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If omitted, \u003cem\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e defaults to 1 and \u003cem\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e to \u003ccode\u003eNULL\u003c/code\u003e.","SourceRevision":"wiki-repair-20261023:3a624abf9d79693182d04de9fcd562246e1b356baed798c441c9a2eb7d81dd0a","ContentHash":"fb94f6d48538e1861a6c930c7d006a5f212370471cf8b048b0a7f31615784232","Payload":{"description":"Returns value evaluated at the row that is offset rows before the current row within the partition; if there is no such row, instead returns default (which must be of a type compatible with value). Both offset and default are evaluated with respect to the current row. 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If omitted, \u003cem class=\"parameter\"\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e defaults to 1 and \u003cem class=\"parameter\"\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e to \u003ccode class=\"literal\"\u003eNULL\u003c/code\u003e.","signatures":[{"description":"Returns value evaluated at the row that is offset rows before the current row within the partition; if there is no such row, instead returns default (which must be of a type compatible with value). Both offset and default are evaluated with respect to the current row. 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If omitted, \u003cem class=\"parameter\"\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e defaults to 1 and \u003cem class=\"parameter\"\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e to \u003ccode class=\"literal\"\u003eNULL\u003c/code\u003e.","description_zh":"返回在分区内当前行之前 offset 行处计算的 value；如果没有这样的行，则返回 default（其类型必须与 value 兼容）。offset 和 default 都针对当前行求值。如果省略，offset 默认为 1，default 默认为 NULL。","description_zh_html":"返回在分区内当前行之前 \u003cem class=\"parameter\"\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e 行处计算的 \u003cem class=\"parameter\"\u003e\u003ccode\u003evalue\u003c/code\u003e\u003c/em\u003e；如果没有这样的行，则返回 \u003cem class=\"parameter\"\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e（其类型必须与 \u003cem class=\"parameter\"\u003e\u003ccode\u003evalue\u003c/code\u003e\u003c/em\u003e 兼容）。\u003cem class=\"parameter\"\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e 和 \u003cem class=\"parameter\"\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e 都针对当前行求值。如果省略，\u003cem class=\"parameter\"\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e 默认为 1，\u003cem class=\"parameter\"\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e 默认为 \u003ccode class=\"literal\"\u003eNULL\u003c/code\u003e。","examples":[],"html":"\u003ccode class=\"function\"\u003elag\u003c/code\u003e ( \u003cem class=\"parameter\"\u003e\u003ccode\u003evalue\u003c/code\u003e\u003c/em\u003e \u003ccode class=\"type\"\u003eanycompatible\u003c/code\u003e [\u003cspan class=\"optional\"\u003e, \u003cem class=\"parameter\"\u003e\u003ccode\u003eoffset\u003c/code\u003e\u003c/em\u003e \u003ccode class=\"type\"\u003einteger\u003c/code\u003e [\u003cspan class=\"optional\"\u003e, \u003cem class=\"parameter\"\u003e\u003ccode\u003edefault\u003c/code\u003e\u003c/em\u003e \u003ccode class=\"type\"\u003eanycompatible\u003c/code\u003e\u003c/span\u003e ]\u003c/span\u003e] ) → \u003ccode class=\"returnvalue\"\u003eanycompatible\u003c/code\u003e","returns":"anycompatible","text":"lag ( value anycompatible [, offset integer [, default anycompatible ]] ) → anycompatible","zh_from":"same-version-pgdoc"}]}},"RequestedLocale":"en","Fallback":false,"Versions":["10","11","12","13","14","15","16","17","18","19","20","8.4","9.0","9.1","9.2","9.3","9.4","9.5","9.6"],"Locales":["en","zh-Hans"],"Signatures":[{"Version":"18","Ordinal":0,"Hash":"df66cb7ed402ae5ddd0dfcf9f694d4ba487e5c0f30aab17b2a0a3834de5c0a62","Text":"lag ( value anycompatible [, offset integer [, default anycompatible ]] ) → anycompatible","Returns":"anycompatible","Payload":{"description":"Returns value evaluated at the row that is offset rows before the current row within the partition; if there is no such row, instead returns default (which must be of a type compatible with value). 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