correlated subqueries

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SQL to Find Master Records with Identical Detail Records

SQL to find those records in the master table that have identical detail records in a child table.

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MERGE: Insert New Rows, Update Existing Rows in One Shot

MERGE in Oracle combines the power of INSERT and UPDATE into one power-packed statement

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Correlated Subquery

A correlated subquery is a type of nested subquery that uses columns from the outer query in its WHERE clause. While a simple subquery is evaluated only once for each table, a correlated subquery is evaluated once for each row.

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Understanding Subqueries and Their Types

A subquery – that is, a query within a query – can be of various flavors in Oracle. Subqueries may be simple or correlated, nested or scalar. A closer look at the types of subqueries and their purpose.

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