In MySQL how to set index to the table?

问题

In MySQL how to use the Index concept for MySQL tables.

回答1:

Syntax for adding index to existing table.

ALTER TABLE table_name ADD INDEX column_name

A simple example

CREATE TABLE employee_records (name VARCHAR(50), employeeID INT);
CREATE INDEX id_index ON employee_records(employeeID);

creating index while creating table

CREATE TABLE employee_records (
    name VARCHAR(50), 
    employeeID INT, INDEX (employeeID)
);

回答2:

To add an index to a table in MySQL:

ALTER TABLE [table name] ADD INDEX ([column name], ...);

回答3:

ALTER TABLE table_name ADD INDEX index_name (col_name)

OR

CREATE INDEX index_name ON table_name(index_name)

来源：https://stackoverflow.com/questions/6731048/in-mysql-how-to-set-index-to-the-table