For a basic SQL query, what is the correct canonical ordering of clauses to retrieve filtered data from specific tables?
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ASELECT, FROM, WHERE
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BFROM, WHERE, SELECT
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CWHERE, FROM,SELECT
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DSELECT,WHERE,FROM
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EFROM, SELECT, WHERE
Answer
Correct Answer: SELECT, FROM, WHERE
Explanation
Introduction / Context:SQL statements follow a defined clause order. Although the logical processing order differs from the textual order, the written sequence for a standard SELECT statement must adhere to the SQL grammar to parse and execute correctly.
Given Data / Assumptions:
- The query is a simple SELECT (no GROUP BY, HAVING, ORDER BY).
- We want the correct written clause order for valid SQL syntax.
- Standard SQL conventions apply across engines.
Concept / Approach:The canonical written order begins with SELECT (what columns or expressions), then FROM (which tables or joins), followed by WHERE (row-level filters). Additional clauses like GROUP BY, HAVING, and ORDER BY come later when needed.
Step-by-Step Solution:
Identify the clauses to include: SELECT, FROM, WHERE.Recall the grammatical order: SELECT → FROM → WHERE.Select the option that matches this sequence.Verification / Alternative check:Test with: SELECT col FROM tab WHERE col > 0; The statement parses in all major RDBMSs.
Why Other Options Are Wrong:
- Orders beginning with FROM or WHERE violate SQL grammar.
- SELECT,WHERE,FROM misplaces the FROM clause and will not compile.
Common Pitfalls:Confusing written clause order with logical evaluation (FROM/WHERE logically precede SELECT). Despite that, the required written order starts with SELECT.
Final Answer:SELECT, FROM, WHERE