fix(engine/mysql): Support nullable fields in joins for MySQL engine (#1249)

* Fix nullable fields in joins for MySQL engine

Author: timstudd

examples/booktest/mysql/db_test.go

@@ -1,3 +1,4 @@
+//go:build examples
 // +build examples
 
 package booktest
@@ -150,7 +151,7 @@ func TestBooks(t *testing.T) {
 		t.Fatal(err)
 	}
 	for _, ab := range res {
-		t.Logf("Book %d: '%s', Author: '%s', ISBN: '%s' Tags: '%v'\n", ab.BookID, ab.Title, ab.Name, ab.Isbn, ab.Tags)
+		t.Logf("Book %d: '%s', Author: '%s', ISBN: '%s' Tags: '%v'\n", ab.BookID, ab.Title, ab.Name.String, ab.Isbn, ab.Tags)
 	}
 
 	// TODO: call say_hello(varchar)

examples/booktest/mysql/query.sql.go

@@ -22,7 +22,7 @@ WHERE tags = ?
 data class BooksByTagsRow (
   val bookId: Int,
   val title: String,
-  val name: String,
+  val name: String?,
   val isbn: String,
   val tags: String
 )

examples/kotlin/src/main/kotlin/com/example/booktest/mysql/QueriesImpl.kt

@@ -302,7 +302,14 @@ func isTableRequired(n ast.Node, tableName string, prior int) int {
 		case ast.JoinTypeFull:
 			return helper(tableOptional, tableOptional)
 		}
+	case *ast.List:
+		for _, item := range n.Items {
+			if res := isTableRequired(item, tableName, prior); res != tableNotFound {
+				return res
+			}
+		}
 	}
+
 	return tableNotFound
 }
 

internal/compiler/output_columns.go

@@ -1,4 +1,4 @@
---- https://github.com/kyleconroy/sqlc/issues/604
+-- https://github.com/kyleconroy/sqlc/issues/604
 CREATE TABLE users (
   user_id    INT PRIMARY KEY,
   city_id    INT -- nullable
@@ -23,7 +23,8 @@ INNER JOIN mayors USING (mayor_id);
 -- name: GetMayorsOptional :many
 SELECT
     user_id,
+    cities.city_id,
     mayors.full_name
 FROM users
 LEFT JOIN cities USING (city_id)
-LEFT JOIN mayors USING (mayor_id);
+LEFT JOIN mayors USING (mayor_id);

internal/endtoend/testdata/join_full/mysql/go/db.go

@@ -3,7 +3,7 @@
   "packages": [
     {
       "path": "go",
-      "engine": "postgresql",
+      "engine": "mysql",
       "name": "querytest",
       "schema": "query.sql",
       "queries": "query.sql"

internal/endtoend/testdata/join_full/mysql/go/models.go

@@ -5,4 +5,4 @@ CREATE TABLE bar (id serial not null);
 SELECT f.id, f.bar_id, b.id
 FROM foo f
 RIGHT JOIN bar b ON b.id = f.bar_id
-WHERE f.id = $1;
+WHERE f.id = ?;

internal/endtoend/testdata/join_full/mysql/go/query.sql.go

@@ -3,7 +3,7 @@
   "packages": [
     {
       "path": "go",
-      "engine": "postgresql",
+      "engine": "mysql",
       "name": "querytest",
       "schema": "query.sql",
       "queries": "query.sql"

internal/endtoend/testdata/join_full/mysql/query.sql

@@ -849,11 +849,18 @@ func (c *cc) convertJoin(n *pcast.Join) *ast.List {
 		return &ast.List{}
 	}
 	if n.Right != nil && n.Left != nil {
+		// MySQL doesn't have a FULL join type
+		joinType := ast.JoinType(n.Tp)
+		if joinType >= ast.JoinTypeFull {
+			joinType++
+		}
+
 		return &ast.List{
 			Items: []ast.Node{&ast.JoinExpr{
-				Larg:  c.convert(n.Left),
-				Rarg:  c.convert(n.Right),
-				Quals: c.convert(n.On),
+				Jointype: joinType,
+				Larg:     c.convert(n.Left),
+				Rarg:     c.convert(n.Right),
+				Quals:    c.convert(n.On),
 			}},
 		}
 	}