DATEDIFF Function - SQL Server to MySQL Migration

In SQL Server, you can use DATEDIFF function to get the datetime difference in specified units. In MySQL, you can use TIMESTAMPDIFF function.

Note that unit values can be different in SQL Server DATEDIFF and MySQL TIMESTAMPDIFF.

SQL Server:

  -- Get difference in days
  SELECT DATEDIFF(dd, '2022-09-01', '2022-09-05'); 
  # 4

MySQL:

  -- Get difference in days
  SELECT TIMESTAMPDIFF(day, '2022-09-01', '2022-09-05'); 
  # 4

You can map unit values between SQL Server DATEDIFF and MySQL TIMESTAMPDIFF functions as follows:

In SQL Server you can specify an integer as the start date. In this case it assumes 1900-01-01 date. You have to specify it explicitly in MySQL, you cannot use an integer:

SQL Server:

  -- Get difference since 1900-01-01 in years (the second parameter is 0)
  SELECT DATEDIFF(yy, 0, '2022-09-05'); 
  # 122

MySQL:

  -- Get difference since 1900-01-01 in years 
  SELECT TIMESTAMPDIFF(year, '1900-01-01', '2022-09-05'); 
  # 122

For more information, see SQL Server to MySQL Migration