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get_table_from_key [2013/08/06 18:08] admin |
get_table_from_key [2013/08/09 20:27] 127.0.0.1 external edit |
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| ===== Notes ===== | ===== Notes ===== | ||
| - | This functor retrives all elements corresponding to the given tuple of keys in the input table. For example, given the table below | + | This functor retrieves all elements corresponding to the given tuple of keys in the input table. |
| + | |||
| + | **Example 1:** | ||
| + | |||
| + | Given the table below | ||
| ^ Key1* ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ^ Key1* ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ||
| Line 31: | Line 35: | ||
| | 2 | "d" | 22 | 12 | "dddd" | 12 | | | 2 | "d" | 22 | 12 | "dddd" | 12 | | ||
| - | retrieving the sub-table corresponding to the tuple of keys ''<2, "a">'' | + | retrieving the sub-table corresponding to the tuple of keys ''<2, "a">'', where 2 corresponds to column "Key1" and "a" corresponds to column "Key2", |
| ^ Key1* ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ^ Key1* ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ||
| Line 40: | Line 44: | ||
| | 2 | "d" | 22 | 12 | "dddd" | 12 | | 2 | "d" | 22 | 12 | "dddd" | 12 | ||
| - | yelds | + | results in |
| ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ||
| Line 46: | Line 50: | ||
| |@green: 22 |@green: 12 |@green: "aaaa" |@green: 23 | | |@green: 22 |@green: 12 |@green: "aaaa" |@green: 23 | | ||
| - | and retriving the sub-table corresponding to the tuple of keys ''<2>'': | + | **Example 2:** |
| + | |||
| + | Retrieving the sub-table corresponding to the tuple of keys ''<2>'', where 2 corresponds to column "Key1", | ||
| ^ Key1* ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ^ Key1* ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ||
| Line 55: | Line 61: | ||
| |@lightgreen: 2 |@green: "d" |@green: 22 |@green: 12 |@green: "dddd" |@green: 12 | | |@lightgreen: 2 |@green: "d" |@green: 22 |@green: 12 |@green: "dddd" |@green: 12 | | ||
| - | yelds | + | results in |
| ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ^ Key2* ^ Key3* ^ Value1 ^ Value2 ^ Value3 ^ | ||
| Line 63: | Line 69: | ||
| If the resulting sub-table does not have at least one column of keys or if the given tuple of keys is not present in the input table, an error is reported. | If the resulting sub-table does not have at least one column of keys or if the given tuple of keys is not present in the input table, an error is reported. | ||
| + | |||
| + | It is not possible to retrieve a sub-table indexed by keys from arbitrary key columns. For example, in the example above, it is not possible to retrieve a sub-table corresponding to keys ''<2, 22>'', where 2 corresponds to the first column ("Key1") and 22 corresponds to the third column ("Key3"). To do this, first reorder the key columns using the [[Reorder Table Column]] functor. | ||
| ===== Internal Name ===== | ===== Internal Name ===== | ||