AUTOINCREMENTFeldern

AUTOINCREMENT Feldern are database columns automatically assigned unique numeric values when a new row is inserted. This mechanism removes the need for explicit value specification and guarantees each record a distinct identifier. The term is used especially in contexts where the database system enforces an incremental sequence upon insertion, such as the AUTOINCREMENT keyword in SQLite or the AUTO_INCREMENT column type in MySQL. In these systems the database engine internally maintains a counter; each insert operation increments the counter and returns the new value, which is stored in the column.

When defining a table, a column declared as INTEGER PRIMARY KEY AUTOINCREMENT in SQLite becomes a primary key that auto‑increments. MySQL uses INT AUTO_INCREMENT PRIMARY KEY. In PostgreSQL the equivalent is a SERIAL or BIGSERIAL data type, which automatically creates a sequence object and sets the column’s default value to nextval of that sequence. The auto‑incremented value can be referenced immediately after an insert using the RETURNING clause or functions such as LAST_INSERT_ID() in MySQL and currval in PostgreSQL.

AUTOINCREMENT Feldern are commonly employed for surrogate keys, simplifying joins and improving index performance. However, they should not be relied on for cryptographic identifiers or in distributed environments where concurrent generation might produce gaps. Careful consideration of sequence reset policies and potential fragmentation is advisable.