mysql - 如果列值为 null MySQL，如何返回特定字符串

Question

如果列值为 null MySQL，我如何返回一个特定的字符串？所以基本上在下面的实例中，有时值“tableA.Name”有时为 Null，因为用户忘记填写它。

在这种情况下，我不想返回 Null，而是想要某种 if 语句来检查值是否为 null，然后说“Name not assigned”

我的 MySQL 查询:

SELECT `shoes_item`.Product_Name, `run_task`.Name, `shoes_item`.Notes FROM `shoes_item` As test
LEFT OUTER JOIN `run_item`
ON `run_item`.shoes_ID = `shoes_item`.shoes_ID
LEFT OUTER JOIN `run_details`
ON `run_details`.run_Item_ID = `run_item`.run_Item_ID

Answer 1

他是你要找的人吗？

SELECT IFNULL(`shoes_item`.Product_Name,"name not assigned") as product_name, `run_task`.Name, `shoes_item`.Notes FROM `shoes_item` As test
LEFT OUTER JOIN `run_item`
ON `run_item`.shoes_ID = `shoes_item`.shoes_ID
LEFT OUTER JOIN `run_details`
ON `run_details`.run_Item_ID = `run_item`.run_Item_ID