Lightweight and fast SQL builder for Go language
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// Copyright 2016 The Xorm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package builder
import (
"fmt"
)
// Select creates a select Builder
func Select(cols ...string) *Builder {
builder := &Builder{cond: NewCond()}
return builder.Select(cols...)
}
func (b *Builder) selectWriteTo(w Writer) error {
if len(b.from) <= 0 && !b.isNested {
return ErrNoTableName
}
// perform limit before writing to writer when b.dialect between ORACLE and MSSQL
// this avoid a duplicate writing problem in simple limit query
if b.limitation != nil && (b.dialect == ORACLE || b.dialect == MSSQL) {
return b.limitWriteTo(w)
}
if _, err := fmt.Fprint(w, "SELECT "); err != nil {
return err
}
if len(b.selects) > 0 {
for i, s := range b.selects {
if _, err := fmt.Fprint(w, s); err != nil {
return err
}
if i != len(b.selects)-1 {
if _, err := fmt.Fprint(w, ","); err != nil {
return err
}
}
}
} else {
if _, err := fmt.Fprint(w, "*"); err != nil {
return err
}
}
if b.subQuery == nil {
if _, err := fmt.Fprint(w, " FROM ", b.from); err != nil {
return err
}
} else {
if b.cond.IsValid() && len(b.from) <= 0 {
return ErrUnnamedDerivedTable
}
if b.subQuery.dialect != "" && b.dialect != b.subQuery.dialect {
return ErrInconsistentDialect
}
// dialect of sub-query will inherit from the main one (if not set up)
if b.dialect != "" && b.subQuery.dialect == "" {
b.subQuery.dialect = b.dialect
}
switch b.subQuery.optype {
case selectType, setOpType:
fmt.Fprint(w, " FROM (")
if err := b.subQuery.WriteTo(w); err != nil {
return err
}
if len(b.from) == 0 {
fmt.Fprintf(w, ")")
} else {
fmt.Fprintf(w, ") %v", b.from)
}
default:
return ErrUnexpectedSubQuery
}
}
for _, v := range b.joins {
b, ok := v.joinTable.(*Builder)
if ok {
if _, err := fmt.Fprintf(w, " %s JOIN (", v.joinType); err != nil {
return err
}
if err := b.WriteTo(w); err != nil {
return err
}
if _, err := fmt.Fprintf(w, ") ON "); err != nil {
return err
}
} else {
if _, err := fmt.Fprintf(w, " %s JOIN %s ON ", v.joinType, v.joinTable); err != nil {
return err
}
}
if err := v.joinCond.WriteTo(w); err != nil {
return err
}
}
if b.cond.IsValid() {
if _, err := fmt.Fprint(w, " WHERE "); err != nil {
return err
}
if err := b.cond.WriteTo(w); err != nil {
return err
}
}
if len(b.groupBy) > 0 {
if _, err := fmt.Fprint(w, " GROUP BY ", b.groupBy); err != nil {
return err
}
}
if len(b.having) > 0 {
if _, err := fmt.Fprint(w, " HAVING ", b.having); err != nil {
return err
}
}
if len(b.orderBy) > 0 {
if _, err := fmt.Fprint(w, " ORDER BY ", b.orderBy); err != nil {
return err
}
}
if b.limitation != nil {
if err := b.limitWriteTo(w); err != nil {
return err
}
}
return nil
}
// OrderBy orderBy SQL
func (b *Builder) OrderBy(orderBy string) *Builder {
b.orderBy = orderBy
return b
}
// GroupBy groupby SQL
func (b *Builder) GroupBy(groupby string) *Builder {
b.groupBy = groupby
return b
}
// Having having SQL
func (b *Builder) Having(having string) *Builder {
b.having = having
return b
}