<\/span><\/h2>\n\n\n\nLEAD\/LAG(expr [,offset [,DEFAULT]] ) OVER([PARTITION BY col_name1,col_name2,\u2026] ORDER BY col_name1 [ASC\/DESC], col_name2 [ASC\/DESC],\u2026)\r<\/code><\/pre>\n\n\n\n<\/span>\u8bf4\u660e<\/span><\/h2>\n\n\n\nLEAD \u8d85\u524d\uff0c\u4e5f\u5c31\u662f\u540e\u9762\u7684\u65b0\u6570\u636e\uff0cLAG \u6ede\u540e\uff0c\u4e5f\u5c31\u662f\u4ee5\u524d\u7684\u65e7\u6570\u636e\u3002<\/p>\n\n\n\n
- expr\uff1a\u6b64\u53c2\u6570\u662f\u6c42\u504f\u79fb\u91cf\u7684\u8868\u8fbe\u5f0f\u3002<\/li>
- offset\uff1a\u6b64\u53c2\u6570\u662f\u504f\u79fb\u91cf\uff0c\u53ef\u4ee5\u7701\u7565\uff0c\u9ed8\u8ba4\u503c\u662f 1\u3002<\/li>
- default\uff1a\u6b64\u53c2\u6570\u662f\u7f3a\u7701\u503c\uff0c\u53ef\u4ee5\u7701\u7565\uff0c\u9ed8\u8ba4\u503c\u662f NULL\u3002<\/li>
- \u8fd9\u4e24\u4e2a\u51fd\u6570 OVER \u91cc\u9762\u7684\u89c4\u5219\u540c RANK \u7c7b OLAP \u51fd\u6570\u4e00\u6837\u3002<\/li>
- \u8be5\u51fd\u6570\u53ef\u4ee5\u8fd4\u56de\u4efb\u4f55\u652f\u6301\u7684\u6570\u636e\u7c7b\u578b\u3002<\/li><\/ol>\n\n\n\n
\u53c2\u65702\u548c\u53c2\u65703\u5fc5\u987b\u662f\u5e38\u91cf\u6216\u5e38\u91cf\u8868\u8fbe\u5f0f\u3002\u7b2c\u4e00\u4e2a\u53c2\u6570\u4e0e\u7b2c\u4e09\u4e2a\u53c2\u6570\u7684\u6570\u636e\u7c7b\u578b\u4e0d\u540c\u65f6\uff0c\u7b2c\u4e09\u4e2a\u53c2\u6570\u4f1a\u6839\u636e\u7b2c\u4e00\u4e2a\u53c2\u6570\u7684\u6570\u636e\u7c7b\u578b\u505a\u9690\u5f0f\u8f6c\u6362\u3002<\/p>\n\n\n\n
<\/span>\u6837\u4f8b<\/span><\/h2>\n\n\n\n<\/span>lead\u6837\u4f8b<\/span><\/h3>\n\n\n\n\u83b7\u53d6\u7684\u662f\u540e\u9762\u65b0\u7684\u6570\u636e\uff0c\u9ed8\u8ba4\u662f\u540e1\u884c\u3002\u901a\u8fc7\u7b2c2\u4e2a\u53c2\u6570\uff0c\u6307\u5b9a\u540e\u9762\u7b2c\u51e0\u884c\uff0c\u4f8b\u5b50\u4e2d\u662f\u540e\u9762\u7b2c2\u884c\u3002 \u5982\u679c\u540e\u9762\u6ca1\u6709\u4e86\uff0c\u9ed8\u8ba4\u8fd4\u56denull, \u901a\u8fc7\u7b2c3\u4e2a\u53c2\u6570\uff0c\u66ff\u6362\u8fd9\u4e2anull\u503c\u3002<\/p>\n\n\n\n| select t2.*,lead(val) over(order by val) v from t2;<\/td> | select t2.*,lead(val,2<\/span>) over(order by val) v from t2;<\/td> | select t2.*,lead(val,2,-1<\/span>) over(order by val) v from t2;<\/td><\/tr>+------+------+------+------+
| id | type | val | v |
+------+------+------+------+
| 1 | 1 | 111 | 122 |
| 2 | 1 | 122 | 133 |
| 3 | 1 | 133 | 222 |
| 4 | 2 | 222 | 233 |
| 5 | 2 | 233 | 244 |
| 6 | 2 | 244 | 333 |
| 7 | 3 | 333 | NULL |
+------+------+------+------+
7 rows in set (Elapsed: 00:00:00.05)<\/code><\/td>+------+------+------+------+
| id | type | val | v |
+------+------+------+------+
| 1 | 1 | 111 | 133 |
| 2 | 1 | 122 | 222 |
| 3 | 1 | 133 | 233 |
| 4 | 2 | 222 | 244 |
| 5 | 2 | 233 | 333 |
| 6 | 2 | 244 | NULL |
| 7 | 3 | 333 | NULL |
+------+------+------+------+
7 rows in set (Elapsed: 00:00:00.02)<\/code><\/td>+------+------+------+------+
| id | type | val | v |
+------+------+------+------+
| 1 | 1 | 111 | 133 |
| 2 | 1 | 122 | 222 |
| 3 | 1 | 133 | 233 |
| 4 | 2 | 222 | 244 |
| 5 | 2 | 233 | 333 |
| 6 | 2 | 244 | -1 |
| 7 | 3 | 333 | -1 |
+------+------+------+------+
