How to Generate Unique 8-Character Alphanumeric Strings in MySQL?

Generate unique 8-character random string in MySQL

How to efficiently generate a unique 8-character alphanumeric license plate number for the vehicle table (vehicles) in the MySQL database? This article explores several options.

One solution is to loop the generation and check until a unique value is found. However, this method is less efficient, especially when the number of vehicles increases.

Another more efficient solution is to use the MySQL built-in function UUID() combined with the LEFT() function. UUID()Generate a pseudo-random UUID, and the LEFT() function intercepts its first 8 characters. This method is relatively efficient, but the generated string is not completely random and may have a certain order.

The following pseudocode demonstrates this method:

<code class="language-sql">DO 
    SELECT LEFT(UUID(), 8) INTO @plate;
    INSERT INTO plates (@plate);
WHILE there_is_a_unique_constraint_violation
-- @plate 即为新生成的唯一车牌号</code>

In order to improve the randomness, it is recommended to use MD5(RAND()) or RANDOM_BYTES() instead of UUID(). RANDOM_BYTES() function can generate a more random sequence of bytes and convert it to an alphanumeric string, resulting in better randomness and uniqueness.

Through the above method, developers can effectively generate unique and random 8-character string license plate numbers for vehicles in the MySQL database, ensuring that each vehicle has a unique identity.

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