The following intro-level SQL problems are about ‘Filtering (HAVING)’. LeetCode 182Duplicate Emails (Easy) [link] Using

The following intro-level SQL problems are about ‘Control Flow’. LeetCode 1158Market Analysis I (Medium) [link] SELECT U

The following intro-level SQL problems are about ‘Function (COUNT, MAX, MIN)’. LeetCode 511Game Play Analysis I (Easy)

The following intro-level SQL problems are about ‘Join (JOIN or WHERE)’. Recall DATEDIFF, WHERE IS. Recall (INNER) JOIN

The following intro-level SQL problems are about manipulating ‘string’ by GROUP_CONCAT, CONCAT, LEFT, RIGHT, SUBSTRING,

The following intro-level SQL problems are about ‘ordering (ORDER BY)’ and ‘editing (CASE WHEN)’. More: DELETE and UPDAT

The following intro-level SQL problems are about ‘combining (UNION) and querying’ and ‘selecting (HAVING)’. More: LIMIT

The following intro-level SQL problems are about ‘selecting (WHERE)’. LeetCode 183Customers Who Never Order (Easy) [link

SQL Window FunctionsWindow function performs after “FROM, JOIN, WHERE, GROUP BY, HAVING”, before “ORDER　BY, LIMIT, SELEC

SQL Categories1 Computing Ratios Compute ratio / percentage Given user activities history / system logs Examples Calcula

Solution to LeetCode 62 Unique Paths & LeetCode 63 Unique Paths II . LeetCode 62Unique Paths (Medium) [link] 1] Recu

Solution to LeetCode 120 Triangle. LeetCode 120Triangle (Medium) [link] Define dp[i][j] as the minimum path sum from top