{"id":1483,"date":"2016-07-06T22:37:06","date_gmt":"2016-07-06T14:37:06","guid":{"rendered":"https:\/\/yangtingkun.net\/?p=1483"},"modified":"2016-07-06T22:37:06","modified_gmt":"2016-07-06T14:37:06","slug":"%e9%9d%9e%e7%a9%ba%e5%ad%97%e6%ae%b5%e7%a9%ba%e5%80%bc%e7%9a%84%e4%ba%a7%e7%94%9f","status":"publish","type":"post","link":"https:\/\/yangtingkun.net\/?p=1483","title":{"rendered":"\u975e\u7a7a\u5b57\u6bb5\u7a7a\u503c\u7684\u4ea7\u751f"},"content":{"rendered":"

\u4e0a\u4e00\u7bc7\u8ba8\u8bba\u4e86\u975e\u7a7a\u5b57\u6bb5\u4e2d\u5982\u679c\u5b58\u5728\u7a7a\u503c\u5bf9\u4e8e\u67e5\u8be2\u7684\u5f71\u54cd\uff0c\u8fd9\u91cc\u63cf\u8ff0\u4e00\u4e0b\u5bfc\u81f4\u95ee\u9898\u7684\u539f\u56e0\u3002
\n\u975e\u7a7a\u5b57\u6bb5\u7a7a\u503c\u5bf9\u67e5\u8be2\u7684\u5f71\u54cd\uff1ahttps:\/\/yangtingkun.net\/?p=1481<\/a>
\n\u4e66\u63a5\u4e0a\u6587\uff0c\u5176\u5b9eCBO\u7684\u5224\u65ad\u672c\u8eab\u662f\u6ca1\u6709\u95ee\u9898\u7684\uff0c\u95ee\u9898\u5728\u4e8e\uff0c\u4e3a\u4ec0\u4e48\u4e00\u4e2a\u7a7a\u503c\u4f1a\u5b58\u5728\u975e\u7a7a\u7ea6\u675f\u7684\u5b57\u6bb5\u4e2d\u3002
\n\u91cd\u65b0\u770b\u4e00\u4e0b\u95ee\u9898\uff1a
\nSQL> select * from t_def;
\n ID NAME TYPE
\n---------- ------------------------------ --------
\n 1 a
\nSQL> select * from t_def where type is null;
\nno rows selected
\nSQL> select * from t_def where type is not null;
\n ID NAME TYPE
\n---------- ------------------------------ --------
\n 1 a
\nSQL> select dump(type) from t_def;
\nDUMP(TYPE)
\n--------------------------------------------
\nNULL
\nSQL> select nvl(type, 'is null') from t_def;
\nNVL(TYPE
\n--------
\nis null
\nSQL> select dbms_metadata.get_ddl('TABLE', 'T_DEF') from dual;
\nDBMS_METADATA.GET_DDL('TABLE','T_DEF')
\n--------------------------------------------------------------------------------
\n CREATE TABLE \"TEST\".\"T_DEF\"
\n ( \"ID\" NUMBER,
\n \"NAME\" VARCHAR2(8) DEFAULT 'a',
\n \"TYPE\" VARCHAR2(8) DEFAULT '' NOT NULL ENABLE
\n ) SEGMENT CREATION IMMEDIATE
\n PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
\n NOCOMPRESS LOGGING
\n STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
\n PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
\n BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
\n TABLESPACE \"USERS\"<\/code>
\n\u4e4b\u524d\u63d0\u5230\uff0c\u7531\u4e8eTYPE\u5217\u5177\u6709\u975e\u7a7a\u7ea6\u675f\uff0c\u5bfc\u81f4CBO\u7ed9\u51fa\u7684\u6267\u884c\u8ba1\u5212\u8fd4\u56de\u4e86\u9519\u8bef\u7684\u7ed3\u679c\uff0c\u4f46\u662f\u95ee\u9898\u7684\u6839\u6e90\u5728\u4e8e\uff0c\u4e3aOracle\u4f1a\u5141\u8bb8\u7a7a\u503c\u63d2\u5165\u5230\u975e\u7a7a\u7ea6\u675f\u5b57\u6bb5\u4e2d\uff1a
