SQL SERVER中强制类型转换cast和convert的区别
在SQL SERVER中,cast和convert函数都可用于类型转换,其功能是相同的,
只是语法不同.
cast一般更容易使用,convert的优点是可以格式化日期和数值.
1 select CAST('123' as int) -- 123 2 select CONVERT(int, '123') -- 123 3 4 select CAST(123.4 as int) -- 123 5 select CONVERT(int, 123.4) -- 123 6 7 select CAST('123.4' as int) 8 select CONVERT(int, '123.4') 9 -- Conversion failed when converting the varchar value '123.4' to data type int. 10 11 select CAST('123.4' as decimal) -- 123 12 select CONVERT(decimal, '123.4') -- 123 13 14 15 select CAST('123.4' as decimal(9,2)) -- 123.40 16 select CONVERT(decimal(9,2), '123.4') -- 123.40 17 18 19 20 declare @Num money 21 set @Num = 1234.56 22 select CONVERT(varchar(20), @Num, 0) -- 1234.56 23 select CONVERT(varchar(20), @Num, 1) -- 1,234.56 24 select CONVERT(varchar(20), @Num, 2) -- 1234.5600
