<\/span><\/h3>\n\n\n\n\u6539\u5199\u6210\u9002\u5408\u6570\u5b57\u7684\u5199\u6cd5
decode(A,XX,XX,YY,XX,'')=XX
\u4e5f\u5c31\u662f\u628aYY\u503c\u6539\u6210XX,\u53d8\u6210\u90fd\u5224\u65ad\u7b49\u503cXX<\/p>\n\n\n\n
\u6539\u6210case\u7684\u5199\u6cd5\uff0c\u9002\u5408\u5b57\u7b26<\/p>\n\n\n\n
case A when XX then XX when YY then XX end)=XX<\/code><\/pre>\n\n\n\ngbase> select * from t3 where id=1 or id=11;\n+------+------+\n| id | id2 |\n+------+------+\n| 1 | 1 |\n| 11 | 11 |\n+------+------+\n2 rows in set (Elapsed: 00:00:00.07)\n\ngbase> select * from t3 where decode(id,1,1,11,1)=1;\n+------+------+\n| id | id2 |\n+------+------+\n| 1 | 1 |\n| 11 | 11 |\n+------+------+\n2 rows in set (Elapsed: 00:00:00.08)<\/code><\/pre>\n\n\n\n<\/span>A=XX OR B=YY or C=ZZ<\/span><\/h3>\n\n\n\n\u6539\u5199\u6210<\/p>\n\n\n\n
concat(case when a=XX then XX else '' end,case when B=YY then XX else '' end,case when C=ZZ then XX else '' end) like 'XX%'<\/code><\/pre>\n\n\n\n\u5176\u4e2d\u7684XX,YY\u53ef\u4ee5\u662f\u76f8\u540c\u503c\u6216\u8005\u4e0d\u540c\u503c\u3002 \u6838\u5fc3\u4e5f\u662f\u5c06\u591a\u4e2aOR\u5224\u65ad\uff0c\u6539\u62101\u4e2a\u5224\u65ad\u3002<\/p>\n\n\n\n
gbase> select * from t3 where id=111 or id2=9999;\n+------+------+\n| id | id2 |\n+------+------+\n| 111 | 1111 |\n+------+------+\n1 row in set (Elapsed: 00:00:00.04)\n\ngbase> select * from t3 where concat(case when id=111 then 111 else '' end,case when id2=9999 then 111 else '' end) like '111%';\n+------+------+\n| id | id2 |\n+------+------+\n| 111 | 1111 |\n+------+------+\n1 row in set (Elapsed: 00:00:00.09)<\/code><\/pre>\n\n\n\n<\/span>JOIN\u6761\u4ef6 \u8981\u6c42\u7ed3\u679c\u96c6\u6ca1\u6709\u81a8\u80c0<\/span><\/h2>\n\n\n\n\u5982\u4e0b\u7684JOIN\u91cc\uff0cOR\u6761\u4ef6<\/p>\n\n\n\n
select b.XX from a \nleft join b on (a.id=b.id or a.name=b.name) and ...\u5176\u5b83join\u6761\u4ef6<\/code><\/pre>\n\n\n\n\u6539\u5199\u62102\u4e2ajoin<\/p>\n\n\n\n
select coalesce(b.XX,b2.XX) from a\nleft join b on a.id=b.id and \u2026\u5176\u5b83join\u6761\u4ef6\nleft join b b2 on a.id<>b2.id and a.name=b2.name and \u2026\u5176\u5b83join\u6761\u4ef6<\/code><\/pre>\n\n\n\n\u8981\u6c42\u7ed3\u679c\u96c6\u6ca1\u6709\u81a8\u80c0\uff0c\u6bd4\u5982a\u88681\u4e07\u884c\uff0c\u7ed3\u679c\u96c6\u4f9d\u7136\u662f\u5de6\u8868\u76841\u4e07\u884c\u3002\u4e5f\u5c31\u662f1\u5bf91\u7684\u573a\u666f\uff0c\u53f3\u8868\u4e0d\u80fd\u51fa\u73b0\u91cd\u590d\u503c\uff0c\u5bfc\u81f4\u5de6\u8868\u81a8\u80c0\u3002
\u5426\u5219\u56e0\u5de6\u8868\u51fa\u73b0\u91cd\u590d\uff0c1\uff1an\uff0c\u5bfc\u81f4\u6539\u5199\u540e\u7684\u65b9\u6848\u7ed3\u679c\u96c6\u884c\u6570\u5c11\u4e86\u3002<\/p>\n\n\n\n
\u800cselect\u90e8\u5206\u7528\u5230b\u8868\u7684\u5217\uff0c\u9700\u8981\u6839\u636eb\u548cb2\u7684\u5217\u8fdb\u884c\u9009\u62e9,\u6bd4\u5982b.XX \u53d8\u6210 coalesce(b.XX,b2.XX)<\/p>\n\n\n\n
