Mod function got exception in MOD(34.5,3), MOD(19,6.7) situation.

Calcite MOD definition:

		// Return type is same as divisor (2nd operand)
		// SQL2003 Part2 Section 6.27, Syntax Rules 9
		new SqlFunction(
			"MOD",
			SqlKind.OTHER_FUNCTION,
			ReturnTypes.ARG1_NULLABLE,
			null,
			OperandTypes.EXACT_NUMERIC_EXACT_NUMERIC,
			SqlFunctionCategory.NUMERIC);

Calcite Document description:

.bq MOD(numeric, numeric) Returns the remainder (modulus) of numeric1 divided by numeric2. The result is negative only if numeric1 is negative

 
MOD(34.5,3), mod(19,6.7)  异常:
 org.apache.calcite.sql.validate.SqlValidatorException: Cannot apply 'MOD' to arguments of type 'MOD(<DOUBLE>, <INTEGER>)'. Supported form(s): 'MOD(<EXACT_NUMERIC>, <EXACT_NUMERIC>)' at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

In MySQL: https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_mod
Modulo operation. Returns the remainder of N divided by M. We can get the correct value in MOD(34.5,3), MOD(19,6.7) situation.
MOD(34.5,3), mod(19,6.7) -> 1.5 , 5.6.

So, In this JIRA. we should do two thing:
1. Decide whether we are consistent with Mysql.
2. Improve the document, clearly inform the user for the MOD behavior.

Reference：

• https://docs.microsoft.com/en-us/sql/t-sql/data-types/data-type-conversion-database-engine
• CALCITE-1296
• CALCITE-613

Hi, julianhyde What do you think? Maybe this is related to implicit conversions. I am not sure. I appreciated if you can tell me your thoughts.