Vii. MySQL Index selection

1. myisam,bdb,innodb,memory single table supports at least 16 indexes2.Create IndexId_index onEMP (ID) Create an index of an ID field named Id_index for the EMP table3.Drop IndexId_index onEMP Delete id_index index of EMP table4. Explain xxxxxxx, you can view the relevant execution results for optimizing the table5The most appropriate index column is the "condition column" instead of "select column" such asSelectName fromEmpwhere  Year >=  the; It's best to create an index on the year field instead of the Name field6. Using indexed fields, the value of the field is best unique, because the more unique the index, the greater the significance7The. Btree index is accessed through the index, while the hash index is scanned with a full table