Types through CTEs, window functions and views: MariaDB and SQLite
Every file of the MariaDB and SQLite versions side by side, with the lines that differ marked. 4 parameter or column types differ in Go.
Configuration
sgl.yamldiffers
MariaDB
SQLite
1
version: 11
version: 12
2
3
databases:3
databases:4
- name: colony4
- name: colony5
dialect: mysql5
dialect: sqlite6
migrations: db/migrations6
migrations: db/migrations7
queries: db/queries7
queries: db/queries8
go:8
go:9
package: store9
package: store10
out: internal/store10
out: internal/storeMigrations
db/migrations/0001_gulls.up.sqldiffers
MariaDB
SQLite
1
CREATE TABLE gulls (1
CREATE TABLE gulls (2
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,2
id INTEGER PRIMARY KEY,3
name VARCHAR(50) NOT NULL,3
name TEXT NOT NULL,4
parent_id BIGINT,4
parent_id INTEGER REFERENCES gulls (id),5
beach VARCHAR(50) NOT NULL,5
beach TEXT NOT NULL6
FOREIGN KEY (parent_id) REFERENCES gulls (id)7
);6
);8
7
9
CREATE TABLE thefts (8
CREATE TABLE thefts (10
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,9
id INTEGER PRIMARY KEY,11
gull_id BIGINT NOT NULL,10
gull_id INTEGER NOT NULL REFERENCES gulls (id),12
snack VARCHAR(50) NOT NULL,11
snack TEXT NOT NULL,13
stolen_on DATE NOT NULL,12
stolen_on TEXT NOT NULL14
FOREIGN KEY (gull_id) REFERENCES gulls (id)15
);13
);16
14
17
CREATE VIEW beach_records AS15
CREATE VIEW beach_records AS18
SELECT16
SELECT19
gulls.beach,17
gulls.beach,20
COUNT(DISTINCT gulls.id) AS gulls,18
COUNT(DISTINCT gulls.id) AS gulls,21
COUNT(thefts.id) AS thefts,19
COUNT(thefts.id) AS thefts,22
MAX(thefts.stolen_on) AS last_theft20
MAX(thefts.stolen_on) AS last_theft23
FROM gulls21
FROM gulls24
LEFT JOIN thefts ON thefts.gull_id = gulls.id22
LEFT JOIN thefts ON thefts.gull_id = gulls.id25
GROUP BY gulls.beach;23
GROUP BY gulls.beach;db/migrations/0001_gulls.down.sqlidentical
MariaDB
SQLite
1
DROP VIEW beach_records;1
DROP VIEW beach_records;2
DROP TABLE thefts;2
DROP TABLE thefts;3
DROP TABLE gulls;3
DROP TABLE gulls;Queries
HatchGullidentical
MariaDB · db/queries/gulls.sql
SQLite · db/queries/gulls.sql
1
-- sgl.query(HatchGull, exec)1
-- sgl.query(HatchGull, exec)2
INSERT INTO gulls (name, parent_id, beach) VALUES (?, ?, ?);2
INSERT INTO gulls (name, parent_id, beach) VALUES (?, ?, ?);RecordTheftidentical
MariaDB · db/queries/gulls.sql
SQLite · db/queries/gulls.sql
1
-- sgl.query(RecordTheft, exec)1
-- sgl.query(RecordTheft, exec)2
INSERT INTO thefts (gull_id, snack, stolen_on) VALUES (?, ?, ?);2
INSERT INTO thefts (gull_id, snack, stolen_on) VALUES (?, ?, ?);FamilyTreeidentical
MariaDB · db/queries/gulls.sql
SQLite · db/queries/gulls.sql
1
-- sgl.query(FamilyTree, many)1
-- sgl.query(FamilyTree, many)2
WITH RECURSIVE family AS (2
WITH RECURSIVE family AS (3
SELECT id, name, parent_id, 0 AS generation3
SELECT id, name, parent_id, 0 AS generation4
FROM gulls4
FROM gulls5
WHERE id = ?5
WHERE id = ?6
UNION ALL6
UNION ALL7
SELECT gulls.id, gulls.name, gulls.parent_id, family.generation + 17
SELECT gulls.id, gulls.name, gulls.parent_id, family.generation + 18
FROM gulls8
FROM gulls9
JOIN family ON gulls.parent_id = family.id9
JOIN family ON gulls.parent_id = family.id10
)10
)11
SELECT family.name, family.generation, parents.name AS parent11
SELECT family.name, family.generation, parents.name AS parent12
FROM family12
FROM family13
LEFT JOIN gulls AS parents ON parents.id = family.parent_id13
LEFT JOIN gulls AS parents ON parents.id = family.parent_id14
ORDER BY family.generation, family.id;14
ORDER BY family.generation, family.id;TheftLeagueidentical
MariaDB · db/queries/gulls.sql
SQLite · db/queries/gulls.sql
1
-- sgl.query(TheftLeague, many)1
-- sgl.query(TheftLeague, many)2
WITH totals AS (2
WITH totals AS (3
SELECT gulls.name, gulls.beach, COUNT(thefts.id) AS thefts3
SELECT gulls.name, gulls.beach, COUNT(thefts.id) AS thefts4
FROM gulls4
FROM gulls5
