Re: Query table and retriving results

[Rick James]

> where Entry_Date like '2016%'
> where left(entry_date,4)='2016'

Both require conversion of `Entry_date`, so neither can use an index. This can use an index:

    WHERE entry_date >= '2016-01-01'
      AND entry_date  < '2016-01-01' + INTERVAL 1 YEAR

But _will_ it use an index? It depends on the distribution of dates in the table and the index and whether the WHERE has other clauses. You can try

    INDEX(entry_date)

For further discussion, please provide SHOW CREATE TABLE and the SELECT in question. You could also read http://mysql.rjweb.org/doc.php/index_cookbook_mysql .