没有动态SQL的动态搜索

Question

用户可以按名字，姓氏搜索客户，也可以选择进入城市。

只有当用户使用动态SQL输入一个没有w / o的SQL时，是否可以编写与CITY匹配的SQL？

CREATE PROCEDURE [dbo].[SearchCustomer]
@FirstName varchar(30) --REQUIRED
@LastName varchar(30)--REQUIRED
@City varchar(30)  --OPTIONAL
AS
SELECT * FROM CUSTOMER C WHERE
C.FirstName = @FirstName AND
C.LastName = @LastName AND
C.City = IsNull(@City, C.City) --This won't Work if CITY is optional in the database

Answer 1

尝试：

(@City is null OR C.City = @City) 

Answer 2

试试这个

COALESCE(C.City,"") = COALESCE(@City,C.City,"")

有关此功能的更多信息here

Answer 3

CREATE PROCEDURE [dbo].[SearchCustomer]
@FirstName varchar(30) --REQUIRED
@LastName varchar(30)--REQUIRED
@City varchar(30)  --OPTIONAL
AS

IF @City is NULL
BEGIN
SELECT * FROM CUSTOMER C WHERE
C.FirstName = @FirstName AND
C.LastName = @LastName
END
ELSE
BEGIN
SELECT * FROM CUSTOMER C WHERE
C.FirstName = @FirstName AND
C.LastName = @LastName AND
C.City = @City
END