Mybatis中SqlNode的组合模式 顶

<select id="findByGameTypeCount" resultType="java.lang.Long">
   select count(*)
   from betdetails a inner join UserBetOrder b on a.orderId = b.id
   <where>
      <if test="gameType != null and gameType > 0">
         a.gameType = #{gameType} and
      </if>
      <if test="currDrawno != null">
         b.currentDrawno = #{currDrawno} and
      </if>
      <if test="orderId != null and orderId > 0">
         a.orderId = #{orderId} and
      </if>
      <if test="status != null and status >= 0">
         a.status = #{status} and
      </if>
      <if test="userId != null and userId > 0">
         b.userId = #{userId} and
      </if>
      <if test="start != null">
         a.createTime &gt;= #{start} and
      </if>
      <if test="end != null">
         a.createTime &lt;= #{end} and
      </if>
      1 = 1
   </where>
</select>

<insert id="insertBetdetailsByBatch" parameterType="java.util.List">
   insert into betdetails(id,orderId,actorIndex,createTime,ballIndex,ballValue,betAmount,rate1,rate2,rate3,gameType,status,betResult,awardAmount,ballName) values
   <foreach collection="list" item="item" index="index" separator=",">
      (#{item.id},#{item.orderId},#{item.actorIndex},#{item.createTime},#{item.ballIndex},#{item.ballValue},#{item.betAmount},#{item.rate1},#{item.rate2},#{item.rate3},#{item.gameType},#{item.status},#{item.betResult},#{item.awardAmount},#{item.ballName})
   </foreach>
</insert>

public interface SqlNode {
  //SqlNode接口中定义的唯一方法，该方法会根据用户传入的实参，解析该SqlNode所记录的动态SQL节点，并调用DynamicContext.appendSql()方法将解析后的SQL片段追加到
  //DynamicContext.sqlBuilder中保存
  //当SQL节点下的所有SqlNode完成解析后，就可以从DynamicContext中获取一条动态生成的完整的SQL语句
  boolean apply(DynamicContext context);
}

private final ContextMap bindings; //参考上下文
//在SqlNode解析动态SQL时，会将解析后的SQL语句片段添加到该属性中保存，最终拼凑出一条完成的SQL语句
private final StringBuilder sqlBuilder = new StringBuilder();

static class ContextMap extends HashMap<String, Object> {
  private static final long serialVersionUID = 2977601501966151582L;
  //将用户传入的参数封装成MetaObject对象（类实例中检查类的属性是否包含getter,setter方法）
  private MetaObject parameterMetaObject;
  public ContextMap(MetaObject parameterMetaObject) {
    this.parameterMetaObject = parameterMetaObject;
  }

  @Override
  public Object get(Object key) {
    String strKey = (String) key;
    //如果ContextMap中已经包含了该key，则直接返回
    if (super.containsKey(strKey)) {
      return super.get(strKey);
    }
    //如果不包含该key,从parameterMetaObject中查找对应属性
    if (parameterMetaObject != null) {
      // issue #61 do not modify the context when reading
      return parameterMetaObject.getValue(strKey);
    }

    return null;
  }
}

public void appendSql(String sql) {
  sqlBuilder.append(sql);
  sqlBuilder.append(" ");
}

public void bind(String name, Object value) {
  bindings.put(name, value);
}

@Override
public boolean apply(DynamicContext context) {
  //将动态SQL（带${}占位符的SQL）解析成完成SQL语句的解析器，即将${}占位符替换成实际的变量值
  GenericTokenParser parser = createParser(new BindingTokenParser(context, injectionFilter));
  //将解析后的SQL片段添加到DynamicContext中
  context.appendSql(parser.parse(text));
  return true;
}

private DynamicContext context;

private Pattern injectionFilter; //需要匹配的正则表达式

@Override
public String handleToken(String content) {
  //获取用户提供的实参
  Object parameter = context.getBindings().get("_parameter");
  //如果实参为null
  if (parameter == null) {
    //将参考上下文的value key设为null
    context.getBindings().put("value", null);
    //如果实参是一个常用数据类型的类（Integer.class,String.class,Byte.class等等）
  } else if (SimpleTypeRegistry.isSimpleType(parameter.getClass())) {
    //将参考上下文的value key设为该实参
    context.getBindings().put("value", parameter);
  }
  //通过OGNL解析参考上下文的值
  Object value = OgnlCache.getValue(content, context.getBindings());
  String srtValue = (value == null ? "" : String.valueOf(value)); // issue #274 return "" instead of "null"
  //检测合法性
  checkInjection(srtValue);
  return srtValue;
}

private void checkInjection(String value) {
  if (injectionFilter != null && !injectionFilter.matcher(value).matches()) {
    throw new ScriptingException("Invalid input. Please conform to regex" + injectionFilter.pattern());
  }
}

