问题
I have a database with 13000 rows. Each row contains the column 'date' which is now in this format (example): 2012-09-01 17:53:28, but I want them to be a TIMESTAMP.
What query should I run to update all columns named 'date' from date to timestamp on all rows?
Thanks
回答1:
It's pretty straightforward to convert from one type to another using the ALTER TABLE command:
ALTER TABLE table_name CHANGE old_date new_timestamp TIMESTAMP
This process may take a while to complete if you have a lot of data and a large number of indexes.
I'm not sure why you'd want to switch these to the TIMESTAMP type as that has a much more limited range than DATETIME. The differences are documented and important to know.
回答2:
It's unclear what you are asking for. There exist following datatypes: date, time, datetime and timestamp. And there's UNIX_TIMESTAMP, which is the seconds since 1970-01-01, but I don't think that's what you're after.
I suggest you read this.
The DATETIME type is used for values that contain both date and time parts. MySQL retrieves and displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'.
The TIMESTAMP data type is used for values that contain both date and time parts. TIMESTAMP has a range of '1970-01-01 00:00:01' UTC to '2038-01-19 03:14:07' UTC.
When you want to convert your column date do:
ALTER TABLE yourTable MODIFY COLUMN yourDateColumn TIMESTAMP;
回答3:
SELECT UNIX_TIMESTAMP('2012-09-01 17:53:28');
回答4:
You can just use the UNIX_TIMESTAMP() function to return values as timestamp when doing a query. Like so:
mysqli_query("select UNIX_TIMESTAMP(date) as date from table");
来源：https://stackoverflow.com/questions/12408436/convert-all-colums-in-the-rows-from-date-to-timestamp-mysql