Q41. Sorting direction keywords?
In the SQL `ORDER BY` clause, sorting direction is controlled by two keywords: 1. **`ASC` (Ascending)**: Sorts from lowest to highest (1 to 9, A to Z, oldest date to newe...
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Q42. Default sort order if not specified?
If no direction keyword is specified in an `ORDER BY` clause, the default sort order is **`ASC` (Ascending)**: ```sql -- These two queries produce identical ordering: SEL...
Q43. Top 3 students by mark?
```sql -- MySQL / PostgreSQL SELECT name, mark FROM Students ORDER BY mark DESC LIMIT 3; -- SQL Server SELECT TOP 3 name, mark FROM Students ORDER BY mark DESC; -- Oracle...
Q44. Sort Customers descending by FirstName?
To sort the `Customers` table in descending alphabetical order (Z to A) by `FirstName`, append `ORDER BY FirstName DESC`: ```sql SELECT * FROM Customers ORDER BY FirstNam...
Q45. Correct GROUP BY syntax?
```sql SELECT name, COUNT(name) FROM customers GROUP BY name; ``` In standard SQL (and MySQL 5.7+ with `ONLY_FULL_GROUP_BY`), any non-aggregated column in SELECT must app...
Q46. WHERE vs HAVING?
| WHERE | HAVING | |-------|--------| | Filters **rows** | Filters **groups** | | Executes **before** GROUP BY | Executes **after** GROUP BY | | Cannot use aggregates | C...
Q47. What is JOIN used for?
A **`JOIN`** clause in SQL combines rows from two or more tables based on a related column between them (typically a Foreign Key referencing a Primary Key). ### The Need ...
Q48. Most common type of join?
The **`INNER JOIN`** is the most widely used type of join in relational database systems. In fact, `INNER` is the default join type in standard SQL—writing `FROM A JOIN B...
Q49. What are different JOINs in SQL?
1. **INNER JOIN** — matching rows only 2. **LEFT (OUTER) JOIN** — all left + matched right 3. **RIGHT (OUTER) JOIN** — all right + matched left 4. **FULL OUTER JOIN** — a...
Q50. Which is NOT TRUE about the ON clause?
The `ON` clause specifies the join condition. It improves readability over the old comma-syntax, supports multi-column joins (`ON a.id = b.id AND a.type = b.type`), and i...