4.2.1. Column References

4.2.1. Column References

4.2.1. 列引用

A column can be referenced in the form:

可这样引用一个列：

correlation.columnname

correlation is the name of a table (possibly qualified with a schema name), or an alias for a table defined by means of a FROM clause. The correlation name and separating dot can be omitted if the column name is unique across all the tables being used in the current query. (See also Chapter 7.)

correlation是一个表名（也可使用模式名限定），也可以是from子句后面对表指定的别名。如果在当前查询中，列名是唯一的，那么可以省略表名及其后的点号。（另请参见第七章）