Defalt_Column

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SQL> CREATE TABLE T_TEST_A(
2    NUM                 NUMBER(3,1) NOT NULL
3 , CHAR2               VARCHAR2(2) DEFAULT '1'
4 )
5 PCTFREE 15
6 TABLESPACE TYA
7 STORAGE (
8    INITIAL 1000
9    NEXT    1000
10    PCTINCREASE 0
11 );
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-- DEFAULT�A��g蠅�L�A�j�A�A�A�n�A�A�P猝��"NUM"�A�q�A�^�A�A�e�w�A�J�j�L�A�J�A�P
SQL> INSERT INTO T_TEST_A (NUM) VALUES (11);
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SQL> SELECT * FROM T_TEST_A;
      NUM CH
--------- --                                                                        11 1      -- DEFAULT�A��g蠅�L�A�\�P猝��A�q�A眞�w�A��j�}�A�I�A譴�j�A�A�A�J�A�P
SQL>
SQL> ALTER TABLE T_TEST_A ADD (YMD DATE DEFAULT SYSDATE );
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SQL> SELECT * FROM T_TEST_A;
      NUM CH YMD
--------- -- ----------------                                                       11 1 00-09-05
-- DEFAULT�A�K�g蠅�L�A�j�A�A�A觜猝��A�P�\�L�A�L�A�J�A�P

SQL> UPDATE T_TEST_A SET CHAR2 = '2';
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SQL> SELECT * FROM T_TEST_A;
      NUM CH YMD
--------- -- ----------------
       11 2 00-09-05
-- �V�B�A�qNULL�e�w�A�k�P�P�\�L�A�L�A�j�A�K�A�J�A�P
SQL> UPDATE T_TEST_A SET CHAR2 = NULL;
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SQL> SELECT * FROM T_TEST_A;
      NUM CH YMD
--------- -- ----------------
       11    00-09-05
-- �R鄒��A�I�A譴�\�E�j�B�V�E��E襪�z�P�X�c�A�A�H�A襪�lDEFAULT�A��g蠅�L�A�\�P猝��A��
-- NULL�A�P�P猝��A�k�A�u�A襪�E�A�l�A��n��A�H�A蠅�J�A�P
SQL> DESC T_TEST_A;
�t�Z�`�[                            Null?    �E�k�B�V�E�\�L�\
------------------------------- -------- -----------
NUM                             NOT NULL NUMBER(3,1)
CHAR2                                    VARCHAR2(2)
YMD                                      DATE

-- MODIFY�A�k�A盪�l�A�B�A�J�A�P

SQL> CREATE TABLE T_TEST_A(
2    NUM                 NUMBER(3,1) NOT NULL
3 , CHAR2               VARCHAR2(2) NULL
4 )
5 PCTFREE 15
6 TABLESPACE TYA
7 STORAGE (
8    INITIAL 1000
9    NEXT    1000
10    PCTINCREASE 0
11 );
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SQL>
SQL> ALTER TABLE T_TEST_A MODIFY CHAR2 VARCHAR2(2) DEFAULT '1';
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