MySQL date range fills missing values
Suppose you have a table with two columns (date and score) and you want to fill in missing dates to get a continuous sequence of values. For example, if your table currently contains the following data:
<code>日期 分数 ----------------- 2010-08-01 19 2010-08-02 21 2010-08-04 14 2010-08-07 10 2010-08-10 14</code>
You want to fill the missing dates (2010-08-03, 2010-08-05 and 2010-08-06) with 0s to get the following result:
<code>日期 分数 ----------------- 2010-08-01 19 2010-08-02 21 2010-08-03 0 2010-08-04 14 2010-08-05 0 2010-08-06 0 2010-08-07 10 2010-08-10 14</code>
To achieve this you can use the following query:
SELECT x.ts AS timestamp, COALESCE(y.score, 0) AS cnt FROM (SELECT DATE_ADD('2010-06-06', INTERVAL n.id - 1 DAY) AS ts FROM numbers n WHERE DATE_ADD('2010-06-06', INTERVAL n.id -1 DAY) < '2010-08-11') x LEFT JOIN your_table y ON DATE(x.ts) = DATE(y.date);
Here’s a breakdown of the query:
- Create a table of numbers (numbers) with auto-incrementing values.
- Use DATE_ADD to construct a list of dates from a specified starting date ('2010-06-06' in the example) and increment the number of days based on the id of the number in the numbers table.
- Use LEFT JOIN to merge the list of dates with your original table y based on the date part.
- Use COALESCE to replace any null values in y.score with 0.
- You can use DATE_FORMAT to change the date format if needed.
Please replace your_table
with your actual table name. Make sure you have a table named numbers
that contains an auto-increment column named id
that contains consecutive integers starting at 1. If not, you need to create one first. For example: CREATE TABLE numbers (id INT AUTO_INCREMENT PRIMARY KEY);
Then insert a sufficient number of records to cover your date range.
The above is the detailed content of How to Fill Missing Dates in a MySQL Range with Zero Values?. For more information, please follow other related articles on the PHP Chinese website!

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