LEFT JOIN thefts ON thefts.gull_id = gulls.id5
LEFT JOIN thefts ON thefts.gull_id = gulls.id6
GROUP BY gulls.id6
GROUP BY gulls.id7
)7
)8
SELECT8
SELECT9
name,9
name,10
beach,10
beach,11
thefts,11
thefts,12
RANK() OVER (PARTITION BY beach ORDER BY thefts DESC) AS beach_rank,12
RANK() OVER (PARTITION BY beach ORDER BY thefts DESC) AS beach_rank,13
SUM(thefts) OVER (PARTITION BY beach) AS beach_thefts13
SUM(thefts) OVER (PARTITION BY beach) AS beach_thefts14
FROM totals14
FROM totals15
ORDER BY beach, beach_rank, name;15
ORDER BY beach, beach_rank, name;BeachRecordsidentical
MariaDB · db/queries/gulls.sql
SQLite · db/queries/gulls.sql
1
-- sgl.query(BeachRecords, many)1
-- sgl.query(BeachRecords, many)2
SELECT beach, gulls, thefts, last_theft FROM beach_records ORDER BY beach;2
SELECT beach, gulls, thefts, last_theft FROM beach_records ORDER BY beach;What sgl generates
HatchGullidentical
MariaDB
SQLite
1
func (queries *Queries) HatchGull(ctx context.Context, params HatchGullParams) error1
func (queries *Queries) HatchGull(ctx context.Context, params HatchGullParams) error2
2
3
type HatchGullParams struct {3
type HatchGullParams struct {4
Name string4
Name string5
ParentID *int645
ParentID *int646
Beach string6
Beach string7
}7
}RecordTheftdiffers
MariaDB
SQLite
1
func (queries *Queries) RecordTheft(ctx context.Context, params RecordTheftParams) error1
func (queries *Queries) RecordTheft(ctx context.Context, params RecordTheftParams) error2
2
3
type RecordTheftParams struct {3
type RecordTheftParams struct {4
GullID int644
GullID int645
Snack string5
Snack string6
StolenOn time.Time6
StolenOn string7
}7
}FamilyTreediffers
MariaDB
SQLite
1
func (queries *Queries) FamilyTree(ctx context.Context, id int64) ([]FamilyTreeRow, error)1
func (queries *Queries) FamilyTree(ctx context.Context, id int64) ([]FamilyTreeRow, error)2
2
3
type FamilyTreeRow struct {3
type FamilyTreeRow struct {4
Name string `json:"name"`4
Name string `json:"name"`5
Generation int32 `json:"generation"`5
Generation int64 `json:"generation"`6
Parent *string `json:"parent"`6
Parent *string `json:"parent"`7
}7
}TheftLeaguediffers
MariaDB
SQLite
1
func (queries *Queries) TheftLeague(ctx context.Context) ([]TheftLeagueRow, error)1
func (queries *Queries) TheftLeague(ctx context.Context) ([]TheftLeagueRow, error)2
2
3
type TheftLeagueRow struct {3
type TheftLeagueRow struct {4
Name string `json:"name"`4
Name string `json:"name"`5
Beach string `json:"beach"`5
Beach string `json:"beach"`6
Thefts int64 `json:"thefts"`6
Thefts int64 `json:"thefts"`7
BeachRank int64 `json:"beach_rank"`7
BeachRank int64 `json:"beach_rank"`8
BeachThefts *apd.Decimal `json:"beach_thefts"`8
BeachThefts *int64 `json:"beach_thefts"`9
}9
}BeachRecordsdiffers
MariaDB
SQLite
1
func (queries *Queries) BeachRecords(ctx context.Context) ([]BeachRecordsRow, error)1
func (queries *Queries) BeachRecords(ctx context.Context) ([]BeachRecordsRow, error)2
2
3
type BeachRecordsRow struct {3
type BeachRecordsRow struct {4
Beach string `json:"beach"`4
Beach string `json:"beach"`5
Gulls int64 `json:"gulls"`5
Gulls int64 `json:"gulls"`6
Thefts int64 `json:"thefts"`6
Thefts int64 `json:"thefts"`7
LastTheft *time.Time `json:"last_theft"`7
LastTheft *string `json:"last_theft"`8
}8
}The program
example.godiffers
MariaDB
SQLite
1
package main1
package main2
2
3
import (3
import (4
"context"4
"context"5
"database/sql"5
"database/sql"6
"fmt"6
"fmt"7
"io"7
"io"8
"time"9
8
10
"seagull.sh/seagull/examples/mysql/019_ctes_and_windows/internal/store"9
"seagull.sh/seagull/examples/sqlite/019_ctes_and_windows/internal/store"11
)10
)12
11
13
// run hatches a colony of gulls, records their snack thefts and reads them back three12
// run hatches a colony of gulls, records their snack thefts and reads them back three14
// ways. Seagull follows each column's type and nullability through the SQL:13
// ways. Seagull follows each column's type and nullability through the SQL:15
