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Merge pull request #216 from zhangyongding/union-support-limit

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fix: union limit
This commit is contained in:
Huan Du
2025-09-17 13:48:52 +08:00
committed by GitHub
parent e47fcc5fb9 fb0b217e0f
commit 88a656d237
2 changed files with 261 additions and 7 deletions
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union.go
+118 -5
View File
@@ -3,6 +3,10 @@
package sqlbuilder
import (
"fmt"
)
const (
unionDistinct = " UNION " // Default union type is DISTINCT.
unionAll = " UNION ALL "
@@ -140,9 +144,16 @@ func (ub *UnionBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{}
buf := newStringBuilder()
ub.injection.WriteTo(buf, unionMarkerInit)
nestedSelect := (flavor == Oracle && (len(ub.limitVar) > 0 || len(ub.offsetVar) > 0)) ||
(flavor == Informix && len(ub.limitVar) > 0)
if len(ub.builderVars) > 0 {
needParen := flavor != SQLite
if nestedSelect {
buf.WriteLeadingString("SELECT * FROM (")
}
if needParen {
buf.WriteLeadingString("(")
buf.WriteString(ub.builderVars[0])
@@ -164,6 +175,10 @@ func (ub *UnionBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{}
buf.WriteRune(')')
}
}
if nestedSelect {
buf.WriteLeadingString(")")
}
}
ub.injection.WriteTo(buf, unionMarkerAfterUnion)
@@ -180,17 +195,115 @@ func (ub *UnionBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{}
ub.injection.WriteTo(buf, unionMarkerAfterOrderBy)
}
if len(ub.limitVar) > 0 {
buf.WriteLeadingString("LIMIT ")
buf.WriteString(ub.limitVar)
switch flavor {
case MySQL, SQLite, ClickHouse:
if len(ub.limitVar) > 0 {
buf.WriteLeadingString("LIMIT ")
buf.WriteString(ub.limitVar)
}
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("OFFSET ")
buf.WriteString(ub.offsetVar)
}
}
case CQL:
if len(ub.limitVar) > 0 {
buf.WriteLeadingString("LIMIT ")
buf.WriteString(ub.limitVar)
}
case PostgreSQL:
if len(ub.limitVar) > 0 {
buf.WriteLeadingString("LIMIT ")
buf.WriteString(ub.limitVar)
}
if ((MySQL == flavor || Informix == flavor) && len(ub.limitVar) > 0) || PostgreSQL == flavor {
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("OFFSET ")
buf.WriteString(ub.offsetVar)
}
case Presto:
// There might be a hidden constraint in Presto requiring offset to be set before limit.
// The select statement documentation (https://prestodb.io/docs/current/sql/select.html)
// puts offset before limit, and Trino, which is based on Presto, seems
// to require this specific order.
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("OFFSET ")
buf.WriteString(ub.offsetVar)
}
if len(ub.limitVar) > 0 {
buf.WriteLeadingString("LIMIT ")
buf.WriteString(ub.limitVar)
}
case SQLServer:
// If ORDER BY is not set, sort column #1 by default.
// It's required to make OFFSET...FETCH work.
if len(ub.orderByCols) == 0 && (len(ub.limitVar) > 0 || len(ub.offsetVar) > 0) {
buf.WriteLeadingString("ORDER BY 1")
}
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("OFFSET ")
buf.WriteString(ub.offsetVar)
buf.WriteString(" ROWS")
}
if len(ub.limitVar) > 0 {
if len(ub.offsetVar) == 0 {
buf.WriteLeadingString("OFFSET 0 ROWS")
}
buf.WriteLeadingString("FETCH NEXT ")
buf.WriteString(ub.limitVar)
buf.WriteString(" ROWS ONLY")
}
case Oracle:
// It's required to make OFFSET...FETCH work.
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("OFFSET ")
buf.WriteString(ub.offsetVar)
buf.WriteString(" ROWS")
}
if len(ub.limitVar) > 0 {
if len(ub.offsetVar) == 0 {
buf.WriteLeadingString("OFFSET 0 ROWS")
}
buf.WriteLeadingString("FETCH NEXT ")
buf.WriteString(ub.limitVar)
buf.WriteString(" ROWS ONLY")
}
case Informix:
// [SKIP N] FIRST M
// M must be greater than 0
if len(ub.limitVar) > 0 {
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("SKIP ")
buf.WriteString(ub.offsetVar)
}
buf.WriteLeadingString("FIRST ")
buf.WriteString(ub.limitVar)
}
case Doris:
// #192: Doris doesn't support ? in OFFSET and LIMIT.
if len(ub.limitVar) > 0 {
buf.WriteLeadingString("LIMIT ")
buf.WriteString(fmt.Sprint(ub.args.Value(ub.limitVar)))
if len(ub.offsetVar) > 0 {
buf.WriteLeadingString("OFFSET ")
buf.WriteString(fmt.Sprint(ub.args.Value(ub.offsetVar)))
}
}
}
if len(ub.limitVar) > 0 {
union_test.go
+143 -2
View File
@@ -87,9 +87,9 @@ func TestUnionForSQLite(t *testing.T) {
a := assert.New(t)
sb1 := Select("id", "name").From("users").Where("created_at > DATE('now', '-15 days')")
sb2 := Select("id", "nick_name").From("user_extras").Where("status IN (1, 2, 3)")
sql, _ := UnionAll(sb1, sb2).OrderBy("id").BuildWithFlavor(SQLite)
sql, _ := UnionAll(sb1, sb2).OrderBy("id").Limit(100).Offset(5).BuildWithFlavor(SQLite)
a.Equal(sql, "SELECT id, name FROM users WHERE created_at > DATE('now', '-15 days') UNION ALL SELECT id, nick_name FROM user_extras WHERE status IN (1, 2, 3) ORDER BY id")
a.Equal(sql, "SELECT id, name FROM users WHERE created_at > DATE('now', '-15 days') UNION ALL SELECT id, nick_name FROM user_extras WHERE status IN (1, 2, 3) ORDER BY id LIMIT ? OFFSET ?")
