dating anzeigen - Updating fields in sql

The two hyphens in front of a line indicate that the line is a comment and the text will be ignored by the compiler.

In this case, the comment describes a permissible variation of the syntax.

So because of a bug there were a bunch of Question IDs set to NULL, but the Question ID of a related Answer ID is in the Answers table.

So say Question ID is NULL and Answer ID is 500, if we go to the Answers table and find Answer ID 500 there is a column with the Question ID that should have been where the NULL value is.

Adding a WHERE clause would limit the result set of the JOINed table as well.