREIGN KEY constraint can contain null values; however, if any column of a composite FOREIGN KEY constraint contains null values, verification of all values that make up the FOREIGN KEY constraint is skipped. To make sure that all values of a composite FOREIGN KEY constraint are verified, specify NOT NULL on all the participating columns.