DATEADD Function - SQL Server to MySQL Migration

In SQL Server, you can use DATEADD function to add an interval in the specified units to the datetime value. In MySQL, you can use TIMESTAMPADD function.

Note that unit values can be different in SQL Server DATEADD and MySQL TIMESTAMPADD functions.

SQL Server:

  -- Add 3 days
  SELECT DATEADD(dd, 3, '2022-09-06'); 
  # 2022-09-09 00:00:00.000

MySQL:

  -- Add 3 days
  SELECT TIMESTAMPADD(day, 3, '2022-09-06'); 
  # 2022-09-09

You can map unit values between SQL Server DATEADD and MySQL TIMESTAMPADD functions as follows:

In SQL Server you can specify an integer instead of the datetime expression. In this case it assumes the number of days since 1900-01-01 and can be negative.

SQL Server:

  -- Add 1 day since 1900-01-01
  SELECT DATEADD(dd, 1, 0); 
  # 1900-01-02 00:00:00.000
 
    -- Add 1 day since 1900-01-01 - 10 days
  SELECT DATEADD(dd, 1, -10); 
  # 1899-12-23 00:00:00.000

You have to specify the datetime explicitly in MySQL, you cannot use an integer:

MySQL:

    -- Add 1 day since 1900-01-01
  SELECT TIMESTAMPADD(day, 1, '1900-01-01'); 
  # 1900-01-02
 
    -- Add 1 day since 1900-01-01 - 10 days
  SELECT TIMESTAMPADD(day, 1, ADDDATE('1900-01-01', -10)); 
  # 1899-12-23

For more information, see SQL Server to MySQL Migration.