SQL_ Conversion format Functions-cast () and CONVERT ()

An expression that explicitly converts an expression of one data type to another data type. CAST and CONVERT provide similar functionality.

Cast

SELECT CAST('12.5'  as int)--failed to convert varchar value ' 12.5 ' to data type int. SELECT CAST('12.5'  as decimal(5,3))--12.500SELECT CAST(12.5  as varchar)--12.5SELECT CAST('2016/07/01'  as datetime)--2016-07-01 00:00:00.000

Convert

The CONVERT () function is a general function that converts a date to a new data type.

The CONVERT () function can display date/time data in different formats.

Select Convert(varchar( -),GETDATE(), -)--2016-07-01 13:55:36Select Convert(varchar( -),GETDATE(),121)--2016-07-01 13:55:11.017Select Convert(varchar( -),GETDATE(),111)--2016/07/01Select CONVERT(VARCHAR( +),GETDATE())--1 1:43pm

Convert () function conversion format.

Select CONVERT(VARCHAR( +), A)-- ASelect CONVERT(int,' A')-- ASelect CONVERT(decimal,'12.647')-- -Select CONVERT(decimal(5,3),'12.647')--12.647Select CONVERT(datetime,'2016/07/01')--2016-07-01 00:00:00.000Select CONVERT(DateTime2,'2016/07/01')--2016-07-01 00:00:00.0000000

Reference:

https://technet.microsoft.com/zh-cn/library/ms187928 (sql.90). aspx

Http://www.w3school.com.cn/sql/func_convert.asp

SQL_ Conversion format Functions-cast () and CONVERT ()