int(5) 转 varchar(5) check 异常报错

[MzCqueF56s6Z]

描述
表结构
CREATE TABLE test (
id int(5) DEFAULT NULL COMMENT 'test',
)
check sql:
ALTER TABLE test MODIFY COLUMN id varchar(4) default null COMMENT 'test' ;

runtime error: slice bounds out of range [:7] with capacity 6, goroutine 113 [running]:
github.com/hanchuanchuan/goInception/server.(*clientConn).Run.func1()
/data/goInception/server/conn.go:420 +0x7b
panic({0x17a0240?, 0xc0006c00f0?})
/app/go/src/runtime/panic.go:770 +0x132
github.com/hanchuanchuan/goInception/session.(*session).checkModifyColumn(0xc000672008, 0xc0006b5a00, 0xc0072a3dc0)
/data/goInception/session/session_inception.go:4115
/data/goInception/session/session_inception.go
有个字符串长度判断有问题
str := string([]byte(foundField.Type)[:7])
此处 foundField.Type 为6:
int(5)

因没深入理解代码逻辑，采用这样的方式临时处理:

`

            str := ""    

            if len(foundField.Type) < 7 {    

                str = foundField.Type        

            } else {    

                str = foundField.Type[:7]    

            }    

`