Do not support sum(if()) expression

[joooohnli]

Bug Report

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Which version of ShardingSphere did you use?

3.1.0

Which project did you use? Sharding-JDBC or Sharding-Proxy?

Sharding-JDBC

Expected behavior

support

Actual behavior

do not

Reason analyze (If you can)

sql parsing error

Steps to reproduce the behavior, such as: SQL to execute, sharding rule configuration, when exception occur etc.

1. select sum(if(status=0, 1, 0)) from xx group by xx;
2. Table 'xx.xx' doesn't exist

Example codes for reproduce this issue (such as a github link).

[codefairy08]

IF is a keyword, When the function nested function . the inner functionname is the keyword， it failed parsing