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';
