Removal of Components: drop
Syntax
op [ drop comp {, comp }* ]
Input parameters
op |
the operand |
comp |
a Component to drop |
Examples of valid syntaxes
DS_1 [ drop Me_2, Me_3 ]
Semantics for scalar operations
This operator cannot be applied to scalar values.
Input parameters type
op
dataset
comp
name<component>
Result type
result
dataset
Additional Constraints
All the Components comp must belong to the input Data Set op.
The Components comp cannot be Identifiers in op.
Behaviour
The operator takes as input a Data Set (op) and some Component names of such a Data Set (comp). These Components can be Measures or Attributes of op but not Identifiers. The operator drops the specified Components and maintains all the other Components of the Data Set. This operation corresponds to a projection in the usual relational join semantics (specifying which columns will be projected out).
Examples
Given the Data Set DS_1:
Input DS_1 (see structure)
Id_1 |
Id_2 |
Id_3 |
Me_1 |
At_1 |
|---|---|---|---|---|
2010 |
A |
XX |
20 |
E |
2010 |
A |
YY |
4 |
F |
2010 |
B |
XX |
9 |
F |
Example 1
DS_r := DS_1 [ drop At_1 ];
results in (see structure):
Id_1 |
Id_2 |
Id_3 |
Me_1 |
|---|---|---|---|
2010 |
A |
XX |
20 |
2010 |
A |
YY |
4 |
2010 |
B |
XX |
9 |