//14
//16
// - FamilyTree's recursive CTE starts from one gull and joins its chicks generation by15
// - FamilyTree's recursive CTE starts from one gull and joins its chicks generation by17
// generation; generation is an integer from 0 AS generation and generation + 1, and16
// generation; generation is an integer from 0 AS generation and generation + 1, and18
// parent is *string because the LEFT JOIN finds no parent for the first gull;17
// parent is *string because the LEFT JOIN finds no parent for the first gull;19
// - TheftLeague counts thefts in a CTE, then ranks gulls on each beach with RANK() and18
// - TheftLeague counts thefts in a CTE, then ranks gulls on each beach with RANK() and20
// totals the beach with SUM() OVER; RANK is never NULL, while SUM is nullable, as SQL19
// totals the beach with SUM() OVER; RANK is never NULL, while SUM is nullable, as SQL21
// sums no rows to NULL, and it is a DECIMAL, as MySQL sums integers exactly into a20
// sums no rows to NULL;22
// DECIMAL, so BeachThefts is *apd.Decimal;23
// - BeachRecords reads the beach_records view from the migration as if it were a table,21
// - BeachRecords reads the beach_records view from the migration as if it were a table,24
// and its columns keep the types the view's own SELECT gives them.22
// and its columns keep the types the view's own SELECT gives them.25
//23
//26
// Takes database (*sql.DB) which is a migrated database.24
// Takes database (*sql.DB) which is a migrated database.27
// Takes output (io.Writer) which receives the three listings.25
// Takes output (io.Writer) which receives the three listings.28
//26
//29
// Returns error when a query fails.27
// Returns error when a query fails.30
func run(ctx context.Context, database *sql.DB, output io.Writer) error {28
func run(ctx context.Context, database *sql.DB, output io.Writer) error {31
queries := store.New(database)29
queries := store.New(database)32
30
33
gulls := []store.HatchGullParams{31
gulls := []store.HatchGullParams{34
{Name: "Steven", ParentID: nil, Beach: "Porthmeor"},32
{Name: "Steven", ParentID: nil, Beach: "Porthmeor"},35
{Name: "Gwen", ParentID: new(int64(1)), Beach: "Porthmeor"},33
{Name: "Gwen", ParentID: new(int64(1)), Beach: "Porthmeor"},36
{Name: "Jago", ParentID: new(int64(1)), Beach: "Porthminster"},34
{Name: "Jago", ParentID: new(int64(1)), Beach: "Porthminster"},37
{Name: "Kerensa", ParentID: new(int64(2)), Beach: "Porthmeor"},35
{Name: "Kerensa", ParentID: new(int64(2)), Beach: "Porthmeor"},38
{Name: "Tristan", ParentID: nil, Beach: "Porthminster"},36
{Name: "Tristan", ParentID: nil, Beach: "Porthminster"},39
{Name: "Morwenna", ParentID: nil, Beach: "Gwithian"},37
{Name: "Morwenna", ParentID: nil, Beach: "Gwithian"},40
}38
}41
for _, gull := range gulls {39
for _, gull := range gulls {42
if err := queries.HatchGull(ctx, gull); err != nil {40
if err := queries.HatchGull(ctx, gull); err != nil {43
return fmt.Errorf("hatching %s: %w", gull.Name, err)41
return fmt.Errorf("hatching %s: %w", gull.Name, err)44
}42
}45
}43
}46
thefts := []store.RecordTheftParams{44
thefts := []store.RecordTheftParams{47
{GullID: 1, Snack: "chips", StolenOn: day(1)},45
{GullID: 1, Snack: "chips", StolenOn: "2026-07-01"},48
{GullID: 1, Snack: "pasty", StolenOn: day(3)},46
{GullID: 1, Snack: "pasty", StolenOn: "2026-07-03"},49
{GullID: 1, Snack: "ice cream", StolenOn: day(4)},47
{GullID: 1, Snack: "ice cream", StolenOn: "2026-07-04"},50
{GullID: 2, Snack: "chips", StolenOn: day(2)},48
{GullID: 2, Snack: "chips", StolenOn: "2026-07-02"},51
{GullID: 3, Snack: "pasty", StolenOn: day(2)},49
{GullID: 3, Snack: "pasty", StolenOn: "2026-07-02"},52
{GullID: 3, Snack: "chips", StolenOn: day(5)},50
{GullID: 3, Snack: "chips", StolenOn: "2026-07-05"},53
{GullID: 5, Snack: "sandwich", StolenOn: day(3)},51
{GullID: 5, Snack: "sandwich", StolenOn: "2026-07-03"},54
}52
}55
