diff --git a/SQL_Schema_Repository.md b/SQL_Schema_Repository.md
index 37d0698..0232480 100644
--- a/SQL_Schema_Repository.md
+++ b/SQL_Schema_Repository.md
@@ -34,16 +34,13 @@ String sql = "CREATE TABLE `test1` (\n" +
         "  KEY `k_c` (`c_tinyint`,`c_int`),\n" +
         "  KEY `k_d` (`c_char`,`c_bigint`)\n" +
         ") ENGINE=InnoDB AUTO_INCREMENT=1769503 DEFAULT CHARSET=utf8mb4 COMMENT='10000000'";
-
-
 repository.console(sql);
 
+// 在如下的代码中可以知道repository中已经存在表test1
 MySqlCreateTableStatement createTableStmt = (MySqlCreateTableStatement) repository.findTable("test1").getStatement();
 assertEquals(21, createTableStmt.getTableElementList().size());
 
-//StringBuilder buf = new StringBuilder();
-//createTableStmt.showCoumns(buf);
-
+// 通过执行命令"show columns from test1"可以获得mysql console风格的输出
 assertEquals("+--------------+---------------+------+-----+---------------------+-----------------------------+\n" +
         "| Field        | Type          | Null | Key | Default             | Extra                       |\n" +
         "+--------------+---------------+------+-----+---------------------+-----------------------------+\n" +
@@ -66,6 +63,7 @@ assertEquals("+--------------+---------------+------+-----+---------------------
         "| c_longblob   | longblob      | YES  |     | NULL                |                             |\n" +
         "+--------------+---------------+------+-----+---------------------+-----------------------------+\n", repository.console("show columns from test1"));
 
+// 执行alter语句，修改repository中内容
 repository.console("alter table test1 drop column c_decimal;");
 assertEquals(20, createTableStmt.getTableElementList().size());