<\/span><\/h2>\n\n\n\nFirst_value(XXX) OVER([PARTITION BY col_name1,col_name2,\u2026] ORDER BY col_name1 [asc\/desc], col_name2 [asc\/desc],\u2026)<\/code><\/pre>\n\n\n\n<\/span>\u8bf4\u660e<\/span><\/h2>\n\n\n\n\u5bf9\u6bcf\u4e2a\u7a97\u53e3(\u4e5f\u53ef\u4ee5\u4e0d\u6307\u5b9apartion,\u6240\u6709\u6570\u636e\u4e00\u4e2a\u7a97\u53e3\uff09\uff0c\u8fdb\u6307\u5b9a\u5217\u7684\u6392\u5e8f\uff08\u5982\u4e0d\u6392\u5e8f\uff0c\u5219\u9ed8\u8ba4\u987a\u5e8f)\uff0c\u7136\u540e\u8fd4\u56de\u3010\u622a\u6b62\u5230\u5f53\u524d\u884c\u7684\u3011\u7b2c\u4e00\u884c\u7684\u503c\u3002<\/p>\n\n\n\n
\u53c2\u6570\u53ef\u4ee5\u662f\u5b57\u6bb5\uff0c\u8868\u8fbe\u5f0f\u7b49\u3002<\/p>\n\n\n\n
\u6ce8\u610fnull\u503c\u5728\u6392\u5e8f\u4e2d\u7684\u5f71\u54cd\u3002\u5982\u679c\u4e0d\u786e\u5b9a\uff0c\u5efa\u8bae\u5bf9\u5b57\u6bb5\u505a\u63d0\u524d\u5904\u7406\uff0c\u6bd4\u5982nvl\u51fd\u6570\u3002<\/p>\n\n\n\n
<\/span>\u6837\u4f8b<\/span><\/h2>\n\n\n\n<\/span>\u6d4b\u8bd5\u6570\u636e<\/span><\/h3>\n\n\n\ngbase> create table td(id int, type int,val decimal(20,3));\r\nQuery OK, 0 rows affected (Elapsed: 00:00:00.17)\r\n\r\ngbase> insert into td values(1,1,111),(1,1,222),(2,1,333),(2,2,444),(3,2,555),(3,2,666),(4,2,777);\r\nQuery OK, 7 rows affected (Elapsed: 00:00:00.12)\r\nRecords: 7 Duplicates: 0 Warnings: 0\r\n\r\ngbase> insert into td values(5,1,null),(50,2,null);\r\nQuery OK, 2 rows affected (Elapsed: 00:00:00.09)\r\nRecords: 2 Duplicates: 0 Warnings: 0\r\n\r\ngbase> select * from td;\r\n+------+------+---------+\r\n| id | type | val |\r\n+------+------+---------+\r\n| 1 | 1 | 111.000 |\r\n| 1 | 1 | 222.000 |\r\n| 2 | 1 | 333.000 |\r\n| 2 | 2 | 444.000 |\r\n| 3 | 2 | 555.000 |\r\n| 3 | 2 | 666.000 |\r\n| 4 | 2 | 777.000 |\r\n| 5 | 1 | NULL |\r\n| 50 | 2 | NULL |\r\n+------+------+---------+\r\n9 rows in set (Elapsed: 00:00:00.03)<\/code><\/pre>\n\n\n\n<\/span>\u5b8c\u6574first_value\u7a97\u53e3\u7528\u6cd5<\/span><\/h3>\n\n\n\ngbase> select *,first_value(val)over(partition by type order by id) maxOfType from td;\r\n+------+------+---------+-----------+\r\n| id | type | val | maxOfType |\r\n+------+------+---------+-----------+\r\n| 1 | 1 | 111.000 | 111.000 |\r\n| 1 | 1 | 222.000 | 111.000 |\r\n| 2 | 1 | 333.000 | 111.000 |\r\n| 5 | 1 | NULL | 111.000 |\r\n| 2 | 2 | 444.000 | 444.000 |\r\n| 3 | 2 | 555.000 | 444.000 |\r\n| 3 | 2 | 666.000 | 444.000 |\r\n| 4 | 2 | 777.000 | 444.000 |\r\n| 50 | 2 | NULL | 444.000 |\r\n+------+------+---------+-----------+\r\n9 rows in set (Elapsed: 00:00:00.34)\r\n\r\ngbase> select *,first_value(val)over(partition by type order by id desc) maxOfType from td;\r\n+------+------+---------+-----------+\r\n| id | type | val | maxOfType |\r\n+------+------+---------+-----------+\r\n| 5 | 1 | NULL | NULL |\r\n| 2 | 1 | 333.000 | NULL |\r\n| 1 | 1 | 111.000 | NULL |\r\n| 1 | 1 | 222.000 | NULL |\r\n| 50 | 2 | NULL | NULL |\r\n| 4 | 2 | 777.000 | NULL |\r\n| 3 | 2 | 555.000 | NULL |\r\n| 3 | 2 | 666.000 | NULL |\r\n| 2 | 2 | 444.000 | NULL |\r\n+------+------+---------+-----------+\r\n9 rows in set (Elapsed: 00:00:00.14)\r\n\n<\/code><\/pre>\n\n\n\n<\/span>\u65e0partition \u7684first_value\u51fd\u6570\u7528\u6cd5<\/span><\/h3>\n\n\n\n\u6240\u6709\u6570\u636e\u6392\u5e8f\u540e\uff0c\u53d6\u7b2c\u4e00\u4e2a\u503c\u3002<\/p>\n\n\n\n
