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LOCK TABLE�ϥơ��֥��٥�Υ��å��ɬ�פǤ��ж��礹��å��ޤ��Ե��ޤ�� NOWAIT��ꤵ�줿��硢LOCK TABLE��оݤΥ��å��Ǥ��ޤ��Ե��ޤ�� ˳��Ǥ��ʤ��С��Υ��ޥ�ɤ��ߤ��顼��Ϥ��ޤ�� å��ϡ��ټ��ȸ��ԤΥȥ�󥶥��󤬴�λ��ޤ��ݻ��ޤ�� (UNLOCK TABLE�Ȥ��ä��ޥ�ɤϤ��ޤ�� å��ϥȥ�󥶥��ν�λ��˾�˲��ޤ��)

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��ꥢ�饤��֥��Υ��٥�ǤΥȥ�󥶥��¹��ˤ��Ʊ�ͤθ��̤��ˤϡ��Ƥ�SELECTʸ�ȥǡ��Ѥ�ʸ��¹Ԥ��LOCK TABLEʸ��¹Ԥ��ɬ�פ��ޤ�� ꥢ�饤��֥�ʥȥ�󥶥��¦��黲�Ȥ��ǡ��ξ��֤ϡ��ǽ��SELECTʸ�ޤ��ϥǡ��ʸ��Ϥ��줿��Ǹ��ꤵ��ޤ�� ȥ�󥶥��Ǹ��LOCK TABLE��ԤäƤ�Ʊ��񤭹��ߤ��ɤ��ޤ��ȥ�󥶥��ɤ߹��оݤΥǡ��ߥåȤ��줿�ǿ��ͤ��б��Ƥ��뤫��ݾڤ��ޤ��

��Τ褦�ʥȥ�󥶥��ǥơ��֥��ǡ��ѹ��ϡ�SHARE�⡼�ɤǤϤʤ�SHARE ROW EXCLUSIVE��å��⡼�ɤ��Ѥ��ɬ�פ��ޤ�� ˤ�äơ��μ�Υȥ�󥶥��Ʊ��ʣ��¹Ԥ��뤳�Ȥ��ʤ��ʤ�ޤ�� SHARE ROW EXCLUSIVE��Ѥ��ʤ��ȡ��ǥåɥ��å��ȯ��ǽ��ޤ�� Ĥޤꡢ2�ĤΥȥ�󥶥��ξ��SHARE�⡼�ɤ��ΤΡ��ºݤ˹��Ԥ��ROW EXCLUSIVE�⡼�ɤ��뤳�Ȥ��Ǥ��ʤ��褦�ʾ��֤ˤʤ��ǽ��ޤ�� (�ȥ�󥶥��󼫿ȤΥ��å��϶��礷�ʤ��Τǡ��ȥ�󥶥��SHARE�⡼�ɤ��ݻ��Ƥ��ROW EXCLUSIVE��뤳�Ȥ��Ǥ��ޤ�� ¾�Υȥ�󥶥��SHARE�⡼�ɤ��ݻ��Ƥ��ˤ�ROW EXCLUSIVE��뤳�ȤϤǤ��ޤ��) �ǥåɥ��å��򤹤뤿��ˡ��μ¤��ƤΥȥ�󥶥��Ʊ�쥪�֥��Ȥ��Ф��Ʊ��ν��֤ǥ��å��Ƥ�� ޤ��1�ĤΥ��֥��Ȥ��Ф��ʣ��Υ��å��⡼�ɤ�ƤӽФ��硢�ȥ�󥶥��Ͼ�˺Ǥ��¤ζ��⡼�ɤ�ǽ�˼��ʤ��Фʤ�ޤ��

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LOCK TABLE ... IN ACCESS SHARE MODE�ˤϡ��оݥơ��֥��SELECT��¤�ɬ�פǤ�� ¾�η��LOCK�ˤϡ�UPDATE��DELETE��뤤�Ϥ��ξ��θ��¤�ɬ�פǤ��

LOCK TABLE�ϥȥ�󥶥��֥��å��(BEGIN/COMMIT��ȹ礻)�ǤΤ�ͭ��Ǥ�� äơ��ȥ�󥶥��󤬽�λ��ȥ��å��ޤ�� ȥ�󥶥��֥��å��γ��LOCK TABLE��ޥ�ɤϤ��Υ��ޥ�ɤΤߤΥȥ�󥶥��ޤ��Τǡ��Υ��å��ϼ��夹��˺��ޤ��

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BEGIN WORK;
LOCK TABLE films IN SHARE MODE;
SELECT id FROM films 
    WHERE name = 'Star Wars: Episode I - The Phantom Menace';
-- �쥳���ɤ��ʤ����ROLLBACK���Ƥ���������
INSERT INTO films_user_comments VALUES 
    (_id_, 'GREAT! I was waiting for it for so long!');
COMMIT WORK;

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BEGIN WORK;
LOCK TABLE films IN SHARE ROW EXCLUSIVE MODE;
DELETE FROM films_user_comments WHERE id IN
    (SELECT id FROM films WHERE rating < 5);
DELETE FROM films WHERE rating < 5;
COMMIT WORK;

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