@Data
@ToString
public class User {
    private int id;
    private String name;
}

public class OGNLDemo {
    public void testOgnl1() throws OgnlException {
        OgnlContext context = new OgnlContext();
        context.put("cn","China");
        String value = (String) context.get("cn");
        System.out.println(value);

        User user = new User();
        user.setId(100);
        user.setName("Jack");
        context.put("user",user);
        Object u = context.get("user");
        System.out.println(u);
        Object ognl = Ognl.parseExpression("#user.id");
        Object value1 = Ognl.getValue(ognl,context,context.getRoot());
        System.out.println(value1);

        User user1 = new User();
        user1.setId(200);
        user1.setName("Mark");
        context.setRoot(user1);
        Object ognl1 = Ognl.parseExpression("id");
        Object value2 = Ognl.getValue(ognl1,context,context.getRoot());
        System.out.println(value2);

        Object ognl2 = Ognl.parseExpression("@@floor(10.9)");
        Object value3 = Ognl.getValue(ognl2, context, context.getRoot());
        System.out.println(value3);
    }

    public static void main(String[] args) throws OgnlException {
        OGNLDemo demo = new OGNLDemo();
        demo.testOgnl1();
    }
}

private static final Map<String, Object> expressionCache = new ConcurrentHashMap<String, Object>();

public static Object getValue(String expression, Object root) {
  try {
    //创建OgnlContext对象
    Map<Object, OgnlClassResolver> context = Ognl.createDefaultContext(root, new OgnlClassResolver());
    //使用OGNL执行expression表达式
    return Ognl.getValue(parseExpression(expression), context, root);
  } catch (OgnlException e) {
    throw new BuilderException("Error evaluating expression '" + expression + "'. Cause: " + e, e);
  }
}

private static Object parseExpression(String expression) throws OgnlException {
  //查找缓存
  Object node = expressionCache.get(expression);
  if (node == null) {
    //解析表达式
    node = Ognl.parseExpression(expression);
    //将表达式的解析结果添加到缓存中
    expressionCache.put(expression, node);
  }
  return node;
}

public class StaticTextSqlNode implements SqlNode {
  private final String text;

  public StaticTextSqlNode(String text) {
    this.text = text;
  }

  @Override
  public boolean apply(DynamicContext context) {
    context.appendSql(text);
    return true;
  }

}

//用于解析<if>节点的test表达式的值
private final ExpressionEvaluator evaluator;
//记录<if>节点中test表达式
private final String test;
//记录了<if>节点的子节点
private final SqlNode contents;

@Override
public boolean apply(DynamicContext context) {
  //检测test属性中记录的表达式
  if (evaluator.evaluateBoolean(test, context.getBindings())) {
    //如果test表达式为true,则执行子节点的apply()方法
    contents.apply(context);
    return true; //返回test表达式的结果为true
  }
  return false; //返回test表达式的结果为false
}

public boolean evaluateBoolean(String expression, Object parameterObject) {
  //用OGNL解析expression表达式
  Object value = OgnlCache.getValue(expression, parameterObject);
  //处理Boolean类型
  if (value instanceof Boolean) {
    return (Boolean) value;
  }
  //处理数字类型
  if (value instanceof Number) {
    return new BigDecimal(String.valueOf(value)).compareTo(BigDecimal.ZERO) != 0;
  }
  return value != null;
}

