База данных: MySQL
DECLARE cursor_name CURSOR FOR select_statement
This statement declares a cursor and associates it with a SELECT
statement that retrieves the rows to be traversed by the cursor. To
fetch the rows later, use a FETCH statement. The number of columns
retrieved by the SELECT statement must match the number of output
variables specified in the FETCH statement.
The SELECT statement cannot have an INTO clause.
Cursor declarations must appear before handler declarations and after
variable and condition declarations.
A stored program may contain multiple cursor declarations, but each
cursor declared in a given block must have a unique name. For an
example, see https://dev.mysql.com/doc/refman/8.0/en/cursors.html.
For information available through SHOW statements, it is possible in
many cases to obtain equivalent information by using a cursor with an