for _, theft := range thefts {53
for _, theft := range thefts {56
if err := queries.RecordTheft(ctx, theft); err != nil {54
if err := queries.RecordTheft(ctx, theft); err != nil {57
return fmt.Errorf("recording a theft: %w", err)55
return fmt.Errorf("recording a theft: %w", err)58
}56
}59
}57
}60
58
61
family, err := queries.FamilyTree(ctx, 1)59
family, err := queries.FamilyTree(ctx, 1)62
if err != nil {60
if err != nil {63
return fmt.Errorf("tracing Steven's family: %w", err)61
return fmt.Errorf("tracing Steven's family: %w", err)64
}62
}65
fmt.Fprintln(output, "Steven's family:")63
fmt.Fprintln(output, "Steven's family:")66
for _, member := range family {64
for _, member := range family {67
fmt.Fprintf(output, " generation %d %-8s parent %s\n", member.Generation, member.Name, orNull(member.Parent))65
fmt.Fprintf(output, " generation %d %-8s parent %s\n", member.Generation, member.Name, orNull(member.Parent))68
}66
}69
67
70
league, err := queries.TheftLeague(ctx)68
league, err := queries.TheftLeague(ctx)71
if err != nil {69
if err != nil {72
return fmt.Errorf("ranking thieves: %w", err)70
return fmt.Errorf("ranking thieves: %w", err)73
}71
}74
fmt.Fprintln(output, "theft league:")72
fmt.Fprintln(output, "theft league:")75
for _, entry := range league {73
for _, entry := range league {76
fmt.Fprintf(output, " %-13s #%d %-8s %d of %s\n", entry.Beach, entry.BeachRank, entry.Name, entry.Thefts, orNull(entry.BeachThefts))74
fmt.Fprintf(output, " %-13s #%d %-8s %d of %s\n", entry.Beach, entry.BeachRank, entry.Name, entry.Thefts, orNull(entry.BeachThefts))77
}75
}78
76
79
records, err := queries.BeachRecords(ctx)77
records, err := queries.BeachRecords(ctx)80
if err != nil {78
if err != nil {81
return fmt.Errorf("reading beach records: %w", err)79
return fmt.Errorf("reading beach records: %w", err)82
}80
}83
fmt.Fprintln(output, "beach records:")81
fmt.Fprintln(output, "beach records:")84
for _, record := range records {82
for _, record := range records {85
fmt.Fprintf(output, " %-13s gulls %d, thefts %d, last theft %s\n", record.Beach, record.Gulls, record.Thefts, orNull(record.LastTheft))83
fmt.Fprintf(output, " %-13s gulls %d, thefts %d, last theft %s\n", record.Beach, record.Gulls, record.Thefts, orNull(record.LastTheft))86
}84
}87
return nil85
return nil88
}86
}89
87
90
// day returns midnight UTC on a day in July 2026, the value a DATE column holds.88
// orNull formats a nullable field, or returns NULL when the field is nil.91
//92
// Takes date (int) which is the day of the month.93
//94
// Returns time.Time which is the start of that day.95
func day(date int) time.Time {96
return time.Date(2026, time.July, date, 0, 0, 0, 0, time.UTC)97
}98
99
// orNull formats a nullable field, or returns NULL when the field is nil. A date prints100
// as YYYY-MM-DD, and a decimal through its String method, which apd.Decimal declares on101
// its pointer.102
//89
//103
// Takes value (*T) which is a nullable field.90
// Takes value (*T) which is a nullable field.104
//91
//105
// Returns string which is the text to print.92
// Returns string which is the text to print.106
func orNull[T any](value *T) string {93
func orNull[T any](value *T) string {107
if value == nil {94
if value == nil {108
return "NULL"95
return "NULL"109
}96
}110
switch field := any(value).(type) {97
return fmt.Sprint(*value)111
case *time.Time:112
return field.Format(time.DateOnly)113
case fmt.Stringer:114
return field.String()115
default:116
return fmt.Sprint(*value)117
}118
}98
}Go type differences
The same SQL types map to different Go types, because each database reports them differently.
| Query | Field | MariaDB | SQLite |
|---|---|---|---|
| RecordTheft | parameter stolen_on | time.Time | string |
| FamilyTree | column generation | int32 | int64 |
| TheftLeague | column beach_thefts | *apd.Decimal | *int64 |
| BeachRecords | column last_theft | *time.Time | *string |