什么是 SQL“伪列"?

问题描述

我不小心编码了 SELECT $FOO.. 并得到错误无效伪列$FOO".

I accidentally coded SELECT $FOO.. and got the error "Invalid pseudocolumn "$FOO".

我找不到他们的任何文档.这是我应该知道的吗?

I can't find any documentation for them. Is it something I should know?

这是一个 MS SQL Server 特定问题.

this is a MS SQL Server specific question.

推荐答案

伪列是实际列的符号别名，具有特殊属性，例如，$IDENTITY 是分配了 IDENTITY 的列的别名，$ROWGUID 表示分配了 ROWGUIDCOL 的列.它用于内部管道脚本.

Pseudocolumns are symbolic aliases for actual columns, that have special properties, for example, $IDENTITY is an alias for the column that has the IDENTITY assigned, $ROWGUID for the column with ROWGUIDCOL assigned. It's used for the internal plumbing scripts.

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