Merge pull request #179 from huandu/feature/cte-table-for-update-delete

Automatically ref names of CTETables in DELETE and UPDATE statements

Author: huandu

cte.go

@@ -138,12 +138,12 @@ func (cteb *CTEBuilder) TableNames() []string {
 	return tableNames
 }
 
-// tableNamesForSelect returns a list of table names which should be automatically added to FROM clause.
-// It's not public, as this feature is designed only for SelectBuilder right now.
-func (cteb *CTEBuilder) tableNamesForSelect() []string {
+// tableNamesForFrom returns a list of table names which should be automatically added to FROM clause.
+// It's not public, as this feature is designed only for SelectBuilder/UpdateBuilder/DeleteBuilder right now.
+func (cteb *CTEBuilder) tableNamesForFrom() []string {
 	cnt := 0
 
-	// It's rare that the ShouldAddToTableList() returns true.
+	// ShouldAddToTableList() unlikely returns true.
 	// Count it before allocating any memory for better performance.
 	for _, query := range cteb.queries {
 		if query.ShouldAddToTableList() {

cte_test.go

@@ -82,6 +82,43 @@ func ExampleCTEBuilder() {
 	// [users valid_users]
 }
 
+func ExampleCTEBuilder_update() {
+	builder := With(
+		CTETable("users", "user_id").As(
+			Select("user_id").From("vip_users"),
+		),
+	).Update("orders").Set(
+		"orders.transport_fee = 0",
+	).Where(
+		"users.user_id = orders.user_id",
+	)
+
+	sqlForMySQL, _ := builder.BuildWithFlavor(MySQL)
+	sqlForPostgreSQL, _ := builder.BuildWithFlavor(PostgreSQL)
+
+	fmt.Println(sqlForMySQL)
+	fmt.Println(sqlForPostgreSQL)
+
+	// Output:
+	// WITH users (user_id) AS (SELECT user_id FROM vip_users) UPDATE orders, users SET orders.transport_fee = 0 WHERE users.user_id = orders.user_id
+	// WITH users (user_id) AS (SELECT user_id FROM vip_users) UPDATE orders FROM users SET orders.transport_fee = 0 WHERE users.user_id = orders.user_id
+}
+
+func ExampleCTEBuilder_delete() {
+	sql := With(
+		CTETable("users", "user_id").As(
+			Select("user_id").From("cheaters"),
+		),
+	).DeleteFrom("awards").Where(
+		"users.user_id = awards.user_id",
+	).String()
+
+	fmt.Println(sql)
+
+	// Output:
+	// WITH users (user_id) AS (SELECT user_id FROM cheaters) DELETE FROM awards, users WHERE users.user_id = awards.user_id
+}
+
 func TestCTEBuilder(t *testing.T) {
 	a := assert.New(t)
 	cteb := newCTEBuilder()

delete.go

@@ -45,8 +45,10 @@ type DeleteBuilder struct {
 	whereClauseProxy *whereClauseProxy
 	whereClauseExpr  string
 
-	cteBuilder  string
-	table       string
+	cteBuilderVar string
+	cteBuilder    *CTEBuilder
+
+	tables      []string
 	orderByCols []string
 	order       string
 	limit       int
@@ -60,24 +62,48 @@ type DeleteBuilder struct {
 var _ Builder = new(DeleteBuilder)
 
 // DeleteFrom sets table name in DELETE.
-func DeleteFrom(table string) *DeleteBuilder {
-	return DefaultFlavor.NewDeleteBuilder().DeleteFrom(table)
+func DeleteFrom(table ...string) *DeleteBuilder {
+	return DefaultFlavor.NewDeleteBuilder().DeleteFrom(table...)
 }
 
 // With sets WITH clause (the Common Table Expression) before DELETE.
 func (db *DeleteBuilder) With(builder *CTEBuilder) *DeleteBuilder {
 	db.marker = deleteMarkerAfterWith
-	db.cteBuilder = db.Var(builder)
+	db.cteBuilderVar = db.Var(builder)
+	db.cteBuilder = builder
 	return db
 }
 
 // DeleteFrom sets table name in DELETE.
-func (db *DeleteBuilder) DeleteFrom(table string) *DeleteBuilder {
-	db.table = Escape(table)
+func (db *DeleteBuilder) DeleteFrom(table ...string) *DeleteBuilder {
+	db.tables = table
 	db.marker = deleteMarkerAfterDeleteFrom
 	return db
 }
 
+// TableNames returns all table names in this DELETE statement.
+func (db *DeleteBuilder) TableNames() []string {
+	var additionalTableNames []string
+
+	if db.cteBuilder != nil {
+		additionalTableNames = db.cteBuilder.tableNamesForFrom()
+	}
+
+	var tableNames []string
+
+	if len(db.tables) > 0 && len(additionalTableNames) > 0 {
+		tableNames = make([]string, len(db.tables)+len(additionalTableNames))
+		copy(tableNames, db.tables)
+		copy(tableNames[len(db.tables):], additionalTableNames)
+	} else if len(db.tables) > 0 {
+		tableNames = db.tables
+	} else if len(additionalTableNames) > 0 {
+		tableNames = additionalTableNames
+	}
+
+	return tableNames
+}
+
 // Where sets expressions of WHERE in DELETE.
 func (db *DeleteBuilder) Where(andExpr ...string) *DeleteBuilder {
 	if len(andExpr) == 0 || estimateStringsBytes(andExpr) == 0 {
@@ -146,17 +172,20 @@ func (db *DeleteBuilder) Build() (sql string, args []interface{}) {
 // BuildWithFlavor returns compiled DELETE string and args with flavor and initial args.
 // They can be used in `DB#Query` of package `database/sql` directly.
 func (db *DeleteBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{}) (sql string, args []interface{}) {
+
 	buf := newStringBuilder()
 	db.injection.WriteTo(buf, deleteMarkerInit)
 
