Columns that are foreign keys are indexed (because in a join table query, a judge on comparison is performed).

1. Select a field type

2. Use of string types

3. Select a value type

Index of 4.

5. Index type

##6. Advantages of indexes

##7. Query without index

8. The drawbacks of indexes

9 Which field should be indexed

10 Composite Index

Mysql query optimization

12. Do not use indexes to compare strings with numbers

13. Multi-table query optimization

14.order by

15. Use the same type

16. Rationalization proposals