sql: knowledge point record 2

(1) Advantages and disadvantages of indexes

 

(2) Index classification and index creation command statement

 

Look at the indexes in the table:

 

 

(3) Index structure

 

 

 

 (4) Which situations are suitable for indexing

 

(5) Which situations are not suitable for indexing

 

 (6) Prerequisite knowledge of performance analysis

 

 

 

 (7) Introduction to use of explain

 

 

 

how to use:

 

 

 

 

(8) Introduction to the id of explain