Converting date time format

Question

We have data in a Visit_Time column stored in 24Hrs date format as well as 12Hrs.

The data is inserted into a table from a different type of source like MobileApp and Web source etc.

Example:

Create table VisitorDetails
(
  Visit_Date Date,
  Visit_Time varchar(12)
)

VisitorDetails
----------------------------
Visit_Date      Visit_Time 
----------------------------
2020-01-01       01:00PM
2020-01-02       17:00
2020-01-03       04:00PM
2020-01-04       20:00
-----------------------------

How to convert Visit_Time Column either in 12 Hrs format or 24 Hrs formate?

Need Result like below

VisitorDetails     12Hrs                  24Hrs
----------------------------           --------------
Visit_Date      Visit_Time      (OR)     Visit_Time
----------------------------           --------------
2020-01-01       01:00PM                   13:00              
2020-01-02       05:00PM                   17:00              
2020-01-03       04:00PM                   16:00
2020-01-04       08:00PM                   20:00
-----------------------------          --------------

Answer 1

Please try below solution:

--24 Hour Format
SELECT  CONVERT(VARCHAR(5),CONVERT(DATETIME, '01:00PM', 0), 108) 
SELECT  CONVERT(VARCHAR(5),CONVERT(DATETIME, '17:00', 0), 108) 

--12 Hour Format
SELECT LTRIM(RIGHT(CONVERT(VARCHAR(20), CONVERT(DATETIME, '01:00PM', 0), 100), 7))
SELECT LTRIM(RIGHT(CONVERT(VARCHAR(20), CONVERT(DATETIME, '17:00', 0), 100), 7))

Answer 2

12 hour format

declare @t1 time
declare @t2 time
declare @t3 time

set @t1 = '14:40'
set @t2 = '17:00'
set @t3 = '01:00PM'

select CONVERT(varchar(15),@t1,100)
select CONVERT(varchar(15),@t2,100)
select CONVERT(varchar(15),@t3,100)

Answer 3

When fetching your rows you could do:

SELECT [Visit_Date], LEFT(PARSE([Visit_Time] AS time), 5)
FROM [VisitorDetails]

for a consistent time format. However, I would strongly recommend returning time values from the db and do the display modification in your app.

Answer 4

To Store 24 hrs format declare the Column data type as DATETIME Instead of Varchar(12)

DECLARE @T TABLE(
ID INT IDENTITY(1,1),
Visit_DATE_TIME varchar(20))

12 hrs Data insertion:

INSERT INTO @T VALUES('24-MAY-2020 10:30PM')
INSERT INTO @T VALUES('25-MAY-2020 11:30AM')

24 hrs Data insertion:

INSERT INTO @T VALUES('26-MAY-2020 16:30')
INSERT INTO @T VALUES('28-MAY-2020 22:30')

Query

SELECT *, CAST(VISIT_DATE_TIME as DATE) as Visit_Date ,
CAST(VISIT_DATE_TIME as TIME) as Visit_Time_24,
RIGHT(CONVERT(DATETIME,RTRIM(VISIT_DATE_TIME), 109),7) as Visit_Time_12
FROM @T