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From "sunjincheng (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (FLINK-6891) Add LOG supported in SQL
Date Thu, 15 Jun 2017 08:05:00 GMT

     [ https://issues.apache.org/jira/browse/FLINK-6891?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

sunjincheng updated FLINK-6891:
-------------------------------
    Description: 
LOG(X), LOG(B,X)

If called with one parameter, this function returns the natural logarithm of X. If X is less
than or equal to 0.0E0, the function returns NULL and (as of MySQL 5.7.4) a warning “Invalid
argument for logarithm” is reported.
The inverse of this function (when called with a single argument) is the EXP() function.

If called with two parameters, this function returns the logarithm of X to the base B. If
X is less than or equal to 0, or if B is less than or equal to 1, then NULL is returned.
* Example:
 LOG(2) -> 0.69314718055995
 LOG(-2) -> NULL
 LOG(2,65536) -> 16
 LOG(10,100) -> 2
 LOG(1,100) -> NULL

* See more:
** [MySQL| https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_log]



  was:
LONG (N) A single parameter version of the function returns the natural logarithm of N, and
if two arguments are called, it returns any radix of the logarithm of N. 
* Syntax:
LOG ( float_expression [, base ] )  

* Arguments
**float_expression:  Is an expression of type float or of a type that can be implicitly converted
to float.
**base: Optional integer argument that sets the base for the logarithm.

* Return Types
  float

* Example:
  LOG(10) -> 2.30

* See more:
** [MSQL|https://docs.microsoft.com/en-us/sql/t-sql/functions/log-transact-sql]
** [MySQL| https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_log]




> Add LOG supported in SQL
> ------------------------
>
>                 Key: FLINK-6891
>                 URL: https://issues.apache.org/jira/browse/FLINK-6891
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>    Affects Versions: 1.4.0
>            Reporter: sunjincheng
>            Assignee: sunjincheng
>
> LOG(X), LOG(B,X)
> If called with one parameter, this function returns the natural logarithm of X. If X
is less than or equal to 0.0E0, the function returns NULL and (as of MySQL 5.7.4) a warning
“Invalid argument for logarithm” is reported.
> The inverse of this function (when called with a single argument) is the EXP() function.
> If called with two parameters, this function returns the logarithm of X to the base B.
If X is less than or equal to 0, or if B is less than or equal to 1, then NULL is returned.
> * Example:
>  LOG(2) -> 0.69314718055995
>  LOG(-2) -> NULL
>  LOG(2,65536) -> 16
>  LOG(10,100) -> 2
>  LOG(1,100) -> NULL
> * See more:
> ** [MySQL| https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_log]



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