记录锁定问题

[arclala]

在读取表的某一行记录时，锁定这一行，直到我更新了这行的记录后再解锁，不知怎样实现？

[hrb_qiuyb]

select ... for update;

[lianhg]

Dim objRe As New ADODB.Recordset
objRe.Open "select fld from tbl", , , adLockPessimistic

[beckhambobo]

DECLARE
-- Number of credits to add to each student's total
v_NumCredits classes.num_credits%TYPE;

-- This cursor will select only those students who are currently
-- registered for HIS 101.
CURSOR c_RegisteredStudents IS
SELECT *
FROM students
WHERE id IN (SELECT student_id
FROM registered_students
WHERE department= 'HIS'
AND course = 101)
FOR UPDATE OF current_credits;

BEGIN
-- Set up the cursor fetch loop.
FOR v_StudentInfo IN c_RegisteredStudents LOOP
-- Determine the number of credits for HIS 101.
SELECT num_credits
INTO v_NumCredits
FROM classes
WHERE department = 'HIS'
AND course = 101;

-- Update the row we just retrieved from the cursor.
UPDATE students
SET current_credits = current_credits + v_NumCredits
WHERE CURRENT OF c_RegisteredStudents;
END LOOP;

-- Commit our work, and release the lock.
COMMIT;
END;
/

注意：在commit前，把所有dml语句操作，遇到事务处理就马上释放任何锁