Create table t1 (a int check(a0),b int check (b 0), constraint abc check (ab)); If you use the second format and you don't give a name to the constraint, then the constraint will get a auto generated name. This is done so that you can later delete the constraint with ALTER TABLE DROP constraintname. MAC address or media access control address is a unique identifier allotted to a network interface controller (NIC) of a device. It is used as a network address for data transmission within a network segment like Ethernet, Wi-Fi, and Bluetooth. MAC address is assigned to a network adapter at the time of manufacturing. MySQL Workbench is available for Mac OS X and is distributed as a DMG file. The file is named mysql-workbench-oss-version-osx10.5-i686.dmg, where version is the MySQL Workbench version. To install MySQL Workbench on Mac OS X, simply download the file. Double-click the downloaded file. Toad for MySQL increases developer productivity and offers access to a solid community of experts and peers for interactive support. Full Specifications What's new in version 7.3.1.
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The medium access control (MAC) is a sublayer of the data link layer of the open system interconnections (OSI) reference model for data transmission. It is responsible for flow control and multiplexing for transmission medium. It controls the transmission of data packets via remotely shared channels. It sends data over the network interface card.
MAC Layer in the OSI Model
The Open System Interconnections (OSI) model is a layered networking framework that conceptualizes how communications should be done between heterogeneous systems. The data link layer is the second lowest layer. It is divided into two sublayers −
The logical link control (LLC) sublayer
The medium access control (MAC) sublayer
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The following diagram depicts the position of the MAC layer −
Functions of MAC Layer
It provides an abstraction of the physical layer to the LLC and upper layers of the OSI network.
It is responsible for encapsulating frames so that they are suitable for transmission via the physical medium.
It resolves the addressing of source station as well as the destination station, or groups of destination stations.
It performs multiple access resolutions when more than one data frame is to be transmitted. It determines the channel access methods for transmission.
It also performs collision resolution and initiating retransmission in case of collisions.
It generates the frame check sequences and thus contributes to protection against transmission errors.
MAC Addresses
MAC address or media access control address is a unique identifier allotted to a network interface controller (NIC) of a device. It is used as a network address for data transmission within a network segment like Ethernet, Wi-Fi, and Bluetooth.
MAC address is assigned to a network adapter at the time of manufacturing. It is hardwired or hard-coded in the network interface card (NIC). A MAC address comprises of six groups of two hexadecimal digits, separated by hyphens, colons, or no separators. An example of a MAC address is 00:0A:89:5B:F0:11.
By default, XAMPP has no passwords set and it is not recommended to run XAMPP with this configuration as it is accessible to others.
Simply type the following command (as root) to start a simple security check:
sudo /Applications/XAMPP/xamppfiles/xampp security
Now you should see the following dialog on your screen:
XAMPP: Quick security check...
XAMPP: MySQL is accessable via network.
XAMPP: Normaly that's not recommended. Do you want me to turn it off? [yes] yes
XAMPP: Turned off.
XAMPP: Stopping MySQL...
XAMPP: Starting MySQL...
XAMPP: The MySQL/phpMyAdmin user pma has no password set!!!
XAMPP: Do you want to set a password? [yes] yes
XAMPP: Password: ******
XAMPP: Password (again): ******
XAMPP: Setting new MySQL pma password.
XAMPP: Setting phpMyAdmin's pma password to the new one.
XAMPP: MySQL has no root passwort set!!!
XAMPP: Do you want to set a password? [yes] yes
XAMPP: Write the passworde somewhere down to make sure you won't forget it!!!
XAMPP: Password: ******
XAMPP: Password (again): ******
XAMPP: Setting new MySQL root password.
XAMPP: Setting phpMyAdmin's root password to the new one.
XAMPP: The FTP password for user 'nobody' is still set to 'lampp'.
XAMPP: Do you want to change the password? [yes] yes
XAMPP: Password: ******
XAMPP: Password (again): ******
XAMPP: Reload ProFTPD...
XAMPP: Done.
(1) Setting a password will protect the XAMPP demo pages (http://localhost/xampp/) using this password. The user name is 'lampp'!
After running this command, your XAMPP installation should be more secure.