Oracle Identity Column: Examples, Options and ORA-00001 Fix
Create an Oracle identity column with GENERATED ALWAYS or BY DEFAULT ON NULL, get the new ID in PL/SQL, and fix ORA-00001 with START WITH LIMIT VALUE.
PLSQL
PL/SQL and Oracle Database articles: how triggers work and how to write them, moving through result sets with cursors and collections, and how Oracle Database is put together.
PRAGMA AUTONOMOUS_TRANSACTION in Oracle: Examples and Pitfalls
Learn PRAGMA AUTONOMOUS_TRANSACTION in Oracle with examples: error logging that survives rollback, audit triggers, and fixes for ORA-06519.
Oracle Global Temporary Table: Examples, Indexes and Stats
Learn how an Oracle global temporary table works, ON COMMIT DELETE vs PRESERVE ROWS, indexes, ORA-14452, statistics and private temporary tables.
Oracle Delete Duplicate Rows but Keep One (4 Methods)
Delete duplicate rows in Oracle but keep one, using MIN(ROWID), ROW_NUMBER and GROUP BY, with expected output, NULL traps and how to prevent repeats.
ORA-01555 Snapshot Too Old in Oracle: Causes and Fixes
Fix ORA-01555 snapshot too old in Oracle: find the failing query, read V$UNDOSTAT, size undo correctly and stop committing inside cursor loops.
ORA-00060 Deadlock Detected in Oracle: Causes and Fixes
Why Oracle raises ORA-00060 deadlock detected, what it rolls back, how to read the trace file, and code fixes: lock order, FK indexes and retries.
Oracle Pagination Query: OFFSET FETCH vs ROWNUM (Examples)
Write an Oracle pagination query with OFFSET FETCH (12c+) or ROWNUM (11g), see each page's output, and learn keyset paging for fast deep pages.
Mutating Table Error in Oracle (ORA-04091): How to Fix It
Fix the mutating table error in Oracle (ORA-04091): see why row-level triggers fail, then solve it with a statement-level or compound trigger.
How to Read Explain Plan in Oracle (With Examples)
Learn how to read an explain plan in Oracle: execution order, Rows and Cost, access vs filter predicates, and real row counts with DBMS_XPLAN.
Oracle Blocking Sessions Query: Find and Fix Lock Waits
Find blocking sessions in Oracle with V$SESSION and V$LOCK, trace the root blocker and locked row, and resolve the block safely. With example output.
Oracle LISTAGG DISTINCT: Remove Duplicates (With Examples)
Remove duplicate values from Oracle LISTAGG with DISTINCT in 19c, or a subquery on 11g to 18c. Includes output, ordering tips and an ORA-01489 fix.
Oracle BULK COLLECT LIMIT Example with FORALL (Step by Step)
Learn Oracle BULK COLLECT with LIMIT step by step: the safe fetch loop, the %NOTFOUND trap, FORALL inserts and SAVE EXCEPTIONS, with expected output.
Oracle MERGE Statement Example: Upsert, Update and Delete
Learn the Oracle MERGE statement with examples: upsert, conditional update, DELETE WHERE, single-row upsert, and fixes for ORA-30926 and ORA-38104.
Mastering Oracle Database Architecture: A Comprehensive Overview
Ever wondered what happens behind the scenes when you hit “Execute” on a SQL query? It’s not just magic; it’s a sophisticated symphony of memory structures, specialized background processes, and a meticulously organized physical storage hierarchy. This intricate system is what allows Oracle to handle petabytes of data, ensure high concurrency, and guarantee rock-solid data
Understanding Oracle Triggers – A Comprehensive Guide with Examples
In the world of database management, ensuring data consistency, integrity, and automation is crucial. Oracle triggers are a powerful tool to accomplish these objectives. They allow the automatic execution of specified actions when certain database events occur.
Forward and Backward Navigation in Oracle PL/SQL- Expert Examples
Navigating through rows of data in Oracle PL/SQL is a common requirement when working with large datasets or developing applications that involve data traversal.
What are the Triggers in PLSQL? How do they work?
Triggers in PLSQL are implicitly executed when the defined event occurs, such as INSERT, UPDATE, or DELETE operations.
