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https://issues.apache.org/jira/browse/CALCITE-1908?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16111462#comment-16111462
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Julian Hyde commented on CALCITE-1908:
--------------------------------------
Yes, we should support implicit conversion, if that is what is necessary.
The type of {{11.6}} should be {{DECIMAL(3, 1)}}. The type of {{2}} is
{{INTEGER}} (I think). Therefore the type of {{MOD(11.6, 2)}} is {{DECIMAL(3,
1)}}. The 2nd argument should be implicitly converted from {{INTEGER}} to
{{DECIMAL(3, 1)}}.
The implementation represents decimals as shifted integers. So, the implicit
conversion from {{INTEGER}} to {{DECIMAL(3, 1)}} will involve multiplying by 10.
I suggest that you first write a test in SqlValidatorTest to make sure that the
type derivation works. Then start worrying about the implementation (code
generation).
The underlying problem may well be that we have not officially implemented the
DECIMAL data type; see CALCITE-1468. Getting some of the disabled tests working
may be the most prudent approach.
> Mod function 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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