gbase> select * from t1;\n+------+------+\n| id | id2 |\n+------+------+\n| 1 | 66 |\n| 2 | 77 |\n+------+------+\n2 rows in set (Elapsed: 00:00:00.06)\n\ngbase> select * from t3;\n+------+------+\n| id | id2 |\n+------+------+\n| 1 | 66 |\n| 3 | 77 |\n| 9 | 99 |\n+------+------+\n3 rows in set (Elapsed: 00:00:00.09)\n\ngbase> select * from t1 left join t3 on t1.id=t3.id or t1.id2=t3.id2;\n+------+------+------+------+\n| id | id2 | id | id2 |\n+------+------+------+------+\n| 1 | 66 | 1 | 66 |\n| 2 | 77 | 3 | 77 |\n+------+------+------+------+\n2 rows in set (Elapsed: 00:00:00.28)\n\ngbase> select * from t1 left join t3 on t1.id=t3.id left join t3 t3_2 on t1.id<>t3_2.id and t1.id2=t3_2.id2;\n+------+------+------+------+------+------+\n| id | id2 | id | id2 | id | id2 |\n+------+------+------+------+------+------+\n| 2 | 77 | NULL | NULL | 3 | 77 |\n| 1 | 66 | 1 | 66 | NULL | NULL |\n+------+------+------+------+------+------+\n2 rows in set (Elapsed: 00:00:00.28)\n\ngbase> select t1.id,t1.id2,coalesce(t3.id,t3_2.id)id,coalesce(t3.id2,t3_2.id2)id2 from t1 left join t3 on t1.id=t3.id left join t3 t3_2 on t1.id<>t3_2.id and t1.id2=t3_2.id2;\n+------+------+------+------+\n| id | id2 | id | id2 |\n+------+------+------+------+\n| 2 | 77 | 3 | 77 |\n| 1 | 66 | 1 | 66 |\n+------+------+------+------+\n2 rows in set (Elapsed: 00:00:00.16)<\/code><\/pre>\n\n\n\n<\/span>Summary<\/span><\/h2>\n\n\n\n\u672c\u6587\u7684OR\u4f18\u5316\uff0c\u90fd\u8d8b\u5411\u4e8e\u624b\u5de5\u8c03\u6574\u6267\u884c\u8ba1\u5212\uff0c\u7279\u522b\u662f\u8fc7\u6ee4\u6761\u4ef6\u3002 \u800cJOIN\u7684OR\u4f18\u5316\uff0c\u5fc5\u987b\u4fdd\u8bc11\uff1a1\uff0c\u4e0d\u80fd\u662f1\uff1an\u3002\u5426\u5219\u7ed3\u679c\u96c6\u53ef\u80fd\u662f\u9519\u7684\u3002<\/p>","protected":false},"excerpt":{"rendered":"
\u4e1a\u52a1SQL\u4e2d\u5305\u542bOR, \u5982\u679c\u53d1\u73b0\u6027\u80fd\u5bf9\u6bd4\u6ca1\u6709\u8fd9\u4e2aOR\u4e0b\u964d\u6781\u5927\uff0c\u53ef\u4ee5\u8003\u8651\u672c\u6587\u4ecb\u7ecd\u7684OR\u4f18\u5316\u8bd5\u8bd5\u3002\u5305\u62ec\u5728\u8fc7\u6ee4\u6761\u4ef6\u91cc\u7684OR\u4ee5\u53caJOIN\u6761\u4ef6\u91cc\u7684OR\u4e24\u79cd\u60c5\u51b5\u3002<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-12749","post","type-post","status-publish","format-standard","hentry","category-gbase8a"],"_links":{"self":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/12749","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/comments?post=12749"}],"version-history":[{"count":6,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/12749\/revisions"}],"predecessor-version":[{"id":12757,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/12749\/revisions\/12757"}],"wp:attachment":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media?parent=12749"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/categories?post=12749"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/tags?post=12749"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}