CSC-131beginner

SQL: Core Concepts

SQL is a declarative language for defining, querying, and modifying relational data. SQL supports application backends, reports, analytics, migrations, data cleaning, administration, ETL, and nearly any workflow using relational databases.

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SQL: Core Concepts

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Prerequisites

CSC-130Relational Databases: Systems, Limits & Advanced Connections→

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CSC-132SQL: Components & Representation→

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SQL is a declarative language for defining, querying, and modifying relational data.

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A SQL engine parses a statement, resolves names and types, rewrites where needed, builds candidate plans, estimates costs using statistics, executes the selected plan, and returns or modifies rows under transaction rules.

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EXPLAIN output shows chosen plans, while indexes and statistics can change those plans without changing query meaning.