104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
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// Copyright 2018 The Xorm Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package builder
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import (
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"fmt"
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"strings"
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)
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func (b *Builder) limitWriteTo(w Writer) error {
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if strings.TrimSpace(b.dialect) == "" {
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return ErrDialectNotSetUp
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}
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if b.limitation != nil {
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limit := b.limitation
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if limit.offset < 0 || limit.limitN <= 0 {
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return ErrInvalidLimitation
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}
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// erase limit condition
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b.limitation = nil
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defer func() {
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b.limitation = limit
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}()
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ow := w.(*BytesWriter)
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switch strings.ToLower(strings.TrimSpace(b.dialect)) {
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case ORACLE:
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if len(b.selects) == 0 {
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b.selects = append(b.selects, "*")
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}
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var final *Builder
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selects := b.selects
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b.selects = append(selects, "ROWNUM RN")
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var wb *Builder
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if b.optype == setOpType {
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wb = Dialect(b.dialect).Select("at.*", "ROWNUM RN").
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From(b, "at")
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} else {
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wb = b
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}
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if limit.offset == 0 {
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final = Dialect(b.dialect).Select(selects...).From(wb, "at").
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Where(Lte{"at.RN": limit.limitN})
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} else {
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sub := Dialect(b.dialect).Select("*").
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From(b, "at").Where(Lte{"at.RN": limit.offset + limit.limitN})
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final = Dialect(b.dialect).Select(selects...).From(sub, "att").
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Where(Gt{"att.RN": limit.offset})
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}
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return final.WriteTo(ow)
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case SQLITE, MYSQL, POSTGRES:
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// if type UNION, we need to write previous content back to current writer
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if b.optype == setOpType {
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if err := b.WriteTo(ow); err != nil {
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return err
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}
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}
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if limit.offset == 0 {
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fmt.Fprint(ow, " LIMIT ", limit.limitN)
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} else {
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fmt.Fprintf(ow, " LIMIT %v OFFSET %v", limit.limitN, limit.offset)
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}
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case MSSQL:
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if len(b.selects) == 0 {
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b.selects = append(b.selects, "*")
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}
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var final *Builder
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selects := b.selects
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b.selects = append(append([]string{fmt.Sprintf("TOP %d %v", limit.limitN+limit.offset, b.selects[0])},
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b.selects[1:]...), "ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS RN")
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var wb *Builder
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if b.optype == setOpType {
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wb = Dialect(b.dialect).Select("*", "ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS RN").
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From(b, "at")
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} else {
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wb = b
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}
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if limit.offset == 0 {
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final = Dialect(b.dialect).Select(selects...).From(wb, "at")
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} else {
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final = Dialect(b.dialect).Select(selects...).From(wb, "at").Where(Gt{"at.RN": limit.offset})
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}
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return final.WriteTo(ow)
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default:
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return ErrNotSupportType
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}
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}
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return nil
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}
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