<insert id="insertNotNullBetdetails" parameterType="com.cloud.model.game.Betdetails">
   insert into betdetails
   <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="id != null">id,</if>
      <if test="orderId != null">orderId,</if>
      <if test="actorIndex != null">actorIndex,</if>
      <if test="ballIndex != null">ballIndex,</if>
      <if test="ballValue != null">ballValue,</if>
      <if test="betAmount != null">betAmount,</if>
      <if test="createTime != null">createTime,</if>
      <if test="rate1 != null">rate1,</if>
      <if test="rate2 != null">rate2,</if>
      <if test="rate3 != null">rate3,</if>
      <if test="gameType != null">gameType,</if>
      <if test="status != null">status,</if>
      <if test="betResult != null">betResult,</if>
      <if test="awardAmount != null">awardAmount,</if>
      <if test="ballName != null">ballName,</if>
   </trim>
   <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="id != null">#{id},</if>
      <if test="orderId != null">#{orderId},</if>
      <if test="actorIndex != null">#{actorIndex},</if>
      <if test="createTime != null">#{createTime},</if>
      <if test="ballIndex != null">#{ballIndex},</if>
      <if test="ballValue != null">#{ballValue},</if>
      <if test="betAmount != null">#{betAmount},</if>
      <if test="rate1 != null">#{rate1},</if>
      <if test="rate2 != null">#{rate2},</if>
      <if test="rate3 != null">#{rate3},</if>
      <if test="gameType != null">#{gameType},</if>
      <if test="status != null">#{status},</if>
      <if test="betResult != null">#{betResult},</if>
      <if test="awardAmount != null">#{awardAmount},</if>
      <if test="ballName != null">#{ballName},</if>
   </trim>
</insert>

private final SqlNode contents; //该<trim>节点的子节点
private final String prefix; //记录了前缀字符串（为<trim>节点包裹的SQL语句添加的前缀）
private final String suffix; //记录了后缀字符串（为<trim>节点包裹的SQL语句添加的后缀）
//如果<trim>节点包裹的SQL语句是空语句，删除指定的前缀，如where
private final List<String> prefixesToOverride;
//如果<trim>节点包裹的SQL语句是空语句，删除指定的后缀，如逗号
private final List<String> suffixesToOverride;

@Override
public boolean apply(DynamicContext context) {
  //创建FilteredDynamicContext对象，FilteredDynamicContext是TrimSqlNode的内部类，继承于DynamicContext
  FilteredDynamicContext filteredDynamicContext = new FilteredDynamicContext(context);
  //调用子节点的apply()方法进行解析，注意收集SQL语句的是filteredDynamicContext
  boolean result = contents.apply(filteredDynamicContext);
  //处理前缀和后缀
  filteredDynamicContext.applyAll();
  return result;
}

private DynamicContext delegate; //底层封装委托的DynamicContext对象
private boolean prefixApplied; //是否已经处理过前缀
private boolean suffixApplied; //是否已经处理过后缀
private StringBuilder sqlBuffer; //用于记录子节点解析后的结果

public void applyAll() {
  //获取子节点解析后的结果，并全部转化为大写
  sqlBuffer = new StringBuilder(sqlBuffer.toString().trim());
  String trimmedUppercaseSql = sqlBuffer.toString().toUpperCase(Locale.ENGLISH);
  if (trimmedUppercaseSql.length() > 0) {
    //处理前缀
    applyPrefix(sqlBuffer, trimmedUppercaseSql);
    //处理后缀
    applySuffix(sqlBuffer, trimmedUppercaseSql);
  }
  //将解析后的结果SQL片段添加到DynamicContext的StringBuilder中
  delegate.appendSql(sqlBuffer.toString());
}

private void applyPrefix(StringBuilder sql, String trimmedUppercaseSql) {
  if (!prefixApplied) { //如果还没有处理过前缀
    prefixApplied = true; //更新为已处理
    if (prefixesToOverride != null) { //如果需要删除的前缀列表不为null
      //遍历该前缀列表
      for (String toRemove : prefixesToOverride) {
        //如果<trim>子节点收集上来的SQL语句以该前缀开头
        if (trimmedUppercaseSql.startsWith(toRemove)) {
          //从<trim>子节点收集上来的StringBuilder中删除该前端
          sql.delete(0, toRemove.trim().length());
          break;
        }
      }
    }
    //如果有前缀字符串（比如说"("）,将前缀字符串插入StringBuilder最前端
    if (prefix != null) {
      sql.insert(0, " ");
      sql.insert(0, prefix);
    }
  }
}

