[BUG] WallUtils针对union、验证疑似异常，包含MINUS、EXCEPT、INTERSECT

[dev-GGBond]

Database Type

MySQL

Database Version

none

Druid Version

1.2.23以及旧版本1.2.16，其他版本未测试

JDK Version

jdk1.8

Error SQL

select * from t union select * from t2

Testcase Code

public class WallUnionTest extends TestCase {
private static final String UNION_SQL1 = "select f1, f2 from t where f1=1 union select 1, 2";
private static final String UNION_SQL2 = "select f1, f2 from t where f1=1 union select f1,f2 from t2 where id >10";
private static final String UNION_SQL3 = "select * from t union select * from t2";

public void testMySql() throws Exception {
    WallConfig config = new WallConfig();
    config.setSelectUnionCheck(true);
    System.out.println(WallUtils.isValidateMySql(UNION_SQL1, config));
    System.out.println(WallUtils.isValidateMySql(UNION_SQL2, config));
    System.out.println(WallUtils.isValidateMySql(UNION_SQL3, config));
}

}

Stacktrace Info

false
true
true

Error Info

union右侧带from则会检测异常，如：union select 1, 2则正常，select f1,f2 from t2 where id >10则异常，异常还包含其他拦截MINUS、EXCEPT、INTERSECT