在我的一个.NET应用软件中, 我试图用一个系统基底数据库调用一个存储程序, 根据我们的商业逻辑,我发送的一些值可能是无效的。
然而,如果我确实发送了无效值, 我就会得到一个“ 不支持的参数类型” 例外 。
有什么建议吗?
不将参数添加到命令中, s 就.NET而言, 该参数被视为无效 。
使用 DBNull. value 而不是 null , 当向数据库传递空值时使用 DBNull.value , 而不是 null 。
从"http://manuals.sybase.com/onlinebook/group-as/asg1250e/sqlug/@Generic_BookTextView/42965;pt=42726" rel="nofollow">Sybase : 您可以在创建程序语句中指定参数的默认值。如果用户不提供,此值可以是任何常数, 则用作该程序的参数的参数的参数的参数参数参数的参数参数参数参数参数的参数参数参数参数参数参数。 。
以下脚本声明一个有默认值的 SP, 然后通过执行 : 2, NULL, DEFAULT, 并且没有任何值。 您可以看到, 不指定参数的行为与通过 DEFAULT 相同, 并且它可能与通过 NULL 不同 。
这就是我指出的区别, 因为当您不声明 命令对象的参数时, 您得到的行为类型 :
CREATE PROCEDURE MySp(@p1 INT = 1)
AS BEGIN
SELECT @p1 AS [parameter_value];
END
GO
EXEC MySp 2; -- parameter value = 2
EXEC MySp NULL; -- parameter value = NULL
EXEC MySp DEFAULT; -- parameter value = 1
EXEC MySp; -- parameter value = 1
GO
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