MySQL index
MySQL creates and deletes indexes
Create a normal index:
Alter table student add index index_dept (dept (8))
Create a unique index
Create unique index uni_ind_name on student (name)
Create an index based on the first n characters of the column
Create index index_dept on student (dept (8))
Create a federated index based on multiple columns
Create index ind_name_dept on student (name,dept)
Create a federated index based on the first n characters of multiple columns
Create index ind_name_dept on student (name (8), dept (10))
Delete a normal index
Alter table student drop index index_dept
Drop index index_dept on student