sql - MySQL - How to add index to certain column? -


how add index column?

alter table table_name add index (column_name) alter table table_name add key (column_name)

which 1 correct? , can explain differences between them?

in mysql documentation alter table, can find:

| add {index|key} [index_name]         [index_type] (index_col_name,...) [index_option] ...

it's not stated explicitly, index , key synonyms in context. there no differences between them.


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