How can I concatenate strings with primary key IDs during insertion in MySQL?

Concatenating Strings with Primary Key IDs During Insertion

Question:

While inserting data into a MySQL users table, you wish to create usernames that follow a specific format: 'user' userId, where userId is the auto-incrementing primary key field. How can you achieve this effectively?

Answer:

Concatenating a string with an auto-incrementing primary key during insertion requires a two-step approach:

Method 1 (for Non-Auto-Increment IDs):

• Specify the desired username in your PHP code by concatenating 'user' with the user's ID.
• Pass this concatenated username as a parameter for insertion.

Method 2 (for Auto-Increment IDs):

• Perform the initial insertion into the table as usual.
• Execute an immediate UPDATE statement to update the username field with the concatenation of 'user' and the auto-incrementing primary key obtained from the previous insertion.

Note:

• Attempting to use generated columns in MySQL 5.7 to achieve this will yield an error: "Generated column 'username' cannot refer to auto-increment column."
• Concatenating strings with primary key IDs that are not auto-incrementing is not an issue.

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