CREATE TABLE table_name (
col1 int(11) PRIMARY KEY
)
CREATE TABLE table_name (
col1 int(11),
col2 int(11),
PRIMARY KEY (col1, col2)
)
ALTER TABLE table_name ADD PRIMARY KEY (col1)
ALTER TABLE table_name DROP PRIMARY KEY
CREATE TABLE table_name (
col1 int(11),
col2 int(11),
UNIQUE KEY unique_name (col1, col2)
)
ALTER TABLE table_name ADD UNIQUE KEY unique_name (col1, col2)
ALTER TABLE table_name DROP INDEX unique_name