The column order is the same for all rows in a given table. Columns are usually stored
in the order in which they were listed in the CREATE TABLE statement, but this is not
guaranteed. For example, if a table has a column of datatype LONG, then Oracle always
stores this column last. Also, if a table is altered so that a new column is added, then
the new column becomes the last column stored.
In general, try to place columns that frequently contain nulls last so that rows take less
space. Note, though, that if the table you are creating includes a LONG column as well,
then the benefits of placing frequently null columns last are lost.
列顺序
1. 一个表含有数据类型 为 LONG 的列,那么 Oracle 会将此列排在最后 .
2. 一般来说,应该将出现空值较多的列放在最后 .
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