phpMyAdmin displays and allows editing of column defaults and auto-increment settings through the table structure view. 1. Default values are shown in the "Default" column, where you can edit them via dropdown or input field, supporting NULL, CURRENT_TIMESTAMP, USER(), or custom values. 2. Functions like NOW() must be entered correctly, often without parentheses. 3. If a column is NOT NULL with no default, MySQL may throw errors when inserting missing values. 4. Auto-increment settings appear under the "Extra" column, editable only through the column edit form, requiring numeric types and indexing. 5. Only one column per table can be auto-increment, typically tied to a primary key. 6. Changing the auto-increment start value requires table operations or manual SQL. 7. Always verify column properties and consider MySQL version differences for consistent behavior.

phpMyAdmin shows and lets you edit column defaults and auto-increment settings in a pretty straightforward way, especially if you're used to working with MySQL or MariaDB through a graphical interface.

How DEFAULT Values Are Displayed and Edited

When you look at a table structure in phpMyAdmin (by clicking the "Structure" tab), each column's default value is listed under the "Default" column.

If a column has a defined default — like CURRENT_TIMESTAMP, 0, 'hello', or NULL — it’ll show up right there. If not, it might say None or just be blank depending on how the column was set up.

To change the default:

• Click the pencil icon next to the column
• In the “Default” dropdown or input field:
  • You can pick from common options like NULL, CURRENT_TIMESTAMP, or USER()
  • Or type a custom value directly

A few things to note:

• Literal values like strings or numbers should be entered without quotes
• Functions like NOW() work but need to be written correctly — sometimes without parentheses, depending on server version
• If the column allows NULL and no default is set, MySQL will use NULL automatically when inserting new rows without that value

Handling AUTO_INCREMENT Settings

The AUTO_INCREMENT property for a column is also shown in the "Structure" view, typically under the "Extra" column. If a column has AUTO_INCREMENT, it'll say so there.

Only one column per table can be set as auto-increment, and it must be a numeric type like INT or BIGINT. Also, it usually needs to be part of a primary key or have an index.

You can't always directly toggle the AUTO_INCREMENT setting in a simple click unless you're using the edit form for the column. When editing:

• Look for the checkbox labeled something like “Auto Increment”
• Toggling it will generate the appropriate ALTER TABLE SQL command behind the scenes

Some important points:

• If you try to add AUTO_INCREMENT to a column that doesn’t meet requirements, phpMyAdmin will show an error
• If you remove it from a column that’s currently being used by the table for auto-incrementing, future inserts won’t auto-generate values unless specified
• Changing the auto-increment value for the whole table (like starting from a higher number) isn’t done per column in this interface — instead, you do that in the table operations or by running SQL manually

Tips When Working With These Settings

Here are a few real-world tips based on common issues:

• Always double-check whether a column allows NULL before assuming the default will kick in — if NOT NULL and no default is set, MySQL might throw errors during inserts.
• Be careful with AUTO_INCREMENT fields when copying or altering tables — sometimes the auto-increment behavior doesn’t carry over unless explicitly set.
• If you’re editing via the SQL tab instead of the form, remember the syntax:
  • For defaults: DEFAULT 'value' or DEFAULT CURRENT_TIMESTAMP
  • For auto-increment: AUTO_INCREMENT=12345 at the end of an ALTER TABLE statement

Also, keep in mind that some features depend on your MySQL version and phpMyAdmin configuration — older versions might handle defaults differently, especially around functions like CURRENT_TIMESTAMP.

Basically, the interface makes these settings accessible, but understanding how MySQL interprets them is key to avoiding surprises.

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