bugfix: error image when use null value as image query condition in insert on duplicate

[renliangyu857]

…ecutor

• I have registered the PR changes.

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

fixes #4956

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[lgtm-com]

This pull request introduces 1 alert when merging 6128575 into e10e36c - view on LGTM.com

new alerts:

• 1 for Dereferenced variable may be null

[funky-eyes]

LGTM @slievrly @jsbxyyx PTAL

[codecov-commenter]

Codecov Report

Merging #5031 (78ade4e) into develop (f0e25a6) will decrease coverage by 0.01%.
The diff coverage is 41.66%.

@@              Coverage Diff              @@
##             develop    #5031      +/-   ##
=============================================
- Coverage      49.42%   49.40%   -0.02%     
+ Complexity      4125     4124       -1     
=============================================
  Files            734      734              
  Lines          26054    26058       +4     
  Branches        3220     3221       +1     
=============================================
- Hits           12877    12874       -3     
- Misses         11803    11805       +2     
- Partials        1374     1379       +5     

Impacted Files	Coverage Δ
...ec/mysql/MySQLInsertOnDuplicateUpdateExecutor.java	32.47% <41.66%> (+1.94%)	⬆️
...n/src/main/java/io/seata/common/util/IdWorker.java	77.08% <0.00%> (-6.25%)	⬇️
...in/java/io/seata/server/session/GlobalSession.java	78.68% <0.00%> (-0.78%)	⬇️
...torage/file/store/FileTransactionStoreManager.java	55.62% <0.00%> (-0.65%)	⬇️
...erver/storage/file/session/FileSessionManager.java	49.04% <0.00%> (-0.64%)	⬇️

[funky-eyes]

需要顺便把上述去重后多余的or去掉
其次https://github.com/seata/seata/pull/5028/files 依赖此pr,否者当存在uk且没有默认值是,会出现is "null"的条件导致sql报错
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''NULL' ) OR (test_id2 is 'NULL' ) FOR UPDATE' at line 1

[renliangyu857]

1、问题
insert on duplicate update语句中DB对于null值唯一索引或主键不会进行匹配，所以索引值为空或null时，不应该作为查询前置镜像的条件。
2、测试
建表语句：
CREATE TABLE t_unique (
id int(11) NOT NULL,
a int(11) DEFAULT NULL,
b int(11) DEFAULT NULL,
PRIMARY KEY (id),
UNIQUE KEY a (a)
) ENGINE=InnoDB DEFAULT CHARSET=utf8；
insert into t_unique(id,b) values(1,1)
测试Case：

1. insert into t_unique(id,b) values(1,2) on duplicate key update b = 5
   这种情况正确的查询条件应该是只有where id = 1
   2）insert into t_unique(id,a,b) values(1,null,2) on duplicate key update b = 5
   这种情况识别到值为NULL对象，正确的查询条件应该是只有where id = 1

[funky-eyes]

问题记录: insert on duplicate 中存在从tablematedata读取唯一索引的时候没有判断是否需要加上转义符,假设这个所以是一个关键字,此时前镜像查询的sql会报错

[caohdgege]

LGTM