Add From support for UpdateBuilder

README.md

@@ -203,6 +203,26 @@ fmt.Println(ub)
 // UPDATE users SET level = level + ? WHERE id = ?
 ```
 
+### Build `UPDATE ... FROM`
+
+`UpdateBuilder.From` emits a `FROM` clause for PostgreSQL, SQLite, and SQLServer flavors (it is ignored by other flavors). When a CTE includes tables created with `CTETable`, those table names are emitted before any explicit `From(...)` tables.
+
+```go
+ub := PostgreSQL.NewUpdateBuilder()
+ub.Update("users")
+ub.Set(ub.Assign("name", "Huan Du"))
+ub.From("people")
+ub.Where("users.person_id = people.id")
+
+sql, args := ub.Build()
+fmt.Println(sql)
+fmt.Println(args)
+
+// Output:
+// UPDATE users SET name = $1 FROM people WHERE users.person_id = people.id
+// [Huan Du]
+```
+
 Refer to the [WhereClause](https://pkg.go.dev/github.com/huandu/go-sqlbuilder#WhereClause) examples to learn its usage.
 
 ### Build `ORDER BY` clause

update.go

@@ -15,6 +15,7 @@ const (
 	updateMarkerAfterWith
 	updateMarkerAfterUpdate
 	updateMarkerAfterSet
+	updateMarkerAfterFrom
 	updateMarkerAfterWhere
 	updateMarkerAfterOrderBy
 	updateMarkerAfterLimit
@@ -71,6 +72,7 @@ type UpdateBuilder struct {
 	cteBuilder    *CTEBuilder
 
 	tables      []string
+	fromTables  []string
 	assignments []string
 	orderByCols []string
 	order       string
@@ -140,6 +142,13 @@ func (ub *UpdateBuilder) SetMore(assignment ...string) *UpdateBuilder {
 	return ub
 }
 
+// From sets table names of FROM in UPDATE.
+func (ub *UpdateBuilder) From(table ...string) *UpdateBuilder {
+	ub.fromTables = table
+	ub.marker = updateMarkerAfterFrom
+	return ub
+}
+
 // Where adds expressions to the WHERE clause in UPDATE.
 //
 // Multiple calls to Where will join expressions with AND.
@@ -339,7 +348,7 @@ func (ub *UpdateBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 			buf.WriteStringsPrefixed("INSERTED.", ub.returning, ", ")
 		}
 
-		ub.injection.WriteTo(buf, insertMarkerAfterReturning)
+		ub.injection.WriteTo(buf, updateMarkerAfterReturning)
 	}
 
 	if flavor != MySQL {
@@ -354,6 +363,20 @@ func (ub *UpdateBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 		}
 	}
 
+	if flavor == PostgreSQL || flavor == SQLite || flavor == SQLServer {
+		if len(ub.fromTables) > 0 {
+
+			if ub.cteBuilder == nil || len(ub.cteBuilder.tableNamesForFrom()) == 0 {
+				buf.WriteLeadingString("FROM ")
+			} else {
+				buf.WriteString(", ")
+			}
+
+			buf.WriteStrings(ub.fromTables, ", ")
+			ub.injection.WriteTo(buf, updateMarkerAfterFrom)
+		}
+	}
+
 	if ub.WhereClause != nil {
 		ub.whereClauseProxy.WhereClause = ub.WhereClause
 		defer func() {

update_test.go

@@ -283,3 +283,95 @@ func TestUpdateBuilderClone(t *testing.T) {
 	clone.Asc().Limit(5)
 	a.NotEqual(ub.String(), clone.String())
 }
+
+func TestUpdateBuilderFrom(t *testing.T) {
+	a := assert.New(t)
+	ub := NewUpdateBuilder()
+	ub.Update("user")
+	ub.Set(ub.Assign("name", "Huan Du"))
+	ub.From("person")
+	ub.Where(ub.Equal("id", 123))
