How to Efficiently Retrieve Rows with Non-Empty Column Values in MySQL?

Retrieving Non-Empty Column Values in MySQL

In MySQL, selecting records where specific columns contain non-empty values can be achieved through comparison with an empty string.

Query Optimization:

Consider the following query:

select phone, phone2
from jewishyellow.users
where phone like '813%'
and phone2

This query aims to retrieve rows where the phone number begins with '813' and phone2 is not empty. However, it suffers from optimization issues.

Optimized Solution:

To optimize the query, compare the phone2 column directly with an empty string:

select phone, phone2 
from jewishyellow.users 
where phone like '813%' and phone2<>''

By using the <> (not equal to) operator, the query excludes rows where phone2 is empty, including those with NULL values. This approach improves query performance by avoiding the evaluation of NULLs.

Note:

It's essential to remember that NULL values are interpreted as false in MySQL. Therefore, the query will not retrieve rows where phone2 has a NULL value, even though they technically contain data.

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