improve set datatype for mysql 5.7

src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java

@@ -1327,6 +1327,7 @@ public class SQLExprParser extends SQLParser {
                 case SCHEMA:
                 case INTERVAL:
                 case EXPLAIN:
+                case SET:
                     identName = lexer.stringVal();
                     lexer.nextToken();
                     break;

src/test/java/com/alibaba/druid/bvt/sql/mysql/createTable/MySqlCreateTableTest92.java

@@ -0,0 +1,29 @@
+package com.alibaba.druid.bvt.sql.mysql.createTable;
+
+import com.alibaba.druid.sql.MysqlTest;
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlCreateTableStatement;
+import com.alibaba.druid.sql.dialect.mysql.parser.MySqlStatementParser;
+import org.junit.Assert;
+
+import java.util.List;
+
+public class MySqlCreateTableTest92 extends MysqlTest {
+
+    public void test_0() throws Exception {
+        String sql = "CREATE TABLE `test` (\n"
+                     + "  `id`  bigint(20) unsigned zerofill NOT NULL AUTO_INCREMENT COMMENT 'id',\n"
+                     + "  `c_set` set('a','b','c') COMMENT 'set',\n" + "  PRIMARY KEY (`id`)\n"
+                     + ") ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4 COMMENT='10000000';";
+
+        MySqlStatementParser parser = new MySqlStatementParser(sql);
+        List<SQLStatement> statementList = parser.parseStatementList();
+        MySqlCreateTableStatement statemen = (MySqlCreateTableStatement)statementList.get(0);
+
+        Assert.assertEquals(1, statementList.size());
+        Assert.assertEquals(3, statemen.getTableElementList().size());
+        Assert.assertEquals("`c_set` set('a', 'b', 'c') COMMENT 'set'", SQLUtils.toMySqlString(statemen.getTableElementList().get(1)));
+
+    }
+}