How to Resolve Incorrect Date Comparison Results Using DATE_FORMAT in MySQL?

MySQL Date Comparison with DATE_FORMAT: Resolving the Issue

Question:

When comparing dates using the DATE_FORMAT function, a user encountered unexpected results, with records before the comparison date appearing in the results. How can this issue be resolved?

Analysis:

The problem stems from comparing dates as strings rather than their actual date values. DATE_FORMAT converts dates into strings, which are then compared lexicographically, leading to incorrect results.

Solution:

To compare dates accurately, the query should compare date values directly, using the DATE() function to extract only the date information. The following modified query accomplishes this:

<code class="sql">select date_format(date(starttime),'%d-%m-%Y') from data
where date(starttime) >= date '2012-11-02';</code>

In this query:

• date(starttime) extracts the date part from the starttime column.
• date '2012-11-02' is an example comparison date in the ISO-8601 standard format (yyyy-mm-dd).

By comparing dates directly, the query effectively filters out records where the date is before '2012-11-02'.

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