验证where子句中的列

Question

我需要验证2列，但有时第二列是空的 然后我需要验证第二列，如果它不是空的，否则它将只验证第一列

SELECT * 
FROM table 
WHERE column1 = $_GET['id'] 
and column2 IS NOT NULL = $_GET['id']

Answer 1

这是你想要的逻辑吗？

SELECT *
FROM table
WHERE column1 = $_GET['id'] and
      (column2 IS NULL or column2 = $_GET['id']);

Answer 2

SELECT IF(column1 IS NULL, column2, column1)
FROM table 
WHERE column1 = $_GET['id'] OR column2 = $_GET['id']