[function]The result of abs('') is wrong

[lvchenyang-maker]

Steps to reproduce the behavior (Required)

select abs('');

abs函数不支持date 、datetime但是计算时会有隐式转换, date: abs(CAST(1: k1 AS LARGEINT)) datatime:abs(CAST(2: k2 AS DOUBLE))建议优化

Expected behavior (Required)

mysql 5.7 0

Real behavior (Required)

null

StarRocks version (Required)

• You can get the StarRocks version by executing SQL select current_version()

+----------------------+
| current_version()    |
+----------------------+
| MAIN-RELEASE 9cada5e |
+----------------------+