更新时间:2023-02-26 12:47:18
在Oracle中,零长度的varchar被视为NULL.
Because in Oracle a ZERO length varchar is treated as NULL.
在您的示例中
NVL(NAME, ' ') AS NAME1 will evaluate to either NAME or ' ' - empty string.
NVL(NAME, '') as NAME2 will evaluate to either NAME or a zero length string