Oracle SQL and PL/SQL: SQL*Plus, schemas, DML, joins, PL/SQL blocks, procedures, packages and data management.
The Enterprise Database Leader Oracle Database is a multi-model relational database management system from Oracle Corporation, first released in 1979 and now regarded as the de ...
Choosing an Edition to Learn Oracle Express Edition (XE) is free and enough for learning SQL and PL/SQL. It runs on Windows and Linux and listens on port 1521 by default. ...
Users Own Objects In Oracle, a schema is the set of objects owned by a user. Creating a user and giving it space is the first step of any project. Creating a User Tablespaces A ...
Basic Table Creation VARCHAR2 is Oracle's text type. GENERATED BY DEFAULT AS IDENTITY auto-generates surrogate keys, the modern replacement for the older SEQUENCE + TRIGGER ...
Inserting Data Why COMMIT Matters Oracle is transactional. Changes are invisible to other sessions until you run COMMIT, and you can undo them with ROLLBACK before that. Updating ...
Selecting Data NULL Handling With NVL and NVL2 NVL returns the fallback when the first value is NULL; NVL2 returns different values for NULL and non-NULL. Pagination With ROWNUM ...
ANSI Joins in Oracle Legacy (+) Outer Join Syntax Older Oracle code uses (+) on the outer side of a join: Prefer the modern ANSI syntax, but be ready to read legacy code that uses ...
Aggregating With GROUP BY Analytic (Window) Functions Oracle pioneered analytic functions. They compute a value across a window of rows while keeping each row visible. Lag and ...
The Anatomy of a PL/SQL Block DECLARE: variables and types (optional). BEGIN ... END: the executable statements. EXCEPTION: error handlers (optional). / runs the block in ...
Stored Procedures Stored Functions Packages Group Related Objects Key Points PROCEDURES do work; FUNCTIONS return a value. CREATE OR REPLACE rewrites without losing grants. ...
Triggers Fire on Events :NEW and :OLD expose the new and old row values inside the trigger. Sequences Generate Numbers Indexes Key Points Triggers run automatically before or ...
Transactions Protect Your Data Why Oracle Reads Old Data Oracle uses undo segments and multiversioning. Readers see a consistent snapshot of committed data, so long-running ...