refine update statement parser

[tuohai666]

#168

[codecov-commenter]

Codecov Report

Merging #310 (f39da9d) into master (9482ba2) will not change coverage.
The diff coverage is 0.00%.

@@          Coverage Diff           @@
##           master    #310   +/-   ##
======================================
  Coverage    0.00%   0.00%           
======================================
  Files         382     382           
  Lines        6933    6929    -4     
  Branches     1218    1218           
======================================
+ Misses       6933    6929    -4     

Impacted Files	Coverage Δ
...phere/common/handler/UpdateStatementAssembler.java	0.00% <0.00%> (ø)

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