在SQLServer数据库中，如果查询数据库中是否存在指定名称的索引或者外键约束等，经常会用到object_id('name','type')方法，
语法：object_id('objectname')或object('objectname','type')
作用：该函数会返回指定对象的ID值，可以在sysobjects表中进行验证。
type如下：
AF = Aggregate function (CLR)
C = CHECK constraint
D = DEFAULT (constraint or stand-alone)
F = FOREIGN KEY constraint
FN = SQL scalar function
FS = Assembly (CLR) scalar-function
FT = Assembly (CLR) table-valued function
IF = SQL inline table-valued function
IT = Internal table
P = SQL Stored Procedure
PC = Assembly (CLR) stored-procedure
PG = Plan guide
PK = PRIMARY KEY constraint
R = Rule (old-style, stand-alone)
RF = Replication-filter-procedure
S = System base table
SN = Synonym
SQ = Service queue
TA = Assembly (CLR) DML trigger
TF = SQL table-valued-function
TR = SQL DML trigger
U = Table (user-defined)
UQ = UNIQUE constraint
V = View
X = Extended stored procedure
操作看一下；