docs(jdbc): explain core requirements for Java program to talk with a database

What
- Added conceptual explanation of the **4 core elements** required for Java ↔ Database communication:
  1. **Driver** → translator that bridges Java types with database types.
  2. **Connection** → channel between Java program and database.
  3. **Statement** → object to send SQL queries (Statement, PreparedStatement, CallableStatement).
  4. **ResultSet** → container holding results of SQL queries, iterated row by row.
- Included a short overview of JDBC components:
  - DriverManager (manages drivers and establishes connections).
  - Connection (represents an active session).
  - Statement (executes SQL).
  - ResultSet (iterates returned data).
- Clarified the flow: Driver loads → Connection opens → Statement executes → ResultSet retrieves.

Why
- Beginners often struggle with understanding how Java applications communicate with databases.
- Provides a **clear mental model** of the JDBC pipeline from query submission to result retrieval.
- Reinforces separation of responsibilities:
  - Driver = bridge,
  - Connection = link,
  - Statement = query sender,
  - ResultSet = result reader.

How
- Explained each component in detail with its role and interaction.
- Presented the "step-by-step pipeline":
  1. Load driver.
  2. Establish connection.
  3. Create and execute statement.
  4. Process results with ResultSet.
- Highlighted importance of DriverManager as the central manager for JDBC drivers.

Key Points
- **Driver**: Converts Java datatypes into DB-compatible datatypes and registers with DriverManager.
- **Connection**: Opens session; required for all SQL execution.
- **Statement**: Executes queries; PreparedStatement/CallableStatement offer better performance and safety.
- **ResultSet**: Provides a cursor to navigate retrieved rows.
- **DriverManager**: Chooses the right driver for the DB.

Real-life Applications
- Web apps connecting to MySQL/Postgres/Oracle.
- Payroll or ERP systems retrieving employee data.
- Report generators iterating over large datasets using ResultSet.
- APIs persisting and retrieving business data securely.

Notes
- Always close `ResultSet`, `Statement`, and `Connection` to free DB resources.
- Prefer **PreparedStatement** for dynamic queries to prevent SQL injection.
- JDBC abstracts DB interaction: the same Java code works with multiple databases by swapping drivers.

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

Author: Someshdiwan

Section28JDBCusingSQLite/JDBC/how a Java program talks to a database.txt renamed to Section28JDBCusingSQLite/JDBC/java program talk with the database program.txt

@@ -1,18 +1,20 @@
-What are the things required to java program talk with the database program.
-Ans: Need a driver
+What are the things required to java program talk with the database program?
+Ans:
+Need a driver
 Need a connection
 Need a statement(SQL).
 
 In last Result Set.
 
-Drivers: Helps the establish the connection. Using JAVA Program help to establish connection to the database.
-it understand the JAVA And other database lang.
+Drivers: Helps the establish the connection.
 
+Using JAVA Program helps to establish connection to the database. it understands the JAVA And another database lang.
 
-Driver will converted datatypes of java to the database of datatype.
 
-Using the driver , We create statement using a connection and using this statement we write our Query.
-Query is send via connection, to the database and it execute and results is return.
+Driver will convert datatypes of java to the database of datatype.
+
+Using the driver, We create a statement using a connection, and using this statement, we write our Query.
+Query is sent via connection, to the database, and it executes, and results is return.
 
 how a Java program talks to a database:
 
@@ -40,8 +42,7 @@ Essentially:
 - The Statement sends queries.  
 - The ResultSet carries the returned data.
 
-
-Short Explanation of JDBC Components
+Short Explanation of JDBC Components:
 1. Driver  
    - Acts as a bridge between your Java application and the database.  
    - Understands Java data types and converts them to the database’s data types (and vice versa).
@@ -60,4 +61,4 @@ Short Explanation of JDBC Components
 
 5. ResultSet
    - Represents the data returned by your SQL queries.  
-   - Allows you to iterate over rows of data and read individual columns.
+   - Allows you to iterate over rows of data and read individual columns.