The query interface order method replaces any previously applied or…

…dering (see #85)

GRDB/QueryInterface/QueryInterfaceRequest.swift

@@ -189,7 +189,7 @@ extension QueryInterfaceRequest {
     @warn_unused_result
     public func order(orderings: [_SQLOrdering]) -> QueryInterfaceRequest<T> {
         var query = self.query
-        query.orderings.appendContentsOf(orderings)
+        query.orderings = orderings
         return QueryInterfaceRequest(query: query)
     }
 

README.md

@@ -2182,6 +2182,13 @@ All the methods above return another request, which you can further refine by ap
     // SELECT * FROM "persons" ORDER BY "score" DESC, "name"
     Person.order(scoreColumn.desc, nameColumn)
     ```
+
+    Each `order` call clears any previous ordering:
+
+    ```swift
+    // SELECT * FROM "persons" ORDER BY "name"
+    Person.order(scoreColumn).order(nameColumn)
+    ```
 
 - `reverse()` reverses the eventual orderings.
 
@@ -2214,13 +2221,14 @@ You can refine requests by chaining those methods:
 Person.order(nameColumn).filter(emailColumn != nil)
 ```
 
-The `select`, `group` and `limit` methods ignore and replace previously applied selection, grouping and limits. On the opposite, `filter`, `having`, and `order` methods extend the query:
+The `select`, `order`, `group`, and `limit` methods ignore and replace previously applied selection, orderings, grouping, and limits. On the opposite, `filter`, and `having` methods extend the query:
 
 ```swift
 Person                          // SELECT * FROM "persons"
     .filter(nameColumn != nil)  // WHERE (("name" IS NOT NULL)
     .filter(emailColumn != nil) //        AND ("email IS NOT NULL"))
-    .order(nameColumn)          // ORDER BY "name"
+    .order(nameColumn)          // - ignored -
+    .order(ageColumn)           // ORDER BY "age"
     .limit(20, offset: 40)      // - ignored -
     .limit(10)                  // LIMIT 10
 ```

Tests/Public/QueryInterfaceRequest/QueryInterfaceRequestTests.swift

@@ -415,7 +415,7 @@ class QueryInterfaceRequestTests: GRDBTestCase {
         let dbQueue = try! makeDatabaseQueue()
         XCTAssertEqual(
             sql(dbQueue, tableRequest.order(Col.age).order(Col.name)),
-            "SELECT * FROM \"readers\" ORDER BY \"age\", \"name\"")
+            "SELECT * FROM \"readers\" ORDER BY \"name\"")
     }
 
 
@@ -462,7 +462,7 @@ class QueryInterfaceRequestTests: GRDBTestCase {
             sql(dbQueue, tableRequest.reverse().reverse()),
             "SELECT * FROM \"readers\"")
         XCTAssertEqual(
-            sql(dbQueue, tableRequest.order(Col.age).order(Col.name).reverse().reverse()),
+            sql(dbQueue, tableRequest.order(Col.age, Col.name).reverse().reverse()),
             "SELECT * FROM \"readers\" ORDER BY \"age\", \"name\"")
     }
 

Tests/Public/QueryInterfaceRequest/TableMapping+QueryInterfaceRequestTests.swift

@@ -254,7 +254,7 @@ class TableMappingQueryInterfaceRequestTests: GRDBTestCase {
         let dbQueue = try! makeDatabaseQueue()
         XCTAssertEqual(
             sql(dbQueue, Reader.order(Col.age).order(Col.name)),
-            "SELECT * FROM \"readers\" ORDER BY \"age\", \"name\"")
+            "SELECT * FROM \"readers\" ORDER BY \"name\"")
     }