-	if db.cteBuilder != "" {
-		buf.WriteLeadingString(db.cteBuilder)
+	if db.cteBuilder != nil {
+		buf.WriteLeadingString(db.cteBuilderVar)
 		db.injection.WriteTo(buf, deleteMarkerAfterWith)
 	}
 
-	if len(db.table) > 0 {
+	tableNames := db.TableNames()
+
+	if len(tableNames) > 0 {
 		buf.WriteLeadingString("DELETE FROM ")
-		buf.WriteString(db.table)
+		buf.WriteStrings(tableNames, ", ")
 	}
 
 	db.injection.WriteTo(buf, deleteMarkerAfterDeleteFrom)

select.go

@@ -96,12 +96,12 @@ func Select(col ...string) *SelectBuilder {
 	return DefaultFlavor.NewSelectBuilder().Select(col...)
 }
 
-// TableNames returns all table names in a SELECT.
+// TableNames returns all table names in this SELECT statement.
 func (sb *SelectBuilder) TableNames() []string {
 	var additionalTableNames []string
 
 	if sb.cteBuilder != nil {
-		additionalTableNames = sb.cteBuilder.tableNamesForSelect()
+		additionalTableNames = sb.cteBuilder.tableNamesForFrom()
 	}
 
 	var tableNames []string

update.go

@@ -47,8 +47,10 @@ type UpdateBuilder struct {
 	whereClauseProxy *whereClauseProxy
 	whereClauseExpr  string
 
-	cteBuilder  string
-	table       string
+	cteBuilderVar string
+	cteBuilder    *CTEBuilder
+
+	tables      []string
 	assignments []string
 	orderByCols []string
 	order       string
@@ -63,24 +65,46 @@ type UpdateBuilder struct {
 var _ Builder = new(UpdateBuilder)
 
 // Update sets table name in UPDATE.
-func Update(table string) *UpdateBuilder {
-	return DefaultFlavor.NewUpdateBuilder().Update(table)
+func Update(table ...string) *UpdateBuilder {
+	return DefaultFlavor.NewUpdateBuilder().Update(table...)
 }
 
 // With sets WITH clause (the Common Table Expression) before UPDATE.
 func (ub *UpdateBuilder) With(builder *CTEBuilder) *UpdateBuilder {
 	ub.marker = updateMarkerAfterWith
-	ub.cteBuilder = ub.Var(builder)
+	ub.cteBuilderVar = ub.Var(builder)
+	ub.cteBuilder = builder
 	return ub
 }
 
 // Update sets table name in UPDATE.
-func (ub *UpdateBuilder) Update(table string) *UpdateBuilder {
-	ub.table = Escape(table)
+func (ub *UpdateBuilder) Update(table ...string) *UpdateBuilder {
+	ub.tables = table
 	ub.marker = updateMarkerAfterUpdate
 	return ub
 }
 
+// TableNames returns all table names in this UPDATE statement.
+func (ub *UpdateBuilder) TableNames() (tableNames []string) {
+	var additionalTableNames []string
+
+	if ub.cteBuilder != nil {
+		additionalTableNames = ub.cteBuilder.tableNamesForFrom()
+	}
+
+	if len(ub.tables) > 0 && len(additionalTableNames) > 0 {
+		tableNames = make([]string, len(ub.tables)+len(additionalTableNames))
+		copy(tableNames, ub.tables)
+		copy(tableNames[len(ub.tables):], additionalTableNames)
+	} else if len(ub.tables) > 0 {
+		tableNames = ub.tables
+	} else if len(additionalTableNames) > 0 {
+		tableNames = additionalTableNames
+	}
+
+	return tableNames
+}
+
 // Set sets the assignments in SET.
 func (ub *UpdateBuilder) Set(assignment ...string) *UpdateBuilder {
 	ub.assignments = assignment
@@ -212,14 +236,36 @@ func (ub *UpdateBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 	buf := newStringBuilder()
 	ub.injection.WriteTo(buf, updateMarkerInit)
 
-	if ub.cteBuilder != "" {
-		buf.WriteLeadingString(ub.cteBuilder)
+	if ub.cteBuilder != nil {
+		buf.WriteLeadingString(ub.cteBuilderVar)
 		ub.injection.WriteTo(buf, updateMarkerAfterWith)
 	}
 
-	if len(ub.table) > 0 {
-		buf.WriteLeadingString("UPDATE ")
-		buf.WriteString(ub.table)
+	switch flavor {
+	case MySQL:
+		// CTE table names should be written after UPDATE keyword in MySQL.
+		tableNames := ub.TableNames()
+
+		if len(tableNames) > 0 {
+			buf.WriteLeadingString("UPDATE ")
+			buf.WriteStrings(tableNames, ", ")
+		}
+
+	default:
+		if len(ub.tables) > 0 {
+			buf.WriteLeadingString("UPDATE ")
+			buf.WriteStrings(ub.tables, ", ")
+
+			// For ISO SQL, CTE table names should be written after FROM keyword.
+			if ub.cteBuilder != nil {
+				cteTableNames := ub.cteBuilder.tableNamesForFrom()
+
+				if len(cteTableNames) > 0 {
+					buf.WriteLeadingString("FROM ")
+					buf.WriteStrings(cteTableNames, ", ")
+				}
+			}
+		}
 	}
 
 	ub.injection.WriteTo(buf, updateMarkerAfterUpdate)