What are SQL constraints? Joins ? What are index and views? What are having and where clause difference?

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SQL constraints are rules that enforce data integrity, joins are used to combine data from multiple tables, indexes improve query performance, views are virtual tables, and having and where clauses filter data differently.

SQL constraints ensure data integrity by enforcing rules on columns (e.g. NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY).
Joins are used to combine data from multiple tables based on a related column (e.g. INNER JOIN, LEFT JOIN, RIGHT JOIN).
Indexes are data structures that improve query performance by allowing faster data retrieval (e.g. clustered, non-clustered).
Views are virtual tables that display data from one or more tables based on a predefined query.
The WHERE clause is used to filter rows based on a specified condition, while the HAVING clause is used to filter groups based on a specified condition (e.g. WHERE for individual rows, HAVING for groups).

What are SQL constraints? Joins ? What are index and views? What are having and where clause difference?

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