如何判断SQL Server 2008中创建约束的方法是什么？

ALTER TABLE table_name
ADD CONSTRAINT constraint_name PRIMARY KEY (column_name1, column_name2, ...);

ALTER TABLE table_name
ADD CONSTRAINT constraint_name UNIQUE (column_name1, column_name2, ...);

ALTER TABLE table_name
ADD CONSTRAINT constraint_name FOREIGN KEY (column_name1, column_name2, ...)
REFERENCES parent_table_name(parent_column_name1, parent_column_name2, ...);

ALTER TABLE table_name
ADD CONSTRAINT constraint_name CHECK (column_name1 > 0 AND column_name2 < 100);

ALTER TABLE table_name
ADD CONSTRAINT constraint_name DEFAULT 'default_value' FOR column_name;