根据列值重复行次数

Question

我的桌子看起来像这样：

| name |  start_date   |  duration_day|
========================================
|   A  |  2015-01-01   |       3      |
|   B  |  2015-01-02   |       2      |

现在我想得到一个这样的输出：

   | name |     date   |
   =====================
   |  A   | 2015-01-01 |
   |  A   | 2015-01-02 |
   |  A   | 2015-01-03 |
   |  B   | 2015-01-02 |
   |  B   | 2015-01-03 |

我如何在PostgreSQL中执行此操作？

Answer 1

借用Abelisto's answer，您可以在行{s}}中使用duration_day generate_series()生成duration_day值的系列。该函数使用my_table中的SELECT name, start_date + n AS date FROM my_table, generate_series(0, duration_day - 1) AS x(n); 值到隐式table function。

<select class="form-control" name="companyinternaltier" 
ng-required="true" ng-model="companyData.InternalTierId" 
ng-options="item.Id as item.Name for item in lookUps.internalTier">          
<option value="">- Select Internal Tier Level -</option>

Answer 2

select
  name, 
  start_date + generate_series(0, duration_day - 1)
from
  your_table;