Choosing columns

SELECT * returns every column. Usually you want only a few. Instead of *, list the columns you want, separated by commas:

SELECT name, score FROM student;

The result has just those columns, in the order you wrote them.

You can rename a column in the result with AS. This does not change the table — only the heading shown:

SELECT name AS pupil, score AS mark FROM student;

The headings become pupil and mark. This is handy for clear reports.

Question. The table student has the fields id, name, form and score. Write a query that shows each student's form, then their name.

Answer. Name the two fields in the order the question asks for:

SELECT form, name FROM student;

form | name
11A  | Mei
11B  | Jamal
11A  | Sara
11B  | Tom
11A  | Lin

Writing SELECT name, form would show the same data with the columns the other way round, and the question asked for form first.

• A missing comma renames a column. SELECT name score FROM student is read as name AS score: you get one column headed score that holds the names. Put a comma between every two columns.
• No comma after the last column. SELECT name, score, FROM student is a syntax error.
• AS changes only the heading in the result. The table itself keeps its field names.