PLS-00620

Error: PLS-00620: type mismatch found at 'string' among operands in a COALESCE expression

Causa: In a COALESCE expression, the operands do not match in datatype, and it is unclear which implicit conversion is required to correct the mismatch.

Acción: Change the operands so that their datatypes match. Consider using datatype conversion functions in the operands.