private void applySuffix(StringBuilder sql, String trimmedUppercaseSql) {
  if (!suffixApplied) { //如果还没有处理过后缀
    suffixApplied = true; //更新为已处理后缀
    if (suffixesToOverride != null) { //如果需要处理的后缀列表不为null
      //遍历该后缀列表
      for (String toRemove : suffixesToOverride) {
        //如果从<trim>子节点收集上来的SQL语句以该后缀结尾
        if (trimmedUppercaseSql.endsWith(toRemove) || trimmedUppercaseSql.endsWith(toRemove.trim())) {
          //获取该后缀的起始位置
          int start = sql.length() - toRemove.trim().length();
          //获取该后缀的终止位置
          int end = sql.length();
          //从<trim>子节点收集上来的StringBuilder中删除该后端
          sql.delete(start, end);
          break;
        }
      }
    }
    //如果有后缀字符串（比如说")"）,将前缀字符串拼接上StringBuilder最后端
    if (suffix != null) {
      sql.append(" ");
      sql.append(suffix);
    }
  }
}

public class WhereSqlNode extends TrimSqlNode {

  private static List<String> prefixList = Arrays.asList("AND ","OR ","AND\n", "OR\n", "AND\r", "OR\r", "AND\t", "OR\t");

  public WhereSqlNode(Configuration configuration, SqlNode contents) {
    super(configuration, contents, "WHERE", prefixList, null, null);
  }

}

public class SetSqlNode extends TrimSqlNode {

  private static List<String> suffixList = Arrays.asList(",");

  public SetSqlNode(Configuration configuration,SqlNode contents) {
    super(configuration, contents, "SET", null, null, suffixList);
  }

}

<insert id="insertBetdetailsByBatch" parameterType="java.util.List">
   insert into betdetails(id,orderId,actorIndex,createTime,ballIndex,ballValue,betAmount,rate1,rate2,rate3,gameType,status,betResult,awardAmount,ballName) values
   <foreach collection="list" item="item" index="index" separator=",">
      (#{item.id},#{item.orderId},#{item.actorIndex},#{item.createTime},#{item.ballIndex},#{item.ballValue},#{item.betAmount},#{item.rate1},#{item.rate2},#{item.rate3},#{item.gameType},#{item.status},#{item.betResult},#{item.awardAmount},#{item.ballName})
   </foreach>
</insert>

<select id="findAgentUserBalance" parameterType="java.util.Map" resultType="java.math.BigDecimal">
   SELECT SUM(banlance) FROM app_user
   <where>
      <if test="null != userIds">
         AND id IN
         <foreach collection="userIds" item="item" index="index" separator="," open="(" close=")">
            #{item}
         </foreach>
      </if>
   </where>
</select>

public static final String ITEM_PREFIX = "__frch_";

//用于判断循环的终止条件
private final ExpressionEvaluator evaluator;
//迭代的集合表达式
private final String collectionExpression;
//记录了该ForEachSqlNode节点的子节点
private final SqlNode contents;
//在循环开始前要添加的字符串
private final String open;
//在循环结束后要添加的字符串
private final String close;
//循环过程中，每项之间的分隔符
private final String separator;
//本次迭代的集合元素标识（相当于一个变量，用该变量来识别）
private final String item;
//本次迭代的集合索引标识（相当于一个变量，用该变量来识别）
private final String index;
//全局配置信息
private final Configuration configuration;

