Question

Delphi XE2 and MySql.

My previous question led to the recommendation that I should be using MySql’s native TIMESTAMP datatype to store date/time.

Unfornately, I can’t seem to find any coding examples, and I am getting weird results.

Given this table:

mysql> describe test_runs;
+------------------+-------------+------+-----+---------------------+-------+
| Field            | Type        | Null | Key | Default             | Extra |
+------------------+-------------+------+-----+---------------------+-------+
| start_time_stamp | timestamp   | NO   | PRI | 0000-00-00 00:00:00 |       |
| end_time_stamp   | timestamp   | NO   |     | 0000-00-00 00:00:00 |       |
| description      | varchar(64) | NO   |     | NULL                |       |
+------------------+-------------+------+-----+---------------------+-------+
3 rows in set (0.02 sec)

I woudl like to :

• declare a variable into which I can store the result of SELECT CURRENT_TIMESTAMP – what type should it be? TSQLTimeStamp?
• insert a row at test start which has start_time_stamp = the variable above
• and end_time_stamp = some “NULL” value … “0000-00-00 00:00:00”? Can I use that directly, or do I need to declare a TSQLTimeStamp and set each field to zero? (there doesn’t seem to be a TSQLTimeStamp.Clear; – it’s a structure, not a class
• upadte the end_time_stamp when the test completes
• calcuate the test duration

Can somene please point me at a URL with some Delphi code whcich I can study to see how to do this sort of thing? GINMF.

Answer 1

I don’t know why you want to hassle around with that TIMESTAMP and why you want to retrieve the CURRENT_TIMESTAMP just to put it back.

And as already stated, it is not a good advice to use a TIMESTAMP field as PRIMARY KEY.

So my suggestion is to use this TABLE SCHEMA

CREATE TABLE `test_runs` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
    `start_time_stamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
    `end_time_stamp` timestamp NULL DEFAULT NULL,
    `description` varchar(64) NOT NULL,
    PRIMARY KEY (`id`)
);

Starting a test run is handled by

INSERT INTO test_runs ( description ) VALUES ( :description );
SELECT LAST_INSERT_ID() AS id;

and to finalize the record you simply call

UPDATE test_runs SET end_time_stamp = CURRENT_TIMESTAMP WHERE id = :id