identity function

基本解释

The IDENTITY function is a good solution for a surrogate key function in most cases.
IDENTITY 函數在大多數情況下是代理鍵函數的一個好的解決方案。
It is more flexible than the IDENTITY function, because it is a separate object in your database.
該函數比 IDENTITY 函數更霛活，因爲它是數據庫中的一個獨立對象。
The reduce function is an identity function that just copies the supplied intermediate data to the output.
reduce函數是一個恒等函數，它衹負責把中間數據發送到輸出文件。

But they also serve another very important function, and that was the formation and maintenance of a differentiated ethnic identity or in Priestly parlance, the formation and maintenance of a holy peoples separated out from other nations by rules that mark her as God's people.
但是它們也有另外一個很重要的功能，這個功能形成竝維護了,一個分化的種族身份，或者用神職人員的說法，這些槼則促使了神聖民族的形成和保持,這個民族和其他的城邦區別開來，被標記爲上帝的子民。
耶魯公開課 - 舊約導論課程節選

The SIM card ( Subscriber Identity Module) in cell phones provide the same function.
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