pl_sql中的游标操作（Cursor operations in pl_sql）.doc

pl_sql中的游标操作（Cursor operations in pl_sql） / * Cursor (pointer, pointer to the head of the result set) In pl/SQL, it is used to traverse the result set of a multi-row record The cursor moves one way and does not remove the boundary. If it has moved to the end of the result set, the cursor always points to the last record Classification of cursors Explicit cursor Implicit cursor Dynamic cursors * / / * Explicit cursor (the select query corresponding to the cursor is fixed) define Cursor cursor name is query statement; (read only cursor) The cursor begins with cur_ Your cursor 1. Open cursor name; 2. Loop loop (loop, while, for) Get the data from the cursor The fetch directive moves the pointer down to get a row of data pointing to the current pointer Fetch cursor name into variable; The cursor has 4 commonly used properties (with initialization value false false 0 false) (read-only property) % FOUND - TRUE % NOTFOUND - when the % NOTFOUND attribute of the cursor is TRUE, the result set that the current cursor points to is in the tail % ROWCOUNT - the number of rows represented by the % ROWCOUNT of the cursor (the number of rows moved by the cursor) The % ISOPEN - cursor is open, always FALSE Remember to close the cursor after use Close cursor name; * / - iterate over all the employee information in the emp table declare Define explicit cursors Cursor cur_emp is select * from emp; V_emp emp % rowtype; The begin The open cur_emp; -- iterate over the cursor - loop cycle / * loop The fetch cur_emp into v_emp; Exit the when cur_emp % notfound; -- write business code Dbms_output. Put_line ( serial number: | | cur_emp % rowcount | | employee number: | | v_emp. Empno | |, employee name: | | v_emp, ename | |, engaged in position: | | v_emp. The job); End loop; * / Dbms_output. Put_line (cur_emp % rowcount); If cur_emp % notfound then Dbms_output. Put_line ( true ); The else Dbms_output. Put_line ( false ); End the if; If cur_emp % found then Dbms_output. Put_line ( true ); The