Updated SQL_Schema_Repository (markdown)

SQL_Schema_Repository.md

@@ -91,4 +91,52 @@ assertEquals("+--------------+--------------+------+-----+---------------------+
         "+--------------+--------------+------+-----+---------------------+-----------------------------+\n", 
 repository.console("show columns from test1"));
 
+```
+
+3. Column Resolve
+```java
+final String dbType = JdbcConstants.MYSQL;
+
+SchemaRepository repository = new SchemaRepository(dbType);
+
+repository.console("create table t_emp(emp_id bigint, name varchar(20));");
+repository.console("create table t_org(org_id bigint, name varchar(20));");
+
+String sql = "SELECT emp_id, a.name AS emp_name, org_id, b.name AS org_name\n" +
+        "FROM t_emp a\n" +
+        "\tINNER JOIN t_org b ON a.emp_id = b.org_id";
+
+List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, dbType);
+assertEquals(1, stmtList.size());
+
+SQLSelectStatement stmt = (SQLSelectStatement) stmtList.get(0);
+SQLSelectQueryBlock queryBlock = stmt.getSelect().getQueryBlock();
+
+// 大小写不敏感
+assertNotNull(queryBlock.findTableSource("A"));
+assertSame(queryBlock.findTableSource("a"), queryBlock.findTableSource("A"));
+
+assertNull(queryBlock.findTableSourceWithColumn("emp_id"));
+
+// 使用repository做column resolve
+repository.resolve(stmt);
+
+assertNotNull(queryBlock.findTableSourceWithColumn("emp_id"));
+
+SQLExprTableSource tableSource = (SQLExprTableSource) queryBlock.findTableSourceWithColumn("emp_id");
+assertNotNull(tableSource.getSchemaObject());
+
+SQLCreateTableStatement createTableStmt = (SQLCreateTableStatement) tableSource.getSchemaObject().getStatement();
+assertNotNull(createTableStmt);
+
+SQLSelectItem selectItem = queryBlock.findSelectItem("org_name");
+assertNotNull(selectItem);
+SQLPropertyExpr selectItemExpr = (SQLPropertyExpr) selectItem.getExpr();
+SQLColumnDefinition column = selectItemExpr.getResolvedColumn();
+assertNotNull(column);
+assertEquals("name", column.getName().toString());
+assertEquals("t_org", (((SQLCreateTableStatement)column.getParent()).getName().toString()));
+
+assertSame(queryBlock.findTableSource("B"), selectItemExpr.getResolvedTableSource());
+
 ```