[jira] [Created] (CALCITE-1908) Mod function can't got exception in MOD(34.5,3), MOD(19,6.7) situation.

["sunjincheng (JIRA)" <ji...@apache.org>]

sunjincheng created CALCITE-1908:
------------------------------------

             Summary: Mod function can't got exception in MOD(34.5,3), MOD(19,6.7) situation.
                 Key: CALCITE-1908
                 URL: https://issues.apache.org/jira/browse/CALCITE-1908
             Project: Calcite
          Issue Type: Bug
            Reporter: sunjincheng


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:
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
https://issues.apache.org/jira/browse/CALCITE-1296
https://issues.apache.org/jira/browse/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. :)



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