In this chapter, you learn what cursors are and how to use them.
As you have seen in previous chapters, MariaDB retrieval operations work with sets of rows known as result sets. The rows returned are all the rows that match a SQL statement—zero or more of them. Using simple
SELECT statements, there is no way to get the first row, the next row, or the previous ten rows, for example. Nor is there an easy way to process all rows, one at a time (as opposed to all of them in a batch).
Sometimes there is a need to step through rows forward or backward and one or more at a time. This is what cursors are used for. A cursor is a database query stored on the MariaDB server—not a
SELECT statement, but the result set ...