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ee.Join.saveFirst
使用集合让一切井井有条
根据您的偏好保存内容并对其进行分类。
返回一个联接，该联接将第一个集合中的每个元素与第二个集合中的匹配元素配对。第一个匹配项会作为附加属性添加到结果中。
| 用法 | 返回 |
|---|
ee.Join.saveFirst(matchKey, ordering, ascending, measureKey, outer) | 加入 |
| 参数 | 类型 | 详细信息 |
|---|
matchKey | 字符串 | 用于保存匹配结果的属性名称。 |
ordering | 字符串，默认值：null | 在选择第一个匹配项之前，用于对匹配项进行排序的属性。 |
ascending | 布尔值，默认值：true | 排序是否为升序。 |
measureKey | 字符串，默认值：null | 一个可选的属性名称，用于保存匹配时联接条件的衡量标准。 |
outer | 布尔值，默认值：false | 如果为 true，则结果中将包含没有匹配项的主行。 |
如未另行说明，那么本页面中的内容已根据知识共享署名 4.0 许可获得了许可，并且代码示例已根据 Apache 2.0 许可获得了许可。有关详情，请参阅 Google 开发者网站政策。Java 是 Oracle 和/或其关联公司的注册商标。
最后更新时间 (UTC)：2025-07-26。
[null,null,["最后更新时间 (UTC)：2025-07-26。"],[[["\u003cp\u003eThis function joins two collections by pairing elements based on matching property values.\u003c/p\u003e\n"],["\u003cp\u003eIt prioritizes the first match encountered and appends it as an additional property to the primary collection.\u003c/p\u003e\n"],["\u003cp\u003eUsers can specify sorting criteria for the matches using \u003ccode\u003eordering\u003c/code\u003e and \u003ccode\u003eascending\u003c/code\u003e parameters.\u003c/p\u003e\n"],["\u003cp\u003eOptionally, it allows saving the measure of the join condition and includes primary rows without matches if \u003ccode\u003eouter\u003c/code\u003e is true.\u003c/p\u003e\n"]]],["The `ee.Join.saveFirst` function creates a join between two collections, pairing each element from the first with its first matching element from the second. The matched element is stored as a new property, specified by `matchKey`. Matches can be sorted by `ordering` in `ascending` order before the first is selected. `measureKey` can be used to save the measurement of the join. Setting `outer` to true includes unmatched primary rows.\n"],null,["# ee.Join.saveFirst\n\nReturns a join that pairs each element from the first collection with a matching element from the second collection. The first match is added to the result as an additional property.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|------------------------------------------------------------------------------------------|---------|\n| `ee.Join.saveFirst(matchKey, `*ordering* `, `*ascending* `, `*measureKey* `, `*outer*`)` | Join |\n\n| Argument | Type | Details |\n|--------------|-------------------------|----------------------------------------------------------------------------------------|\n| `matchKey` | String | The property name used to save the match. |\n| `ordering` | String, default: null | The property on which to sort the matches before selecting the first. |\n| `ascending` | Boolean, default: true | Whether the ordering is ascending. |\n| `measureKey` | String, default: null | An optional property name used to save the measure of the join condition on the match. |\n| `outer` | Boolean, default: false | If true, primary rows without matches will be included in the result. |"]]
