fix #386

RELEASE-NOTES.md

 ## 2.0.0.M1
 
+### 功能提升
+
+1. [ISSUE #386](https://github.com/shardingjdbc/sharding-jdbc/issues/386) 支持SELECT 1这种不包含表名称的SQL
+
 ### 缺陷修正
 
 1. [ISSUE #387](https://github.com/shardingjdbc/sharding-jdbc/issues/387) 当函数+列名中存在'`'防止关键字时处理出错

sharding-jdbc-core/src/main/java/io/shardingjdbc/core/routing/router/ParsingSQLRouter.java

@@ -17,6 +17,7 @@
 
 package io.shardingjdbc.core.routing.router;
 
+import io.shardingjdbc.core.routing.type.all.DatabaseAllRoutingEngine;
 import io.shardingjdbc.core.rule.ShardingRule;
 import io.shardingjdbc.core.constant.DatabaseType;
 import io.shardingjdbc.core.jdbc.core.ShardingContext;
@@ -108,7 +109,9 @@ public final class ParsingSQLRouter implements SQLRouter {
     private RoutingResult route(final List<Object> parameters, final SQLStatement sqlStatement) {
         Collection<String> tableNames = sqlStatement.getTables().getTableNames();
         RoutingEngine routingEngine;
-        if (1 == tableNames.size() || shardingRule.isAllBindingTables(tableNames) || shardingRule.isAllInDefaultDataSource(tableNames)) {
+        if (tableNames.isEmpty()) {
+            routingEngine = new DatabaseAllRoutingEngine(shardingRule.getDataSourceMap());
+        } else if (1 == tableNames.size() || shardingRule.isAllBindingTables(tableNames) || shardingRule.isAllInDefaultDataSource(tableNames)) {
             routingEngine = new SimpleRoutingEngine(shardingRule, parameters, tableNames.iterator().next(), sqlStatement);
         } else {
             // TODO config for cartesian set

sharding-jdbc-core/src/main/java/io/shardingjdbc/core/routing/type/all/DatabaseAllRoutingEngine.java

+/*
+ * Copyright 1999-2015 dangdang.com.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * </p>
+ */
+
+package io.shardingjdbc.core.routing.type.all;
+
+import io.shardingjdbc.core.routing.type.RoutingEngine;
+import io.shardingjdbc.core.routing.type.RoutingResult;
+import io.shardingjdbc.core.routing.type.TableUnit;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+import javax.sql.DataSource;
+import java.util.Map;
+
+/**
+ * Database all routing engine.
+ * 
+ * @author zhangliang
+ */
+@RequiredArgsConstructor
+@Slf4j
+public final class DatabaseAllRoutingEngine implements RoutingEngine {
+    
+    private final Map<String, DataSource> dataSourceMap;
+    
+    @Override
+    public RoutingResult route() {
+        RoutingResult result = new RoutingResult();
+        for (String each : dataSourceMap.keySet()) {
+            result.getTableUnits().getTableUnits().add(new TableUnit(each, "", ""));
+        }
+        return result;
+    }
+}

sharding-jdbc-core/src/test/resources/integrate/assert/select.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <sqls>
+    <sql id="assertSelectOne">
+        <sharding-rule>
+            <data expected="select/SelectOne.xml" />
+        </sharding-rule>
+    </sql>
     <sql id="assertSelectNotEqualsWithSingleTable">
         <sharding-rule value="tbl">
             <data parameter="100000" expected="select/SelectNotEqualsWithSingleTable.xml" />

sharding-jdbc-core/src/test/resources/integrate/dataset/masterslave/expect/select/SelectOne.xml

+<dataset>
+    <t_order a="1" />
+</dataset>

sharding-jdbc-core/src/test/resources/integrate/dataset/sharding/db/expect/select/SelectOne.xml

+<dataset>
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+</dataset>

sharding-jdbc-core/src/test/resources/integrate/dataset/sharding/dbtbl/expect/select/SelectOne.xml

+<dataset>
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+</dataset>

sharding-jdbc-core/src/test/resources/integrate/dataset/sharding/masterslave/expect/select/SelectOne.xml

+<dataset>
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+    <t_order a="1" />
+</dataset>

sharding-jdbc-core/src/test/resources/integrate/dataset/sharding/tbl/expect/select/SelectOne.xml

+<dataset>
+    <t_order a="1" />
+</dataset>

sharding-jdbc-core/src/test/resources/parser/select.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <asserts>
+    <assert id="assertSelectOne">
+    </assert>
     <assert id="assertSelectNotEqualsWithSingleTable" parameters="1">
         <tables>
             <table name="t_order_item" />

sharding-jdbc-core/src/test/resources/sql/dql/select.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <sqls>
+    <sql id="assertSelectOne" value="SELECT 1 as a" />
     <sql id="assertSelectNotEqualsWithSingleTable" value="SELECT * FROM t_order_item WHERE item_id &lt;&gt; %s ORDER BY item_id" />
     <sql id="assertSelectNotEqualsWithSingleTableForExclamationEqual" value="SELECT * FROM t_order_item WHERE item_id != %s ORDER BY item_id" />
     <sql id="assertSelectNotEqualsWithSingleTableForNotIn" value="SELECT * FROM t_order_item WHERE item_id NOT IN (%s) ORDER BY item_id" />