Database Systems, unit: SQL Fundamentals. Core concepts, terminology, and worked-example cues a college student meets for this unit, building on prior units without repeating them. Front: a term, concept, or short problem cue. Back: the definition, explanation, or answer.
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- What is SQL?
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Structured Query Language, used to define, manipulate, and query relational databases- What does the SELECT statement do?
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Retrieves data from one or more tables- What does the WHERE clause do?
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Filters rows based on a specified condition- What does the INSERT statement do?
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Adds new rows of data into a table- What does the UPDATE statement do?
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Modifies existing data in a table- What does the DELETE statement do?
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Removes rows from a table- What does the CREATE TABLE statement do?
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Defines a new table and its columns- What is a JOIN used for?
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Combining rows from two or more tables based on a related column- What is an INNER JOIN?
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A join that returns only rows with matching values in both tables- What is a LEFT JOIN?
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A join that returns all rows from the left table, with matches from the right table or nulls- What does the GROUP BY clause do?
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Groups rows sharing a value into summary rows- What does the ORDER BY clause do?
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Sorts the result set by one or more columns- What is an aggregate function?
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A function that performs a calculation on multiple rows, such as COUNT, SUM, or AVG- What does the HAVING clause do?
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Filters groups after aggregation, similar to WHERE for individual rows- What is a subquery?
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A query nested inside another query
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