Join two tables (left, right) basd on a matching input field (
right.lookupField) and add a
fetchField column to the first (left) table. This operator is useful if the input table has numerous columns, which can make it difficult to use a simple join.
lookupOperator(table, inputField, lookupTable, lookupField, fetchField)
table: Input table.
inputField: Column to be matched in the input table.
lookupTable: Name of the lookup table.
lookupField: Column to be matched in the lookup table.
fetchField: Column in lookup table to add to input table.
The output table is the same as input table with an additional column named
fetchField. If a
fetchField column already exists in the input table the original one is dropped.
table A with (f1, f2, f3) columns,
B = select f1 as u1, SIZE(f2) + SIZE(f3) as val from A C = lookupOperator(A,"f1", B, "u1", "val") -- C should be a table A with additional "val" column -- The operator should produce the same output as -- select f1, f2, f3, val from A join B on A.f1 = B.u1
Updated almost 3 years ago