Computed Column Operand type clash on Date Column When Checking For Null
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16-02-2021 - |
문제
This error is generated when trying to create a table with a computed column from a Date
field.
Operand type clash: int is incompatible with date
If I comment out the computed column it works.
[DateInActive][Date] NULL, -- Date origination
[IsValid] AS (IsNull(DateInActive, 1)) -- Failure here
The thought on IsValid
is to simply return a bit
of on|off for this field to signify that no in-active date has been reported and if so, it is valid.
The column will ultimately be passed on to JSON in a For JSON
output as a is-a
field for usage outside SQL.
Full SQL
CREATE TABLE [history].[PhoneBook](
[PhoneBookId] [int] IDENTITY(1,1) NOT NULL,
[PersonId] [int] NOT NULL,
[PhoneId] [int] NOT NULL,
[DateActive][Date] NOT NULL,
[DateInActive][Date] NULL,
[IsValid] AS (IsNull(DateInActive, 1))
CONSTRAINT [PK_PhoneBook_1] PRIMARY KEY CLUSTERED
(
[PersonId] ASC,
[PhoneId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
해결책
According to the ISNULL
documentation the returned data type is the same type as the check expression, which is data type date
in this case. The ISNULL
expression fails because the integer literal 1 cannot be implicitly converted to date.
To return a bit indicating whether or not the date column is NULL
, you could instead use a CASE expression:
CREATE TABLE [history].[PhoneBook](
[PhoneBookId] [int] IDENTITY(1,1) NOT NULL,
[PersonId] [int] NOT NULL,
[PhoneId] [int] NOT NULL,
[DateActive][Date] NOT NULL,
[DateInActive][Date] NULL,
[IsValid] AS CASE WHEN DateInActive IS NULL THEN CAST(0 AS BIT) ELSE CAST(1 AS bit) END
CONSTRAINT [PK_PhoneBook_1] PRIMARY KEY CLUSTERED
(
[PersonId] ASC,
[PhoneId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]