I have a SELECT statement, and I want to DELETE what I am selecting. When I change the SELECT to a DELETE, I get errors. How do I use the DELETE to delete what I selected?
This is my query:
SELECT course.course_id FROM course LEFT JOIN section ON section.course_id = course.course_id WHERE section.course_id IS NULL; The DELETE keyword is used to delete an entire record. If I understand you correctly you are taking a SELECT {column} and trying to delete that column. If you want to clear the value in that specific cell use an UPDATE query.
update
I tried recreating your model course table
course_id course_name 1 First Course 2 Second Course 3 Third Course section table
section_id course_id section_name 1 1 First Section 2 1 Second Section 3 3 Third Section the delete query I used was
DELETE FROM course WHERE course.course_id NOT IN( SELECT section.course_id FROM section ); 
You need to use the delete keyword. The syntax for this is usually along the lines of:
delete from table_name where ... The ... in my example should match exactly what you have in your select statement.
You can find more info on this in my MySQL docs.
The DELETE statement has a WHERE clause. Use the WHERE clause of the SELECT statement as the WHERE clause for the DELETE statement.
for instance:
SELECT name FROM table WHERE id = 1; will have the following as its delete
DELETE FROM table WHERE id = 1; in case your select has no WHERE clause;
SELECT name FROM table; the statement becomes:
DELETE FROM table; The WHERE clause of the SELECT statement is the same as the WHERE clause for the DELETE statement.
NB: The second example will require that safe mode is disabled.
DELETE table WHERE .... Ensure that you're not doing something likeDELETE * FROM table WHERE ...