}
func TestUnionBuilderGetFlavor(t *testing.T) {
@@ -104,3 +104,144 @@ func TestUnionBuilderGetFlavor(t *testing.T) {
flavor = ubClick.Flavor()
a.Equal(ClickHouse, flavor)
}
func ExampleUnionBuilder_limit_offset() {
flavors := []Flavor{MySQL, PostgreSQL, SQLite, SQLServer, CQL, ClickHouse, Presto, Oracle, Informix, Doris}
results := make([][]string, len(flavors))
ub := NewUnionBuilder()
saveResults := func() {
sb1 := NewSelectBuilder()
sb1.Select("*").From("user1")
sb2 := NewSelectBuilder()
sb2.Select("*").From("user2")
ub.Union(sb1, sb2)
for i, f := range flavors {
s, _ := ub.BuildWithFlavor(f)
results[i] = append(results[i], s)
}
}
// Case #1: limit < 0 and offset < 0
//
// All: No limit or offset in query.
ub.Limit(-1)
ub.Offset(-1)
saveResults()
// Case #2: limit < 0 and offset >= 0
//
// MySQL and SQLite: Ignore offset if the limit is not set.
// PostgreSQL: Offset can be set without limit.
// SQLServer: Offset can be set without limit.
// CQL: Ignore offset.
// Oracle: Offset can be set without limit.
ub.Limit(-1)
ub.Offset(0)
saveResults()
// Case #3: limit >= 0 and offset >= 0
//
// CQL: Ignore offset.
// All others: Set both limit and offset.
ub.Limit(1)
ub.Offset(0)
saveResults()
// Case #4: limit >= 0 and offset < 0
//
// All: Set limit in query.
ub.Limit(1)
ub.Offset(-1)
saveResults()
// Case #5: limit >= 0 and offset >= 0 order by id
//
// CQL: Ignore offset.
// All others: Set both limit and offset.
ub.Limit(1)
ub.Offset(1)
ub.OrderBy("id")
saveResults()
for i, result := range results {
fmt.Println()
fmt.Println(flavors[i])
for n, s := range result {
fmt.Printf("#%d: %s\n", n+1, s)
}
}
// Output:
//
// MySQL
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ? OFFSET ?
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ?
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id LIMIT ? OFFSET ?
//
// PostgreSQL
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2) OFFSET $1
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT $1 OFFSET $2
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT $1
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id LIMIT $1 OFFSET $2
//
// SQLite
// #1: SELECT * FROM user1 UNION SELECT * FROM user2
// #2: SELECT * FROM user1 UNION SELECT * FROM user2
// #3: SELECT * FROM user1 UNION SELECT * FROM user2 LIMIT ? OFFSET ?
// #4: SELECT * FROM user1 UNION SELECT * FROM user2 LIMIT ?
// #5: SELECT * FROM user1 UNION SELECT * FROM user2 ORDER BY id LIMIT ? OFFSET ?
//
// SQLServer
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY 1 OFFSET @p1 ROWS
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY 1 OFFSET @p1 ROWS FETCH NEXT @p2 ROWS ONLY
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY 1 OFFSET 0 ROWS FETCH NEXT @p1 ROWS ONLY
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id OFFSET @p1 ROWS FETCH NEXT @p2 ROWS ONLY
//
// CQL
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ?
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ?
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id LIMIT ?
//
// ClickHouse
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ? OFFSET ?
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ?
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id LIMIT ? OFFSET ?
//
// Presto
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2) OFFSET ?
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) OFFSET ? LIMIT ?
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT ?
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id OFFSET ? LIMIT ?
//
// Oracle
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) OFFSET :1 ROWS
// #3: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) OFFSET :1 ROWS FETCH NEXT :2 ROWS ONLY
// #4: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) OFFSET 0 ROWS FETCH NEXT :1 ROWS ONLY
// #5: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) ORDER BY id OFFSET :1 ROWS FETCH NEXT :2 ROWS ONLY
//
// Informix
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #3: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) SKIP ? FIRST ?
// #4: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) FIRST ?
// #5: SELECT * FROM ( (SELECT * FROM user1) UNION (SELECT * FROM user2) ) ORDER BY id SKIP ? FIRST ?
//
// Doris
// #1: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #2: (SELECT * FROM user1) UNION (SELECT * FROM user2)
// #3: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT 1 OFFSET 0
// #4: (SELECT * FROM user1) UNION (SELECT * FROM user2) LIMIT 1
// #5: (SELECT * FROM user1) UNION (SELECT * FROM user2) ORDER BY id LIMIT 1 OFFSET 1
}