+
+	sql, _ := ub.BuildWithFlavor(MySQL)
+	a.Equal("UPDATE user SET name = ? WHERE id = ?", sql)
+
+	sql, _ = ub.BuildWithFlavor(PostgreSQL)
+	a.Equal("UPDATE user SET name = $1 FROM person WHERE id = $2", sql)
+
+	sql, _ = ub.BuildWithFlavor(SQLite)
+	a.Equal("UPDATE user SET name = ? FROM person WHERE id = ?", sql)
+
+	sql, _ = ub.BuildWithFlavor(SQLServer)
+	a.Equal("UPDATE user SET name = @p1 FROM person WHERE id = @p2", sql)
+
+	sql, _ = ub.BuildWithFlavor(CQL)
+	a.Equal("UPDATE user SET name = ? WHERE id = ?", sql)
+
+	sql, _ = ub.BuildWithFlavor(ClickHouse)
+	a.Equal("UPDATE user SET name = ? WHERE id = ?", sql)
+
+	sql, _ = ub.BuildWithFlavor(Presto)
+	a.Equal("UPDATE user SET name = ? WHERE id = ?", sql)
+
+	// Test with no from
+	ub2 := NewUpdateBuilder()
+	ub2.Update("user")
+	ub2.Set(ub2.Assign("name", "Test"))
+	ub2.From()
+	ub2.Where(ub2.Equal("id", 1))
+
+	sql, _ = ub2.BuildWithFlavor(PostgreSQL)
+	a.Equal("UPDATE user SET name = $1 WHERE id = $2", sql)
+
+	// Test with multiple from tables
+	ub3 := NewUpdateBuilder()
+	ub3.Update("user")
+	ub3.Set(ub3.Assign("name", "Test"))
+	ub3.From("person", "company")
+	ub3.Where(ub3.Equal("id", 1))
+
+	sql, _ = ub3.BuildWithFlavor(PostgreSQL)
+	a.Equal("UPDATE user SET name = $1 FROM person, company WHERE id = $2", sql)
+
+	// Test chaining
+	ub5 := NewUpdateBuilder().Update("user").Set("status = 1").From("person").From("company")
+	sql, _ = ub5.BuildWithFlavor(PostgreSQL)
+	a.Equal("UPDATE user SET status = 1 FROM company", sql) // Last From call overwrites
+
+	// Test SQL injection after FROM
+	ub6 := NewUpdateBuilder()
+	ub6.Update("user")
+	ub6.Set(ub6.Assign("name", "Test"))
+	ub6.From("person")
+	ub6.SQL("/* comment after from */")
+	ub6.Where(ub6.Equal("id", 1))
+
+	sql, _ = ub6.BuildWithFlavor(PostgreSQL)
+	a.Equal("UPDATE user SET name = $1 FROM person /* comment after from */ WHERE id = $2", sql)
+
+	// Test with CTE (WITH clause)
+	cte := With(CTETable("temp_user").As(Select("id").From("active_users")))
+	ub7 := cte.Update("user")
+	ub7.Set(ub7.Assign("status", "active"))
+	ub7.From("person")
+	ub7.Where("user.id IN (SELECT id FROM temp_user)")
+
+	sql, _ = ub7.BuildWithFlavor(PostgreSQL)
+	a.Equal("WITH temp_user AS (SELECT id FROM active_users) UPDATE user SET status = $1 FROM temp_user, person WHERE user.id IN (SELECT id FROM temp_user)", sql)
+
+	// Test with SQLServer Returning
+	ub8 := ub.Clone().Returning("id", "name")
+	sql, _ = ub8.BuildWithFlavor(SQLServer)
+	a.Equal("UPDATE user SET name = @p1 OUTPUT INSERTED.id, INSERTED.name FROM person WHERE id = @p2", sql)
+
+	// Test with SQL injection after WHERE
+	ub9 := NewUpdateBuilder()
+	ub9.Update("user")
+	ub9.Set(ub9.Assign("name", "Test"))
+	ub9.From("person")
+	ub9.Where("user.id = person.id")
+	ub9.SQL("/* comment after where */")
+
+	sql, _ = ub9.BuildWithFlavor(PostgreSQL)
+	a.Equal("UPDATE user SET name = $1 FROM person WHERE user.id = person.id /* comment after where */", sql)
+}