使用SELECT语句的输出返回SQL函数中的char值

I want to create a Function that outputs a CHAR value. I managed to create a SELECT statement that outputs only the column and row of that one particular value I need. However, when I try to use this function I get an error code stating that the output value is not valid (SQLCODE=-946-Result set not permitted) My function looks like this:I want to create a Function that outputs a CHAR