@Override
public boolean apply(DynamicContext context) {
  //获取用户传入的参数的上下文
  Map<String, Object> bindings = context.getBindings();
  //将参数上下文作为root传入OGNL解析出类似#{item.id}的原值后将迭代的集合表达式还原成集合本身
  final Iterable<?> iterable = evaluator.evaluateIterable(collectionExpression, bindings);
  //如果集合没有数据，直接返回true
  if (!iterable.iterator().hasNext()) {
    return true;
  }
  boolean first = true;
  //在循环开始前处理要添加的字符SQL片段
  applyOpen(context);
  int i = 0;
  //开始遍历集合，进入循环
  for (Object o : iterable) {
    //将context缓存为另一个对象
    DynamicContext oldContext = context;
    //如果是集合的第一项，或者分隔符为null
    if (first || separator == null) {
      //以空前缀来构建context为PrefixedContext对象
      context = new PrefixedContext(context, "");
    } else { //如果不是集合第一项，或者分隔符不为null,以分隔符为前缀来构建context为PrefixedContext对象
      context = new PrefixedContext(context, separator);
    }
    //获取迭代计数器
    int uniqueNumber = context.getUniqueNumber();
    // Issue #709 
    if (o instanceof Map.Entry) {
      //如果集合是Map类型，将集合中key和value添加到DynamicContext.bindings集合中保存
      @SuppressWarnings("unchecked") 
      Map.Entry<Object, Object> mapEntry = (Map.Entry<Object, Object>) o;
      applyIndex(context, mapEntry.getKey(), uniqueNumber);
      applyItem(context, mapEntry.getValue(), uniqueNumber);
    } else {
      //将集合中的索引和元素添加到DynamicContext.bindings集合中保存
      applyIndex(context, i, uniqueNumber);
      applyItem(context, o, uniqueNumber);
    }
    //调用子节点的apply()收集SQL语句，放入DynamicContext的代理类FilteredDynamicContext的StringBuilder中
    //此处解析的是类如#{_frch_index_0},#{__frch_item_0}的标识
    contents.apply(new FilteredDynamicContext(configuration, context, index, item, uniqueNumber));
    if (first) {
      //如果是第一项，将first更新为false（在applyOpen(context)中，prefixApplied已经被更新为true）
      first = !((PrefixedContext) context).isPrefixApplied();
    }
    //还原context为原始DynamicContext，重新进入下一项循环
    context = oldContext;
    i++;
  }
  //在循环结束后添加要处理的SQL片段
  applyClose(context);
  context.getBindings().remove(item);
  context.getBindings().remove(index);
  return true;
}

private void applyOpen(DynamicContext context) {
  if (open != null) {
    //将开始循环前的SQL片段添加到DynamicContext的StringBuilder中
    context.appendSql(open);
  }
}

private void applyIndex(DynamicContext context, Object o, int i) {
  if (index != null) {
    //将集合的索引标识与放入的对象（map对象放入的是key,List对象放入的是真正的索引值）存入参考上下文中
    //以上面配置的Map为例，假如传入的userIds为("小李飞刀",1),("霸天虎",2)，此处假设用户名不能重复，且执行到第一个
    //此处存入的是("index","小李飞刀")，如果执行到第二个的时候，此处存入的是("index","霸天虎")
    context.bind(index, o);
    //将集合的索引标识与计数器的连接绑定，与放入的对象存入参考上下文中
    //此处存入的是("_frch_index_0","小李飞刀")，执行到第二个的时候，此处存入的是("_frch_index_1","霸天虎")
    context.bind(itemizeItem(index, i), o);
  }
}

private static String itemizeItem(String item, int i) {
  //返回的值类似为__frch_item_0（假设item="item",i=0）
  return new StringBuilder(ITEM_PREFIX).append(item).append("_").append(i).toString();
}

private void applyItem(DynamicContext context, Object o, int i) {
  if (item != null) {
    //将集合的内容标识与放入的对象（map对象放入的为value，List对象放入的为列表中的对象元素）存入参考上下文中
    //对应索引的内容，此处存入的是("item",1)，执行到第二个的时候，此处存入的是("item",2)
    context.bind(item, o);
    //将集合的内容标识与计数器的连接绑定，与放入的对象存入参考上下文中,为子节点的进一步解析（真正替换每一次迭代项为集合实际的值）做准备
    //此处存入的是("__frch_item_0",1)，执行到第二个的时候，此处存入的是("__frch_item_1",2)
    context.bind(itemizeItem(item, i), o);
  }
}

private void applyClose(DynamicContext context) {
  if (close != null) {
    //将结束循环后的SQL片段添加到DynamicContext的StringBuilder中
    context.appendSql(close);
  }
}

private final DynamicContext delegate; //对DynamicContext的委托
private final String prefix; //指定的前缀
private boolean prefixApplied; //是否已经处理过前缀

@Override
public void appendSql(String sql) {
  //如果没有处理过前缀且要添加的SQL语句不为空
  if (!prefixApplied && sql != null && sql.trim().length() > 0) {
    //先把指定的前缀SQL片段添加到delegate中
    delegate.appendSql(prefix);
    //修改为前缀已处理
    prefixApplied = true;
  }
  //再把处理完的SQL语句片段添加到StringBuilder中
  delegate.appendSql(sql);
}

private final DynamicContext delegate; //委托的DynamicContext
private final int index; //对应集合项在集合中的索引位置
private final String itemIndex; //对应集合项的index（索引标识）
private final String item; //对应集合项的item（元素标识）

