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v4.3
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    v4.3

      ifnull()

      Function ifnull() returns the left-most non null value from two values, or returns null if both values are null.

      When two values are of different data structures, data conversion might be triggered to guarantee a consistent data type in the final column.

      Occasions when null value is produced: properties not provided when inserting data, properties created after data is inserted, calling a property that is not existent.

      Arguments:

      • Value1 <any>
      • Value2 <any>

      Returns:

      • Result <any>

      Sample graph: (to be used for the following examples)

      Run below UQLs one by one in an empty graphset to create graph data:
      create().node_property(@default, "name").node_property(@default, "try1", int32).node_property(@default, "try2", int32).node_property(@default, "try3", int32)
      insert().into(@default).nodes([{name:"Jason", try1:84}, {name:"Alice", try1:55, try2:79}, {name:"Lina"}, {name:"Eric", try1:39, try2:46, try3:61}, {name:"Pepe", try1:89}])
      

      Comman Usage

      Example: Return the score of the last re-test that each student takes, knowing that each student has three chances, and retesting is allowed only if the previous one failed. Return null if a student does not give any try.

      find().nodes() as n
      return table(n.name, ifnull(n.try3, n.try2))
      

      | n.name | ifnull(n.try3, n.try2) |
      |--------|------------------------|
      | Jason  | null                   |
      | Alice  | 79                     |
      | Lina   | null                   |
      | Eric   | 61                     |
      | Pepe   | null                   |
      
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