创建一个用户定义的函数.这将避免Fedor Hajdu mentioned与货币、小数等有关的问题:
CREATE FUNCTION dbo.TryConvertInt(@Value varchar(18))
RETURNS int
AS
BEGIN
SET @Value = REPLACE(@Value, ',', '')
IF ISNUMERIC(@Value + 'e0') = 0 RETURN NULL
IF ( CHARINDEX('.', @Value) > 0 AND CONVERT(bigint, PARSENAME(@Value, 1)) <> 0 ) RETURN NULL
DECLARE @I bigint =
CASE
WHEN CHARINDEX('.', @Value) > 0 THEN CONVERT(bigint, PARSENAME(@Value, 2))
ELSE CONVERT(bigint, @Value)
END
IF ABS(@I) > 2147483647 RETURN NULL
RETURN @I
END
GO
-- Testing
DECLARE @Test TABLE(Value nvarchar(50)) -- Result
INSERT INTO @Test SELECT '1234' -- 1234
INSERT INTO @Test SELECT '1,234' -- 1234
INSERT INTO @Test SELECT '1234.0' -- 1234
INSERT INTO @Test SELECT '-1234' -- -1234
INSERT INTO @Test SELECT '$1234' -- NULL
INSERT INTO @Test SELECT '1234e10' -- NULL
INSERT INTO @Test SELECT '1234 5678' -- NULL
INSERT INTO @Test SELECT '123-456' -- NULL
INSERT INTO @Test SELECT '1234.5' -- NULL
INSERT INTO @Test SELECT '123456789000000' -- NULL
INSERT INTO @Test SELECT 'N/A' -- NULL
SELECT Value, dbo.TryConvertInt(Value) FROM @Test
Reference:我在创建解决方案时广泛使用了this page.