Fix bug in ToManySetOpsAdd and impure join tables

- This is a bug that manifests itself a bunch with our update code where
  you cannot actually use the update method to update a key since it
  uses the values on the struct to both update the values and find the
  object to update but in this operation the key must have two different
  values.

templates/12_relationship_to_many_setops.tpl

@@ -6,27 +6,47 @@
 		{{- $txt := txtsFromToMany $dot.Tables $table . -}}
 		{{- $varNameSingular := .Table | singular | camelCase -}}
 		{{- $foreignVarNameSingular := .ForeignTable | singular | camelCase}}
+		{{- $foreignPKeyCols := (getTable $dot.Tables .ForeignTable).PKey.Columns -}}
+		{{- $foreignSchemaTable := .ForeignTable | $dot.SchemaTable}}
 // Add{{$txt.Function.Name}} adds the given related objects to the existing relationships
 // of the {{$table.Name | singular}}, optionally inserting them as new records.
 // Appends related to o.R.{{$txt.Function.Name}}.
 // Sets related.R.{{$txt.Function.ForeignName}} appropriately.
 func (o *{{$txt.LocalTable.NameGo}}) Add{{$txt.Function.Name}}(exec boil.Executor, insert bool, related ...*{{$txt.ForeignTable.NameGo}}) error {
 	var err error
 	for _, rel := range related {
-		{{if not .ToJoinTable -}}
-		rel.{{$txt.Function.ForeignAssignment}} = o.{{$txt.Function.LocalAssignment}}
-			{{if .ForeignColumnNullable -}}
-		rel.{{$txt.ForeignTable.ColumnNameGo}}.Valid = true
-			{{end -}}
-		{{end -}}
 		if insert {
+			{{if not .ToJoinTable -}}
+			rel.{{$txt.Function.ForeignAssignment}} = o.{{$txt.Function.LocalAssignment}}
+				{{if .ForeignColumnNullable -}}
+			rel.{{$txt.ForeignTable.ColumnNameGo}}.Valid = true
+				{{end -}}
+			{{end -}}
+
 			if err = rel.Insert(exec); err != nil {
 				return errors.Wrap(err, "failed to insert into foreign table")
 			}
 		}{{if not .ToJoinTable}} else {
-			if err = rel.Update(exec, "{{.ForeignColumn}}"); err != nil {
+			updateQuery := fmt.Sprintf(
+				"UPDATE {{$foreignSchemaTable}} SET %s WHERE %s",
+				strmangle.SetParamNames("{{$dot.LQ}}", "{{$dot.RQ}}", {{if $dot.Dialect.IndexPlaceholders}}1{{else}}0{{end}}, []string{{"{"}}"{{.ForeignColumn}}"{{"}"}}),
+				strmangle.WhereClause("{{$dot.LQ}}", "{{$dot.RQ}}", {{if $dot.Dialect.IndexPlaceholders}}2{{else}}0{{end}}, {{$foreignVarNameSingular}}PrimaryKeyColumns),
+			)
+			values := []interface{}{o.{{$txt.LocalTable.ColumnNameGo}}, rel.{{$foreignPKeyCols | stringMap $dot.StringFuncs.titleCase | join ", rel."}}{{"}"}}
+
+			if boil.DebugMode {
+				fmt.Fprintln(boil.DebugWriter, updateQuery)
+				fmt.Fprintln(boil.DebugWriter, values)
+			}
+
+			if _, err = exec.Exec(updateQuery, values...); err != nil {
 				return errors.Wrap(err, "failed to update foreign table")
 			}
+
+			rel.{{$txt.Function.ForeignAssignment}} = o.{{$txt.Function.LocalAssignment}}
+			{{if .ForeignColumnNullable -}}
+			rel.{{$txt.ForeignTable.ColumnNameGo}}.Valid = true
+			{{end -}}
 		}{{end -}}
 	}