Oracle JOIN: Cross-Table Query Guide

Cross-table queries are typically done in Oracle databases using the JOIN operator in SQL statements. Here are some commonly used examples of cross-table queries:

1. INNER JOIN: Returns rows that have matching values in both tables.

SELECT table1.column1, table2.column2
FROM table1
INNER JOIN table2 ON table1.join_column = table2.join_column;

1. Left join: returns all rows from the left table, as well as any matching rows from the right table (if any).

SELECT table1.column1, table2.column2
FROM table1
LEFT JOIN table2 ON table1.join_column = table2.join_column;

1. RIGHT JOIN: Retrieves all rows from the right table and matching rows from the left table (if any).

SELECT table1.column1, table2.column2
FROM table1
RIGHT JOIN table2 ON table1.join_column = table2.join_column;

1. Full join: Returns all rows from both tables, regardless of whether there is a match.

SELECT table1.column1, table2.column2
FROM table1
FULL JOIN table2 ON table1.join_column = table2.join_column;

1. Cross join: returns all possible combinations of rows from two tables, without any conditions.

SELECT table1.column1, table2.column2
FROM table1
CROSS JOIN table2;

In addition to the examples above, other techniques such as subqueries, union queries, and intersect queries can be used in queries to perform cross-table searches. When writing cross-table queries, make sure to use appropriate conditions to join tables, and be careful in handling any potential duplicate rows or performance issues.