修复审核MySQL8.0更改列类型时报数组越界的错误问题

[davidzhangbj]

goInception版本：goInception-linux-v1.3.0-94-g2f06c61b95.tar.gz
mysql版本：8.0.20
mysql表结构：create table t1 (id bigint unsigned not null primary key auto_increment, c1 int not null default '0');
alter语句：alter table t1 change column c1 c1 varchar(256) not null default '';
使用goInception审核这个alter语句时报：“slice bounds out of range [:7) with capacity 3”错误，原因是同一个建表语句，mysql5.7为int(11),mysql8.0为int
mysql8.0.20

mysql5.7.44

所以在截取时对foundField.Type做判断，如果foundField.Type长度小于7位，以实际长度进行截取，如果大于等于7位，就按照7位进行截取

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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