PL/SQL Training in Chennai

PL/SQL is Oracle’s procedural language extension to SQL that allows writing complex programs using variables, loops, and conditional statements. Unlike SQL, which only handles simple data queries and manipulation, PL/SQL supports full programming logic within the database.

A cursor is a pointer used in PL/SQL to navigate and handle query results one row at a time. It lets you retrieve and manipulate multiple rows from a query, handling one record at a time, which is useful in loops or complex data processing tasks.

Implicit cursors are automatically created by Oracle when you execute single-row queries, requiring no extra coding. Explicit cursors are declared by programmers to manage multi-row query results manually and provide more control over fetching and processing data.

Exceptions are handled in the EXCEPTION block, where you catch runtime errors using predefined exceptions like NO_DATA_FOUND or ZERO_DIVIDE, or user-defined exceptions. This ensures graceful error handling and keeps the program running without abrupt termination.

Stored procedures are named PL/SQL blocks stored in the database that perform actions but don’t return values directly. Functions are similar but always return a single value. Both improve code reusability and help in modularizing complex logic.

Triggers are special PL/SQL programs that automatically execute when specific database events occur, such as inserting, updating, or deleting rows in a table. They assist in enforcing business rules, maintaining audit trails, and ensuring data integrity automatically, without the need for manual input.

Performance can be improved by utilizing bulk operations such as BULK COLLECT and FORALL, which minimize context switching between the SQL and PL/SQL engines. Also, minimizing loops, avoiding unnecessary queries, and using efficient SQL statements help speed up processing.

%TYPE is used to declare a variable with the same data type as a specific column in a table, ensuring consistency. %ROWTYPE defines a record that can store an entire row from a table, automatically matching all columns and their data types.

Parameters in PL/SQL subprograms can be passed using three modes: IN (input only), OUT (output only), and IN OUT (both input and output). This controls how data flows between the calling program and the subprogram for better flexibility.