Joins

A join is a way of combining columns from one on more tables, using a condition that links the tables.

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SQL: Compare Two Tables for Differences in Data

How to compare two tables that share the same structure, to identify data differences between the two tables: missing rows, extra rows, or mismatch in attribute values.

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INNER JOIN and OUTER JOIN Explained

Overview of INNER JOIN and OUTER JOIN in Oracle, with examples, memory aids and a further drilldown of INNER JOIN and OUTER JOIN types.

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DISTINCT and How NOT To Use It

Oracle keyword DISTINCT restricts the result to unique rows from a query, but DISTINCT is often used as a quick fix to bad queries. Some practices to avoid when using DISTINCT.

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Scalar Subquery: SELECT within SELECT!

A scalar subquery is a single row, single column query, which looks just like a column or function in the SELECT clause. Here’s a look at the unique characteristics and benefits of this feature in Oracle.

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