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SQL - Coggle Diagram
SQL
Main SQL Commands
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CREATE → Creates tables, views, indexes, or objects.
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CONSTRAINT → Defines constraints (primary keys, foreign keys, integrity).
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Database modifications
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ALTER TABLE → Modifies structure (columns, types, constraints).
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NULL values
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Comparison
NULL is not equal to anything, not even to another NULL.
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Effect
Comparisons, calculations, and aggregation functions are affected.
Views
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Possible operations:
SELECT, INSERT, UPDATE, DELETE (if they are simple)
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Set Operations
UNION → Combines query results, eliminating duplicates.
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UNION ALL → Combines results, including duplicates.
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Embedded SQL
Integrating SQL within programming languages (Java, C#, PHP, Python, etc.)
Main Functions
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Execution of queries (SELECT, INSERT, UPDATE, DELETE).
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Nested subqueries
Queries within other queries (in WHERE, HAVING, or SELECT).
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