Adventures in Machine Learning

Mastering Time Extraction and Conversion in MySQL

Extracting Time from a String Value in MySQL

Have you ever come across a situation where you need to extract specific time values from a string in MySQL? It can be a tedious task, especially when dealing with large amounts of data.

However, MySQL provides two functions – STR_TO_DATE and DATE_FORMAT, which can be used to convert string values into datetime format and extract time values from them, respectively. In this article, we will discuss these two functions in detail and provide examples of their usage.

Converting String to Datetime Format Using STR_TO_DATE Function

The STR_TO_DATE function is used to convert a string value into datetime format. It takes two arguments – the string value that needs to be converted and the format of the datetime value in the string.

The function returns a datetime value if the conversion is successful, else NULL. Let us consider an example.

Suppose we have a string value, “2021-11-25 21:25:30”, and we want to convert it into datetime format. We can use the following query:

“`

SELECT STR_TO_DATE(‘2021-11-25 21:25:30’, ‘%Y-%m-%d %H:%i:%s’);

“`

Here, ‘%Y-%m-%d %H:%i:%s’ is the format of the datetime value in the string value.

The ‘%Y’ specifier represents the year, ‘%m’ represents the month, ‘%d’ represents the day, ‘%H’ represents the hour, ‘%i’ represents the minute, and ‘%s’ represents the second. The output of the above query will be:

“`

2021-11-25 21:25:30

“`

Extracting Time Using DATE_FORMAT Function

The DATE_FORMAT function is used to extract a specific time value from a datetime value. It takes two arguments – the datetime value and the format of the time value that needs to be extracted.

The function returns a string value. Let us take the same example mentioned above.

Suppose we have a datetime value, “2021-11-25 21:25:30”, and we want to extract the time value in the format ‘hh:mm:ss’. We can use the following query:

“`

SELECT DATE_FORMAT(‘2021-11-25 21:25:30’, ‘%H:%i:%s’);

“`

Here, ‘%H:%i:%s’ is the format of the time value that needs to be extracted.

The ‘%H’ specifier represents the hour, ‘%i’ represents the minute, and ‘%s’ represents the second. The output of the above query will be:

“`

21:25:30

“`

Syntax and Parameters for STR_TO_DATE and DATE_FORMAT Functions in MySQL

Now that we have seen how to use these two functions, let us take a closer look at their syntax and parameters.

Parameters for STR_TO_DATE Function

The following are the most commonly used parameters for the STR_TO_DATE function:

– %Y – 4-digit year

– %y – 2-digit year

– %m – month (01-12)

– %b – abbreviated month name (Jan, Feb, Mar, etc.)

– %c – month (1-12)

– %d – day (01-31)

– %e – day (1-31)

– %j – day of year (001-366)

– %H – hour (00-23)

– %h – hour (01-12)

– %i – minute (00-59)

– %s – second (00-59)

– %p – AM or PM

The parameters are used within the format string in the order that they appear in the datetime value. For example, if the datetime value is in the format ‘dd-mm-yyyy hh:mm:ss’, the format string would be ‘%d-%m-%Y %H:%i:%s’.

Syntax and Parameters for DATE_FORMAT Function

The following are some of the format specifier characters that can be used in the DATE_FORMAT function:

– %H – hour (00-23)

– %h – hour (01-12)

– %i – minute (00-59)

– %s – second (00-59)

– %T – time in 24-hour format (hh:mm:ss)

Apart from these format specifier characters, punctuation marks such as colon (:) and hyphen (-) can also be used in the format string. For example, to display the time value in the format ‘hh:mm:ss’, we can use the format string ‘%H:%i:%s’.

To display the time value in 24-hour format with seconds, we can use the format string ‘%T’.

Conclusion

In conclusion, the STR_TO_DATE and DATE_FORMAT functions provide a convenient way to convert string values into datetime format and extract time values from them, respectively. By understanding the syntax and parameters of these functions, we can perform these operations efficiently and accurately.

These functions are invaluable tools for anyone who works extensively with datetime values in MySQL. In conclusion, the STR_TO_DATE and DATE_FORMAT functions in MySQL are essential tools for converting string values into datetime format and extracting time values from them.

By understanding the syntax and parameters of these functions, we can perform these operations efficiently and accurately. These functions are invaluable for anyone who works extensively with datetime values.

Remember to use the correct format specifier characters and punctuation marks to get accurate results. We hope this article has helped you gain a better understanding of these functions and how to use them effectively.

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