https://h30306.github.io/blog/tags/sql/Recent content in Sql onHugo -- gohugo.ioenhwork0511@gmail.com (Wei Yi Chung)hwork0511@gmail.com (Wei Yi Chung)© 2026 Wei Yi ChungWed, 21 Oct 2026 00:00:00 +0000https://h30306.github.io/blog/algorithm/sql/Wed, 21 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/algorithm/sql/Combining conditions in SELECT … WHERE, and NULL’s three-valued logic: any comparison with NULL is not true, so use IS NULLhttps://h30306.github.io/blog/leetcode/leetcode-1757/Tue, 23 Dec 2025 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-1757/LeetCode 1757 note: both conditions must hold, so filter with WHERE … AND …https://h30306.github.io/blog/leetcode/leetcode-584/Tue, 23 Dec 2025 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-584/LeetCode 584 note: referee_id != 2 misses NULLs, since comparing with NULL is unknown; add IS NULL explicitly