SQL SERVER中強(qiáng)制類(lèi)型轉(zhuǎn)換cast和convert的區(qū)別詳解

select CAST('123' as int)  -- 123
select CONVERT(int, '123') -- 123

select CAST(123.4 as int)  -- 123
select CONVERT(int, 123.4) -- 123 

select CAST('123.4' as int)
select CONVERT(int, '123.4')
-- Conversion failed when converting the varchar value '123.4' to data type int.

select CAST('123.4' as decimal) -- 123
select CONVERT(decimal, '123.4') -- 123 


select CAST('123.4' as decimal(9,2)) -- 123.40
select CONVERT(decimal(9,2), '123.4') -- 123.40


declare @Num money
set @Num = 1234.56
select CONVERT(varchar(20), @Num, 0) -- 1234.56
select CONVERT(varchar(20), @Num, 1) -- 1,234.56
select CONVERT(varchar(20), @Num, 2) -- 1234.5600