alter table add primary key mysql code example

Example 1: alter table add foreign key mysql

ALTER TABLE orders
ADD 
FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;

Example 2: MySQL Primary Key

Typically, you define the primary key for a table in the CREATE TABLE statement.

If the primary key has one column, you can use the PRIMARY KEY constraint as a column constraint:

CREATE TABLE table_name(
    primary_key_column datatype PRIMARY KEY,
    ...
);

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