How to Generate a Date Series in MySQL?
Generate date sequence in MySQL
Question:
How to create a date series in MySQL, similar to the generate_series() function in PostgreSQL?
Answer:
MySQL does not have a direct equivalent to generate_series(), but we can achieve similar results by following these steps:
- Create a temporary table containing consecutive numbers.
- Use the adddate() function to add the corresponding date interval to each number.
- Use the date_format() function to format the generated date so that it conforms to the desired format.
The following is a sample query to create a date range from January 1, 2011 to December 31, 2011:
SELECT DATE_FORMAT( ADDDATE('2011-01-01', @num := @num + 1), '%Y-%m-%d' ) AS 日期 FROM 任意表, (SELECT @num := -1) AS num LIMIT 365;
In this query:
-
任意表
is a temporary table containing one or more rows (any table can be used, as only the number of rows is used). -
@num := @num 1
Creates a sequence of consecutive numbers starting from 0. -
ADDDATE('2011-01-01', @num := @num 1)
Add the corresponding date interval to each number. -
DATE_FORMAT()
Format the generated date into the desired format. -
LIMIT 365
Specifies the number of dates to generate (365 for non-leap years).
This method allows us to generate date sequences in MySQL without the need for a separate calendar table. Note that 任意表
can be replaced with any existing table, or used to create temporary data rows. This is a workaround because MySQL itself does not provide direct functions like PostgreSQL SELECT 1 UNION ALL SELECT 1 ...
. generate_series
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