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What is the maximum number of columns that a primary key can include in a database table?

sobes.tech AI

Answer from AI

The maximum number of columns that can be part of a primary key depends on the specific database management system (DBMS). For example, in MySQL, the limit is up to 16 columns; in PostgreSQL, up to 32; and in Oracle, also up to 32. However, in practice, it is recommended to use the minimal necessary number of columns for the primary key to avoid unnecessary complexity and performance degradation.

Example: in MySQL, you can create a composite primary key from several columns as follows:

CREATE TABLE example (
  col1 INT,
  col2 INT,
  col3 INT,
  PRIMARY KEY (col1, col2, col3)
);

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