\nSQL> insert into t_def (id, name) values (1, 'a');
\ninsert into t_def (id, name) values (1, 'a')
\n*
\nERROR at line 1:
\nORA-01400: cannot insert NULL into (\"TEST\".\"T_DEF\".\"TYPE\")<\/code>
\n\u90a3\u4e48\u662f\u4ec0\u4e48\u60c5\u51b5\u5bfc\u81f4\u4e86\u9519\u8bef\u7684\u6570\u636e\u7ed5\u8fc7\u4e86Oracle\u7684\u68c0\u67e5\u5462\u3002\u68c0\u67e5\u8868\u7684\u5b9a\u4e49\uff0c\u53d1\u73b0\u4e00\u4e2a\u7279\u522b\u4e4b\u5904\uff0cTYPE\u5217\u7684\u9ed8\u8ba4\u503c\u672c\u8eab\u5c31\u662fNULL\uff0c\u662f\u4e0d\u662f\u8fd9\u4e2a\u5bfc\u81f4\u4e86Oracle\u7684\u6570\u636e\u95ee\u9898\u5462\uff1a
\nSQL> CREATE TABLE T_TEST (ID NUMBER, NAME VARCHAR2(30) DEFAULT '' NOT NULL);
\n\u8868\u5df2\u521b\u5efa\u3002
\nSQL> INSERT INTO T_TEST (ID) VALUES (1);
\nINSERT INTO T_TEST (ID) VALUES (1)
\n*
\n\u7b2c 1 \u884c\u51fa\u73b0\u9519\u8bef:
\nORA-01400: \u65e0\u6cd5\u5c06 NULL \u63d2\u5165 (\"TEST\".\"T_TEST\".\"NAME\")<\/code>
\n\u663e\u7136\u95ee\u9898\u6ca1\u6709\u90a3\u4e48\u7b80\u5355\uff0c\u867d\u7136\u9ed8\u8ba4\u503c\u4eba\u4e3a\u8bbe\u7f6e\u4e3aNULL\u5e76\u4e0d\u5e38\u89c1\uff0c\u4f46\u662f\u5bf9\u4e8e\u54ea\u4e9b\u5177\u6709NOT NULL\u7ea6\u675f\u4e14\u6ca1\u6709\u6307\u5b9a\u9ed8\u8ba4\u503c\u7684\u5217\uff0c\u90fd\u76f8\u5f53\u4e8e\u9ed8\u8ba4\u503c\u4e3aNULL\u3002\u663e\u7136\u4e0d\u592a\u53ef\u80fd\u662f\u5e38\u89c4\u95ee\u9898\u5bfc\u81f4\u7684bug\uff0cOracle\u7ecf\u8fc7\u8fd9\u4e48\u591a\u5e74\u8fd9\u4e48\u591a\u7248\u672c\u7684\u78e8\u7ec3\uff0c\u5e94\u8be5\u4e0d\u4f1a\u572811g\u8fd8\u51fa\u73b0\u8fd9\u79cd\u95ee\u9898\uff0c\u800c\u4e14\u8fd9\u4e2a\u95ee\u9898\u8fd8\u662f\u7b2c\u4e00\u6b21\u78b0\u5230\u3002\u7efc\u4e0a\u6240\u8ff0\uff0c\u63a8\u65ad\u95ee\u9898\u53ef\u80fd\u662f11g\u65b0\u7279\u6027\u6240\u5f15\u5165\u7684bug\u3002
\n\u5206\u6790\u5230\u8fd9\u91cc\uff0c\u95ee\u9898\u7684\u7b54\u6848\u4e5f\u547c\u4e4b\u6b32\u51fa\u4e86\uff0c\u6ca1\u9519\uff0c\u5bfc\u81f4\u95ee\u9898\u7684\u5c31\u662f11g\u65b0\u589e\u7684\u5feb\u901f\u6dfb\u52a0\u975e\u7a7a\u9ed8\u8ba4\u503c\u7684\u529f\u80fd\uff0c\u8fd9\u4e2a\u8be1\u5f02\u7684\u95ee\u9898\u53ef\u4ee5\u901a\u8fc7\u4e0b\u9762\u7684\u4e09\u6b65\u7b80\u5355\u7684\u91cd\u65b0\uff1a
\nSQL> create table t_def (id number, name varchar2(30) default '' not null);
\nTable created.
\nSQL> insert into t_def values (1, 'a');
\n1 row created.
\nSQL> alter table t_def add type varchar2(8) default '' not null;
\nTable altered.
