如何在Select语句中声明SQL oracle中的空列
我试图在SELECT语句中创建空列,但它不起作用:如何在Select语句中声明SQL oracle中的空列,sql,oracle,null,Sql,Oracle,Null,我试图在SELECT语句中创建空列,但它不起作用: SELECT mytable. *, NULL as ColumnName FROM mytable; 错误代码为 Error report - SQL Error: ORA-01723: zero-length columns are not allowed 01723. 00000 - "zero-length columns are not allowed" *Cause: Columns with zero length we
SELECT mytable. *, NULL as ColumnName
FROM mytable;
错误代码为
Error report -
SQL Error: ORA-01723: zero-length columns are not allowed
01723. 00000 - "zero-length columns are not allowed"
*Cause: Columns with zero length were not allowed.
*Action: Correct the use of the column.
所以这似乎是不可能的。是否可以选择在SELECT语句中创建空列
谢谢,您可以cast()
NULL
转换为您想要的任何类型:
SELECT t.*, CAST(NULL as VARCHAR2(100)) as ColumnName
FROM mytable t;
注意:您的代码应该与SELECT
一样工作。如果您试图保存数据,则会出现问题