CURTIME() returns the TIME part of the current time.
NOW() returns the date and time portions as a timestamp in various formats, depending on how it was requested
Example
mysql> SELECT NOW(),CURDATE(),CURTIME();
+———————+————+———–+
| NOW() | CURDATE() | CURTIME() |
+———————+————+———–+
| 2012-06-18 14:14:01 | 2012-06-18 | 14:14:01 |
+———————+————+———–+
1 row in set (0.03 sec)
CURTIME() returns the TIME part of the current time.
NOW() returns the date and time portions as a timestamp in various formats, depending on how it was requested
Example
mysql> SELECT NOW(),CURDATE(),CURTIME();
+———————+————+———–+
| NOW() | CURDATE() | CURTIME() |
+———————+————+———–+
| 2012-06-18 14:14:01 | 2012-06-18 | 14:14:01 |
+———————+————+———–+
1 row in set (0.03 sec)
CURDATE() returns the DATE part of the current time.
NOW() returns the date and time portions as a timestamp in various formats, depending on how it was requested
Example
mysql> SELECT NOW(),CURDATE(),CURTIME();
+———————+————+———–+
| NOW() | CURDATE() | CURTIME() |
+———————+————+———–+
| 2012-06-18 14:14:01 | 2012-06-18 | 14:14:01 |
+———————+————+———–+
1 row in set (0.03 sec)
CURDATE() returns the DATE part of the current time.
NOW() returns the date and time portions as a timestamp in various formats, depending on how it was requested
Example
mysql> SELECT NOW(),CURDATE(),CURTIME();
+———————+————+———–+
| NOW() | CURDATE() | CURTIME() |
+———————+————+———–+
| 2012-06-18 14:14:01 | 2012-06-18 | 14:14:01 |
+———————+————+———–+
1 row in set (0.03 sec)
mysql> SHOW VARIABLES LIKE ‘have_blackhole_engine’;
When we create BLACKHOLE table the server will create file with name starts with table name with extension .frm . No other tables will be generated as it stores nothing .
It supports all types of indexes .
Though nothing is stored , the query statements get stored if binary logs are enabled .
It does not support AUTO INCREMENT
When you create an ARCHIVE table, the server creates a table format file in the database directory. The file begins with the table name and has an .frm extension. The storage engine creates other files, all having names beginning with the table name. The data and metadata files have extensions of .ARZ and .ARM, respectively. An .ARN file may appear during optimization operations.
The ARCHIVE engine supports INSERT and SELECT, but not DELETE, REPLACE, or UPDATE. It does support ORDER BY operations, BLOB columns
When you create an ARCHIVE table, the server creates a table format file in the database directory. The file begins with the table name and has an .frm extension. The storage engine creates other files, all having names beginning with the table name. The data and metadata files have extensions of .ARZ and .ARM, respectively. An .ARN file may appear during optimization operations.
The ARCHIVE engine supports INSERT and SELECT, but not DELETE, REPLACE, or UPDATE. It does support ORDER BY operations, BLOB columns
Run the following command
mysql> SHOW VARIABLES LIKE 'have_archive';