gbase> select *,first_value(val)over(order by id) maxOfType from td;\r\n+------+------+---------+-----------+\r\n| id | type | val | maxOfType |\r\n+------+------+---------+-----------+\r\n| 1 | 1 | 111.000 | 111.000 |\r\n| 1 | 1 | 222.000 | 111.000 |\r\n| 2 | 1 | 333.000 | 111.000 |\r\n| 2 | 2 | 444.000 | 111.000 |\r\n| 3 | 2 | 555.000 | 111.000 |\r\n| 3 | 2 | 666.000 | 111.000 |\r\n| 4 | 2 | 777.000 | 111.000 |\r\n| 5 | 1 | NULL | 111.000 |\r\n| 50 | 2 | NULL | 111.000 |\r\n+------+------+---------+-----------+\r\n9 rows in set (Elapsed: 00:00:00.10)\r\n\r\ngbase> select *,first_value(val)over(order by id desc) maxOfType from td;\r\n+------+------+---------+-----------+\r\n| id | type | val | maxOfType |\r\n+------+------+---------+-----------+\r\n| 50 | 2 | NULL | NULL |\r\n| 5 | 1 | NULL | NULL |\r\n| 4 | 2 | 777.000 | NULL |\r\n| 3 | 2 | 555.000 | NULL |\r\n| 3 | 2 | 666.000 | NULL |\r\n| 2 | 1 | 333.000 | NULL |\r\n| 2 | 2 | 444.000 | NULL |\r\n| 1 | 1 | 111.000 | NULL |\r\n| 1 | 1 | 222.000 | NULL |\r\n+------+------+---------+-----------+\r\n9 rows in set (Elapsed: 00:00:00.05)\r\n\n<\/code><\/pre>\n\n\n\n<\/span>\u6709partition\u65e0order\u7684first_value\u7528\u6cd5<\/span><\/h3>\n\n\n\n\u6bcf\u4e2a\u7a97\u53e3\u8fd4\u56de\u81ea\u7136\u987a\u5e8f\u7684\u7b2c\u4e00\u4e2a\u3002\u7531\u4e8e\u6570\u636e\u5e93\u5185\u5e76\u884c\uff0c\u65e0\u6cd5\u4fdd\u969c\u7ed3\u679c\u53ef\u91cd\u73b0\u3002<\/p>\n\n\n\n
gbase> select id,type,first_value(val)over(partition by type) maxOfType from td;\n+------+------+-----------+\ngbase> select *,first_value(val)over(partition by type) maxOfType from td;\r\n+------+------+---------+-----------+\r\n| id | type | val | maxOfType |\r\n+------+------+---------+-----------+\r\n| 1 | 1 | 222.000 | 222.000 |\r\n| 2 | 1 | 333.000 | 222.000 |\r\n| 5 | 1 | NULL | 222.000 |\r\n| 1 | 1 | 111.000 | 222.000 |\r\n| 3 | 2 | 666.000 | 666.000 |\r\n| 4 | 2 | 777.000 | 666.000 |\r\n| 3 | 2 | 555.000 | 666.000 |\r\n| 2 | 2 | 444.000 | 666.000 |\r\n| 50 | 2 | NULL | 666.000 |\r\n+------+------+---------+-----------+\r\n9 rows in set (Elapsed: 00:00:00.09)\r\n<\/code><\/pre>\n\n\n\n<\/span>\u6ca1\u6709partion\u548corder\u7684first_value\u7528\u6cd5<\/span><\/h3>\n\n\n\n\u6240\u6709\u6570\u636e\u4e00\u4e2a\u7a97\u53e3\uff0c\u9009\u81ea\u7136\u987a\u5e8f\u7684\u7b2c\u4e00\u4e2a\u3002 \u8fd9\u4e2a\u7528\u6cd5\u50cf\u6ca1\u5565\u610f\u4e49\u3002<\/p>\n\n\n\n
gbase> select *,first_value(val)over() maxOfType from td;\r\n+------+------+---------+-----------+\r\n| id | type | val | maxOfType |\r\n+------+------+---------+-----------+\r\n| 1 | 1 | 111.000 | 111.000 |\r\n| 1 | 1 | 222.000 | 111.000 |\r\n| 2 | 1 | 333.000 | 111.000 |\r\n| 2 | 2 | 444.000 | 111.000 |\r\n| 3 | 2 | 555.000 | 111.000 |\r\n| 3 | 2 | 666.000 | 111.000 |\r\n| 4 | 2 | 777.000 | 111.000 |\r\n| 5 | 1 | NULL | 111.000 |\r\n| 50 | 2 | NULL | 111.000 |\r\n+------+------+---------+-----------+\r\n9 rows in set (Elapsed: 00:00:00.08)\r\n\r\n\n<\/code><\/pre>","protected":false},"excerpt":{"rendered":"\u5357\u5927\u901a\u7528GBase 8a\u7684First_value\u51fd\u6570\uff0c\u8fd4\u56de\u6bcf\u7ec4\u7a97\u53e3\u91cc\u7684\u7b2c\u4e00\u4e2a\u503c\uff0c\u7c7b\u4f3crow_number\u662f\u7b49\u4e8e1\u7684\u3002\u672c\u6587\u4ecb\u7ecdfirst_value\u7684\u51fd\u6570\u7528\u6cd5\u5e76\u7ed9\u51fa\u4f7f\u7528\u4f8b\u5b50\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":[36,77],"class_list":["post-12473","post","type-post","status-publish","format-standard","hentry","category-gbase8a","tag-36","tag-olap"],"_links":{"self":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/12473","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=12473"}],"version-history":[{"count":5,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/12473\/revisions"}],"predecessor-version":[{"id":12488,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/12473\/revisions\/12488"}],"wp:attachment":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media?parent=12473"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/categories?post=12473"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/tags?post=12473"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}