MySQL Primary Key

ALTER TABLE tbl_quiz_attempt_master
  DROP INDEX `PRIMARY`;

ALTER TABLE tableName MODIFY COLUMN id INT; /* First you should drop auto increment */
ALTER TABLE tableName DROP PRIMARY KEY; /* Dop primary key */
ALTER TABLE tableName ADD PRIMARY KEY (new_id); /* Set primary key to the new column */
ALTER TABLE tableName MODIFY COLUMN new_id INT AUTO_INCREMENT; /* Set auto increment to the new 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,
    ...
);

SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'Your Database'
  AND TABLE_NAME = 'Your Table name'
  AND COLUMN_KEY = 'PRI';


SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'Your Database'
  AND TABLE_NAME = 'Your Table name'
  AND COLUMN_KEY = 'UNI';