update

clauses/when_matched.go

@@ -0,0 +1,39 @@
+package clauses
+
+import (
+	"gorm.io/gorm/clause"
+)
+
+type WhenMatched struct {
+	clause.Set
+	Where, Delete clause.Where
+}
+
+func (w WhenMatched) Name() string {
+	return "WHEN MATCHED"
+}
+
+func (w WhenMatched) Build(builder clause.Builder) {
+	if len(w.Set) > 0 {
+		builder.WriteString(" THEN")
+		builder.WriteString(" UPDATE ")
+		builder.WriteString(w.Name())
+		builder.WriteByte(' ')
+		w.Build(builder)
+
+		buildWhere := func(where clause.Where) {
+			builder.WriteString(where.Name())
+			builder.WriteByte(' ')
+			where.Build(builder)
+		}
+
+		if len(w.Where.Exprs) > 0 {
+			buildWhere(w.Where)
+		}
+
+		if len(w.Delete.Exprs) > 0 {
+			builder.WriteString(" DELETE ")
+			buildWhere(w.Delete)
+		}
+	}
+}