third

Author: JPryce-Aklundh

modules/ROOT/pages/expressions/string-operators.adoc

@@ -1,35 +1,129 @@
-= String operators
+= String concatenation operators
 :description: Information about Cypher's string operators.
 :table-caption!:
 
-Cypher contains two functionally equivalent operators for the concatenation of `STRING` values:
+Cypher contains two operators for the concatenation of `STRING` values:
 
-* `+`
 * `||`
+* `+`
 
-`||` is xref:appendix/gql-conformance/index.adoc[GQL conformant], `+` is not.
+The two operators are functionally equivalent.
+However, `||` is xref:appendix/gql-conformance/index.adoc[GQL conformant], while `+` is not.
 
-For additional expressions evaluating `STRING` values, see xref:functions/string.adoc[String functions].
+For additional expressions that evaluate `STRING` values, see xref:functions/string.adoc[String functions].
 
 [[examples]]
 == Examples
 
 .`||` and `+`
 [source, cypher]
 ----
-RETURN 'concatenatedWith' || '||' AS result1
-       'concatenatedWith' + '+' AS result2
+RETURN 'Neo' || '4j' AS result1
+       'Neo' + '4j' AS result2
 ----
 
 .Result
 [role="queryresult",options="header,footer",cols="2*<m"]
 |===
 | result1 | result2
 
-| "concatenatedWith||" | "concatenatedWith+"
+| "Neo4j" | "Neo4j"
 
 2+d|Rows: 1
 |===
 
+The xref:functions/string.adoc#functions-tostring[`toString()`] function can be used to concatenate non-`STRING` values into a `STRING` value.
+
+.Concatenation using `toString()` function
+[source, cypher]
+----
+RETURN 'The number is: ' || toString(42) AS result
+----
+
+.Result
+[role="queryresult",options="header,footer",cols="1*<m"]
+|===
+| result
+
+| "The number is: 42"
+
+1+d| Rows: 1
+|===
+
+Cypher does not insert spaces when concatenating `STRING` values.
+
+.Adding whitespaces in `STRING` concatenation
+[source, cypher]
+----
+RETURN 'Alpha' || 'Beta' AS result1, 
+       'Alpha' || ' ' || 'Beta' AS result2
+----
+
+.Result
+[role="queryresult",options="header,footer",cols="2*<m"]
+|===
+| result1 | result2
+
+| "AlphaBeta" | "Alpha Beta"
+
+1+d| Rows: 1
+|===
+
+.Concatenating `STRING` properties
+[source, cypher]
+----
+CREATE (p:Person {firstName: 'Keanu', lastName: 'Reeves'})
+SET p.fullName = p.firstName || ' ' || p.lastName
+RETURN p.fullName AS fullName
+----
+
+.Result
+[role="queryresult",options="header,footer",cols="1*<m"]
+|===
+| fullName
+
+| "Keanu Reeves"
+
+1+d| Rows: 1
+|===
+
+`STRING` values in a `LIST` can be concatenated using the xref:functions/list.adoc#functions-reduce[`reduce()`] function.
+
+.Concatenate `STRING` values in a `LIST`
+[source, cypher]
+----
+RETURN reduce(acc = '', item IN ['Neo', '4j'] | acc + item) AS result
+----
+
+.Result
+[role="queryresult",options="header,footer",cols="1*<m"]
+|===
+| result
+
+| "Neo4j"
+
+1+d| Rows: 1
+|===
+
+Concatenating a `STRING` value with `NULL` returns `NULL`.
+To skip the first `NULL` value in a list of expressions, use the xref:functions/scalar.adoc#functions-coalesce[`coalesce()`] function.
+
+In the following example, `coalesce()` is used with `reduce()` to replace each `NULL` value in the `LIST` with an empty `STRING` (`''`).
+This ensures that all `NULL` values are effectively skipped, allowing the `reduce()` function to concatenate the remaining `STRING` values.
+
+.Using `reduce()` and `coalesce()` to skip `NULL` values when concatenating a `LIST`
+[source, cypher]
+----
+WITH ['Neo', NULL, '4j', NULL, 'Hello', NULL] AS items
+RETURN reduce(acc = '', item IN items | acc + coalesce(item, '')) AS result
+----
+
+.Result
+[role="queryresult",options="header,footer",cols="1*<m"]
+|===
+| result
 
+| "Neo4jHello"
 
+1+d| Rows: 1
+|===