By: Mary in MySQL Tutorials on 2023年05月02日 [フレーム]
In SQL, you can use the IS NULL condition to check if a value is NULL. To return 0 when the value is NULL, you can use the COALESCE function or the IFNULL function, depending on the database system you are using.
Here's an example using the COALESCE function:
SELECT COALESCE(column_name, 0) FROM table_name;
This will return the value of column_name, or 0 if column_name is NULL.
Here's an example using the IFNULL function (this is specific to MySQL and SQLite):
SELECT IFNULL(column_name, 0) FROM table_name;
This will return the value of column_name, or 0 if column_name is NULL.
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