Which of the following SQL statements can be used to select all the records from a table named "Persons" where the "firstName" is "Joe"?

Question

BlackTom AI · Accepted Answer

Use the WHERE clause with an equality comparison to filter rows: SELECT * FROM Persons WHERE firstName='Joe';

1) Relevant knowledge points and concepts
- SELECT retrieves columns; * means all columns.
- FROM specifies the table (Persons).
- WHERE applies a condition to filter rows.
- String literals in SQL are written in single quotes (standard SQL). The equality operator = compares a column to a value. The LIKE operator is used for pattern matching (column LIKE 'pattern'), not as a replacement for WHERE.

2) Complete reasoning step by step
- We want all records (all columns) from the table Persons, so start with SELECT * FROM Persons.
- We need only rows where firstName is exactly "Joe", so append a WHERE clause comparing firstName to the string 'Joe' using =: WHERE firstName='Joe'.
- Combine parts: SELECT * FROM Persons WHERE firstName='Joe'; The trailing semicolon terminates the statement in many SQL environments.

3) Intermediate steps shown explicitly
- SELECT * → return every column.
- FROM Persons → use the table named Persons.
- WHERE firstName='Joe' → filter to rows whose firstName equals the string Joe.
- Full: SELECT * FROM Persons WHERE firstName='Joe';

4) Why the correct answer is correct
- It uses correct SQL clause order (SELECT … FROM … WHERE …), uses = for equality, and quotes the string literal correctly. This returns all rows from Persons where the firstName column exactly matches Joe.

5) Why the other options are incorrect
- "SELECT * FROM Persons WHERE firstName:'Joe';" uses a colon instead of the equality operator; that is invalid SQL syntax.
- "SELECT * FROM Persons LIKE 'Joe';" misplaces LIKE and omits the column; LIKE must be used as column LIKE 'pattern' and typically with wildcards (e.g., '%Joe%').
- "SELECT ALL FROM Persons and 'Joe';" is not valid SQL structure: SELECT ALL could be used but must be followed by column list and no trailing "and 'Joe'"; the condition is missing and syntax is wrong.

6) Conclusion
The correct SQL statement is SELECT * FROM Persons WHERE firstName='Joe'; which matches the provided answer.

Which of the following SQL statements can be used to select all the records from a table named "Persons" where the "firstName" is "Joe"?单项选择题

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