docs(sql): add dedicated folder for WHERE clause with detailed explanation

What
- Created `WHERE Clause In SQL` folder to document filtering records in SQL queries.
- Explained how `WHERE` is used to apply conditions before grouping or sorting.
- Added syntax, examples, and operator usage (comparison, logical, pattern matching).
- Clarified how `WHERE` differs from `HAVING`.

Why
- Filtering data is the foundation of SQL querying.
- Developers often confuse `WHERE` with `HAVING` or misuse operators (`=`, `LIKE`, `IN`, `BETWEEN`).
- Clear reference improves query accuracy and performance.

How
- Structured documentation into:
  - Definition and purpose of `WHERE`.
  - Basic syntax:
    `SELECT * FROM employees WHERE dept = 'HR';`
  - Comparison operators (`=`, `!=`, `<`, `>`, `<=`, `>=`).
  - Logical operators (`AND`, `OR`, `NOT`).
  - Special operators (`BETWEEN`, `IN`, `LIKE`, `IS NULL`).
- Showed ordering of execution: `FROM → WHERE → GROUP BY → HAVING → ORDER BY`.

Key notes
- `WHERE` filters rows before grouping or aggregation.
- Case sensitivity may vary depending on SQL dialect and collation.
- Always use parameterized queries in applications to prevent SQL injection.

Real-life applications
- Banking: filter accounts with balance > 1,00,000.
- HR: find employees hired after 2020.
- Retail: fetch products priced between 100 and 500.
- Education: list students who scored above 80 in Math.

Future improvements
- Add combined examples using multiple operators.
- Include advanced filtering with subqueries inside `WHERE`.
- Compare performance implications of indexed vs non-indexed columns.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section28JDBCusingSQLite/Clauses in SQL/WHERE clause in SQL/A in name.png renamed to Section28JDBCusingSQLite/Clauses in SQL/WHERE Clause In SQL/A in name.png

@@ -4,7 +4,6 @@ The conditions can include various operators and logical connectors.
 
 SQL WHERE Clause with Various Conditions.
 
-
 list of the conditions you can use in the WHERE clause:
 
 = : Equal to a specific value.
@@ -33,4 +32,4 @@ NOT : Negates a condition.
 
 IS NULL : Checks for NULL values.
 
-IS NOT NULL : Checks for non-NULL values.
+IS NOT NULL : Checks for non-NULL values.