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Update 解析

如果一個Record 是Update語句，那麼這個Record的操作類型為UPDATE。

update更新前的字段存儲在：Record.getFieldList()中索引為偶數的Field，更新後的字段值存儲在：索引為奇數的Field。

下麵的示例代碼介紹當update的表有主鍵時，獲取Insert完整語句的代碼示例：

StringBuilder update_string=new StringBuilder();                   
Record.Type type=record.getOpt();
DataMessage.Record.Field field;
StringBuilder SetValue = new StringBuilder();
StringBuilder WhereCondition = new StringBuilder();
String ConditionStr;
boolean hasPk=false;
boolean pkMode=false;
boolean hasSet=false;
if(type.equals(Record.Type.UPDATE)){                        
    int i=0;
    DataMessage.Record.Field OldField = null;
    DataMessage.Record.Field NewField = null;
    List<DataMessage.Record.Field> fields = record.getFieldList();
    for (; i <fields.size() ; i++) {
        if (i % 2 == 0) {
            OldField = fields.get(i);
            continue;
        }
    NewField = fields.get(i);
    if (field.isPrimary()) {
        if (hasPk) {
            WhereCondition.append(" and ");
        }
        //where old value
        ConditionStr = getFieldValue(OldField);
        if(ConditionStr==null){                                         WhereCondition.append("`"+field.getFieldname().toLowerCase()+"`" + " " + "is null");
        }else{
               WhereCondition.append("`"+field.getFieldname().toLowerCase()+"`"+" = "+ NewField.getValue());                       
         }
        hasPk = true;
    }
    if (hasSet) {
        SetValue.append(COMMA);
    }
      SetValue.append("`"+field.getFieldname().toLowerCase()+"`" + " = " + field.getValue());
    String setStr = getFieldValue(field);
    hasSet = true;
    }
    update_string.append("Update "+record.getTablename() +" Set " + SetValue + " Where "+WhereCondition +";");                        
}

StringBuilder delete_string=new StringBuilder();                   
Record.Type type=record.getOpt();
DataMessage.Record.Field field;
StringBuilder FieldName=new StringBuilder();
StringBuilder FieldValue = new StringBuilder();
StringBuilder DeleteCondition = new StringBuilder();
boolean hasPk=false;
boolean pkMode=false;
if(type.equals(Record.Type.DELETE)){
   int i=0;
   List<DataMessage.Record.Field> fields = record.getFieldList();                     
   delete_string.append("Delete From" + record.getTablename() + "where");                         
   // 表是否有主鍵？
   if (record.getPrimaryKeys() != null) {
             pkMode = record.getPrimaryKeys().length() > 0 ? true : false;
   }                        
   for (; i < fields.size(); i++) {
            if ((pkMode && !field.isPrimary())) {
                    continue;
            }
            if (hasPk) {
                    delete_string.append(" and ");
            }
            delete_string.append(field.getFieldname() + "=" + field.getValue());
            hasPk = true;
    }
    delete_string.append(";");
}

StringBuilder sql_string = new StringBuilder();
Record.Type type = record.getOpt();
if(type.equals(Record.Type.BEGIN)){
        sql_string.append("Begin");
}

StringBuilder sql_string = new StringBuilder();
Record.Type type = record.getOpt();
if(type.equals(Record.Type.COMMIT)){
        sql_string.append("commit");
}