SQL中的cast和convert的用法和区别

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