SQLite選擇兩列作爲一個爲空

Question

如果在其中一個列中存在空值，我將如何組合這兩列？

SELECT (column1 || " " || column2) AS expr1 FROM your_table; 

我想輸出是：

Answer 1

SELECT (COALESCE(column1,'') || " " || COALESCE(column2, '')) AS expr1 FROM your_table;