@Override
public void appendSql(String sql) {
  //解析类如("_frch_index_0","小李飞刀")，("__frch_item_0",1)的映射，给_frch_index_0，__frch_item_0变为OGNL可以识别的
  //#{_frch_index_0},#{__frch_item_0}
  GenericTokenParser parser = new GenericTokenParser("#{", "}", new TokenHandler() {
    @Override
    public String handleToken(String content) {
      String newContent = content.replaceFirst("^\\s*" + item + "(?![^.,:\\s])", itemizeItem(item, index));
      if (itemIndex != null && newContent.equals(content)) {
        newContent = content.replaceFirst("^\\s*" + itemIndex + "(?![^.,:\\s])", itemizeItem(itemIndex, index));
      }
      return new StringBuilder("#{").append(newContent).append("}").toString();
    }
  });
  //通过OGNL来进行解析成对应映射的值
  delegate.appendSql(parser.parse(sql));
}

public interface Collection<E> extends Iterable<E>

public Iterable<?> evaluateIterable(String expression, Object parameterObject) {
  //使用OGNL来解析expression
  Object value = OgnlCache.getValue(expression, parameterObject);
  if (value == null) {
    throw new BuilderException("The expression '" + expression + "' evaluated to a null value.");
  }
  //处理可迭代集合类型
  if (value instanceof Iterable) {
    return (Iterable<?>) value;
  }
  //处理数组类型，转化为List,并返回该List
  if (value.getClass().isArray()) {
      // the array may be primitive, so Arrays.asList() may throw
      // a ClassCastException (issue 209).  Do the work manually
      // Curse primitives! :) (JGB)
      int size = Array.getLength(value);
      List<Object> answer = new ArrayList<Object>();
      for (int i = 0; i < size; i++) {
          Object o = Array.get(value, i);
          answer.add(o);
      }
      return answer;
  }
  //处理Map类型，返回Map的entrySet集合（Set）
  if (value instanceof Map) {
    return ((Map) value).entrySet();
  }
  throw new BuilderException("Error evaluating expression '" + expression + "'.  Return value (" + value + ") was not iterable.");
}

<select id="findList" parameterType="java.util.Map" resultType="com.cloud.model.user.AppUser">
   SELECT a.id,a.username,a.password,a.nickname,a.headImgUrl,a.phone,a.sex,a.enabled,a.type,a.createTime,a.updateTime,a.banlance,a.control,a.win,a.loginTime
   FROM app_user a
   <if test="groupId != null">
      <choose>
         <when test="groupId != 0">
            INNER JOIN user_group b ON a.id=b.user_id AND b.group_id=#{groupId}
         </when>
         <otherwise>
            LEFT JOIN user_group b ON a.id=b.user_id
         </otherwise>
      </choose>
   </if>
</select>

private final SqlNode defaultSqlNode; //<otherwise>节点对应的SqlNode
private final List<SqlNode> ifSqlNodes; //<when>节点对应的IfSqlNode集合

@Override
public boolean apply(DynamicContext context) {
  //遍历IfSqlNodes集合，并调用其中SqlNode对象的apply()方法
  for (SqlNode sqlNode : ifSqlNodes) {
    if (sqlNode.apply(context)) {
      return true;
    }
  }
  //调用defaultSqlNode.apply()方法
  if (defaultSqlNode != null) {
    defaultSqlNode.apply(context);
    return true;
  }
  return false;
}

<if test="userNarne != null and userNarne != ' '">
  and user name like concat('毛',#{userNarne},'毡')
</if>

<if test="userName != null and userName !=' '"> 
   <bind name="userNarneLike" value="'毛' + userName + '毡'"/>
     and user name like #{userNarneLike} 
</if>

private final String name; //<bind>节点名称
private final String expression; //<bind>节点的value表达式

@Override
public boolean apply(DynamicContext context) {
  //解析OGNL表达式的值
  final Object value = OgnlCache.getValue(expression, context.getBindings());
  //将name,value存入DynamicContext的bindings集合中，提供其他SqlNode的下一步解析
  context.bind(name, value);
  return true;
}