7 rows in set (Elapsed: 00:00:00.02)<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<\/span>LAG\u6837\u4f8b<\/span><\/h3>\n\n\n\n\u548cLEAD\u7c7b\u4f3c\uff0c\u53ea\u662f\u627e\u7684\u662f\u524d\u9762\u51fa\u73b0\u8fc7\u7684\u65e7\u6570\u636e\u3002\u53c2\u6570\u4e5f\u4e00\u6837\u3002<\/p>\n\n\n\n| select t2.*,lag(val) over(order by val) v from t2;<\/td> | select t2.*,lag(val,2) over(order by val) v from t2;<\/td> | select t2.*,lag(val,2,-1) over(order by val) v from t2;<\/td><\/tr> | +------+------+------+------+
| id | type | val | v |
+------+------+------+------+
| 1 | 1 | 111 | NULL |
| 2 | 1 | 122 | 111 |
| 3 | 1 | 133 | 122 |
| 4 | 2 | 222 | 133 |
| 5 | 2 | 233 | 222 |
| 6 | 2 | 244 | 233 |
| 7 | 3 | 333 | 244 |
+------+------+------+------+
7 rows in set (Elapsed: 00:00:00.02)<\/code><\/td>+------+------+------+------+
| id | type | val | v |
+------+------+------+------+
| 1 | 1 | 111 | NULL |
| 2 | 1 | 122 | NULL |
| 3 | 1 | 133 | 111 |
| 4 | 2 | 222 | 122 |
| 5 | 2 | 233 | 133 |
| 6 | 2 | 244 | 222 |
| 7 | 3 | 333 | 233 |
+------+------+------+------+
7 rows in set (Elapsed: 00:00:00.02)<\/code><\/td>+------+------+------+------+
| id | type | val | v |
+------+------+------+------+
| 1 | 1 | 111 | -1 |
| 2 | 1 | 122 | -1 |
| 3 | 1 | 133 | 111 |
| 4 | 2 | 222 | 122 |
| 5 | 2 | 233 | 133 |
| 6 | 2 | 244 | 222 |
| 7 | 3 | 333 | 233 |
+------+------+------+------+
7 rows in set (Elapsed: 00:00:00.02)<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<\/span>\u5e26PARTITION\u7684LEAD\u548cLAG\u6837\u4f8b<\/span><\/h3>\n\n\n\n\u6bcf\u4e2apartition\u5404\u81ea\u8ba1\u7b97\u3002<\/p>\n\n\n\n gbase> select t2.*,lead(val) over(partition by type order by val) v from t2;\r\n+------+------+------+------+\r\n| id | type | val | v |\r\n+------+------+------+------+\r\n| 4 | 2 | 222 | 233 |\r\n| 5 | 2 | 233 | 244 |\r\n| 6 | 2 | 244 | NULL |\r\n| 1 | 1 | 111 | 122 |\r\n| 2 | 1 | 122 | 133 |\r\n| 3 | 1 | 133 | NULL |\r\n| 7 | 3 | 333 | NULL |\r\n+------+------+------+------+\r\n7 rows in set (Elapsed: 00:00:00.06)\r\n\r\ngbase> select t2.*,lag(val) over(partition by type order by val) v from t2;\r\n+------+------+------+------+\r\n| id | type | val | v |\r\n+------+------+------+------+\r\n| 4 | 2 | 222 | NULL |\r\n| 5 | 2 | 233 | 222 |\r\n| 6 | 2 | 244 | 233 |\r\n| 1 | 1 | 111 | NULL |\r\n| 2 | 1 | 122 | 111 |\r\n| 3 | 1 | 133 | 122 |\r\n| 7 | 3 | 333 | NULL |\r\n+------+------+------+------+\r\n7 rows in set (Elapsed: 00:00:00.05)\r\n<\/code><\/pre>","protected":false},"excerpt":{"rendered":"\u672c\u6587\u4ecb\u7ecdGBase 8a\u7684\u7a97\u53e3\u51fd\u6570LEAD\u3001LAG\u7684\u4f7f\u7528\u65b9\u6cd5\u548c\u6837\u4f8b\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-6635","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\/6635","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=6635"}],"version-history":[{"count":17,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/6635\/revisions"}],"predecessor-version":[{"id":6749,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/6635\/revisions\/6749"}],"wp:attachment":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media?parent=6635"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/categories?post=6635"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/tags?post=6635"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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