MySQL MCQs with answers Page - 4

Post MySQL 5.5 (including MySQL 6.0 and beyond), the utf8 character set was replaced by a new character set called utf8mb4. The original utf8 character set in MySQL was capable of storing only up to 3 bytes per character, which was insufficient to store certain characters in the Unicode standard (e.g., some emoji and other characters outside the Basic Multilingual Plane).

The new utf8mb4 character set was introduced to support the full Unicode character set, using up to 4 bytes for each character, which allows it to store all possible Unicode characters, including those outside the Basic Multilingual Plane (BMP).

• utf8 (prior to MySQL 6.0) used 3 bytes for each character.
• utf8mb4 (introduced as a more complete UTF-8 encoding) uses 4 bytes for each character.

Thus, the correct answer to the question is (D) 4 bytes.

Prior to MySQL 6.0, the utf8 character set in MySQL was capable of storing up to 3 bytes per character. This was an implementation of UTF-8 encoding, but it had a limitation: it could only handle characters that fit within the Basic Multilingual Plane (BMP) of Unicode, which includes most characters, but not all.

In this earlier version of utf8, some characters (like certain emoji or less common scripts) could not be represented because they required more than 3 bytes. This limitation was addressed with the introduction of the utf8mb4 character set, which supports up to 4 bytes per character and allows the full range of Unicode characters.

Therefore, prior to MySQL 6.0, the utf8 character set used 3 bytes per character.

In MySQL, the SHOW CHARACTER SETS statement is used to list all available character sets. It will display information about the character sets supported by the MySQL server, including their names and descriptions.

For example:

SHOW CHARACTER SETS;

This will return a list of character sets such as utf8, latin1, utf8mb4, and others available in the MySQL server.

Why the other options are incorrect:

• (B) SHOW COLLATIONS: This command lists the available collations in MySQL, not character sets.
• (C) SHOW CHARACTER SET: This is incorrect because there is no SHOW CHARACTER SET command in MySQL. The correct command is SHOW CHARACTER SETS.
• (D) SHOW COLLATION: Similar to (B), this command lists available collations, not character sets.

Thus, the correct command to find out which character sets are available is (A) SHOW CHARACTER SETS.

MySQL does provide support for Unicode, which allows it to store and manage text in multiple languages. Unicode support is achieved through character sets such as utf8 and utf8mb4. The utf8mb4 character set in MySQL, for example, supports the full range of Unicode characters, including emojis and other characters beyond the Basic Multilingual Plane (BMP).

• utf8: This character set supports most Unicode characters, but it is limited to 3 bytes per character.
• utf8mb4: This character set supports the full Unicode standard, using up to 4 bytes per character, which includes characters such as emojis and other supplementary characters.

Therefore, MySQL does support Unicode, and the correct answer is True.

In MySQL, a single character set can have multiple collations associated with it. A collation defines how strings are compared and sorted within that character set, taking into account factors like case sensitivity and accent sensitivity.

For example:

• The utf8 character set has several collations, such as:
  • utf8_general_ci (case-insensitive, accent-insensitive)
  • utf8_unicode_ci (case-insensitive, accent-insensitive, but with more accurate sorting rules for various languages)
  • utf8_bin (case-sensitive, binary comparison)

Thus, a single character set can have multiple collations, which is why the correct answer is (A) more than 1.