null command 中文意思是什麼
null command
解釋
空命令-
However, a line containing only spaces or tabs can appear ; this line is interpreted as a null command, and no error occurs
但是可以出現只包含空格或製表符的行;該行被解釋為空命令,並且不出現錯誤。 -
If you want to add a field called personid of type integer, which should not be null, and a field name of type character with a length of 42, which could be null, then the sql command would be
如果要添加名為personid和name的欄位,前者的欄位類型為integer ,並且不應該為null ,後者的欄位類型為character , length為42 ,並且可以為null ,那麼, sql命令將如下所示:
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