\nSQL> select * from t_def;
\n ID NAME TYPE
\n---------- ------------------------------ --------
\n 1 a<\/code>
\nOracle\u786e\u5b9e\u5141\u8bb8NOT NULL\u5217\u7684\u9ed8\u8ba4\u503c\u4e3aNULL\uff0c\u5982\u679c\u4e0d\u6307\u5b9a\u9ed8\u8ba4\u503c\u90a3\u4e48\u5c31\u76f8\u5f53\u4e8e\u9ed8\u8ba4\u503c\u4e3aNULL\uff0c\u4f46\u662f\u5bf9\u4e8e11g\u65b0\u589e\u7684\u65b0\u7279\u6027\u800c\u8a00\uff0cDEFAULT\u4e3aNULL\u662f\u8981\u7981\u6b62\u7684\uff0c\u5426\u5219\u5c31\u4f1a\u5bfc\u81f4\u73b0\u6709\u8bb0\u5f55\u7684NOT NULL\u5b57\u6bb5\u51fa\u73b0NULL\u503c\u3002
\n\u800c\u4e14\u7531\u4e8e\u6307\u5b9a\u7684DEFAULT\u662fNULL\uff0cECOL$\u4e2d\u5c45\u7136\u6ca1\u6709\u8bb0\u5f55\u4efb\u4f55\u4fe1\u606f\uff1a
\nSQL> select * from sys.ecol$;
\nno rows selected<\/code>
\n\u770b\u6765\u4efb\u4f55\u65b0\u7279\u6027\u90fd\u96be\u4ee5\u907f\u514dBUG\u7684\u4ea7\u751f\uff0c\u6ca1\u60f3\u5230\u4e00\u4e2a\u589e\u52a0\u975e\u7a7a\u9ed8\u8ba4\u503c\u7684\u65b0\u7279\u6027\u4e5f\u4f1a\u5f15\u53d1BUG\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\u4e0a\u4e00\u7bc7\u8ba8\u8bba\u4e86\u975e\u7a7a\u5b57\u6bb5\u4e2d\u5982\u679c\u5b58\u5728\u7a7a\u503c\u5bf9\u4e8e\u67e5\u8be2\u7684\u5f71\u54cd\uff0c\u8fd9\u91cc\u63cf\u8ff0\u4e00\u4e0b\u5bfc\u81f4\u95ee\u9898\u7684\u539f\u56e0\u3002 \u975e\u7a7a\u5b57\u6bb5\u7a7a\u503c\u5bf9\u67e5\u8be2\u7684\u5f71\u54cd\uff1ahttps:\/\/yangtingkun.net\/?p=1481 \u4e66\u63a5\u4e0a\u6587\uff0c\u5176\u5b9eCBO\u7684\u5224\u65ad\u672c\u8eab\u662f\u6ca1\u6709\u95ee\u9898\u7684\uff0c\u95ee\u9898\u5728\u4e8e\uff0c\u4e3a\u4ec0\u4e48\u4e00\u4e2a\u7a7a\u503c\u4f1a\u5b58\u5728\u975e\u7a7a\u7ea6\u675f\u7684\u5b57\u6bb5\u4e2d\u3002 \u91cd\u65b0\u770b\u4e00\u4e0b\u95ee\u9898\uff1a SQL> select * from t_def; ID NAME TYPE ———- —————————— ——– 1 a SQL> select * from t_def where type is null; no rows selected SQL> select * from t_def where type is not null; ID … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[5,3],"tags":[558,1288,1165],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2yiY3-nV","_links":{"self":[{"href":"https:\/\/yangtingkun.net\/index.php?rest_route=\/wp\/v2\/posts\/1483"}],"collection":[{"href":"https:\/\/yangtingkun.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/yangtingkun.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/yangtingkun.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/yangtingkun.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1483"}],"version-history":[{"count":1,"href":"https:\/\/yangtingkun.net\/index.php?rest_route=\/wp\/v2\/posts\/1483\/revisions"}],"predecessor-version":[{"id":1484,"href":"https:\/\/yangtingkun.net\/index.php?rest_route=\/wp\/v2\/posts\/1483\/revisions\/1484"}],"wp:attachment":[{"href":"https:\/\/yangtingkun.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1483"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/yangtingkun.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1483"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/yangtingkun.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1483"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}