Compare · 005

From SQL types to Go types: MySQL and SQLite

Every file of the MySQL and SQLite versions side by side, with the lines that differ marked. 4 parameter or column types differ in Go.

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Configuration

sgl.yamldiffers
MySQL
SQLite
1version: 1
1version: 1
2
2
3databases:
3databases:
4 - name: landings
4 - name: landings
5 dialect: mysql
5 dialect: sqlite
6 migrations: db/migrations
6 migrations: db/migrations
7 queries: db/queries
7 queries: db/queries
8 go:
8 go:
9 package: store
9 package: store
10 out: internal/store
10 out: internal/store

Migrations

db/migrations/0001_landings.up.sqldiffers
MySQL
SQLite
1CREATE TABLE landings (
1CREATE TABLE landings (
2 id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
2 id INTEGER PRIMARY KEY,
3 species VARCHAR(50) NOT NULL,
3 species TEXT NOT NULL,
4 boxes SMALLINT NOT NULL,
4 boxes SMALLINT NOT NULL,
5 fish INT NOT NULL,
5 fish INTEGER NOT NULL,
6 weight_g BIGINT NOT NULL,
6 weight_g BIGINT NOT NULL,
7 length_cm DOUBLE NOT NULL,
7 length_cm REAL NOT NULL,
8 on_ice BOOLEAN NOT NULL,
8 on_ice BOOLEAN NOT NULL,
9 landed_at DATETIME NOT NULL,
9 landed_at DATETIME NOT NULL,
10 tag VARBINARY(16) NOT NULL,
10 tag BLOB NOT NULL,
11 notes TEXT,
11 notes TEXT
12 berth TINYINT UNSIGNED NOT NULL,
13 price_per_kg DECIMAL(6, 2) NOT NULL
14);
12);
db/migrations/0001_landings.down.sqlidentical
MySQL
SQLite
1DROP TABLE landings;
1DROP TABLE landings;

Queries

RecordLandingdiffers
MySQL · db/queries/landings.sql
SQLite · db/queries/landings.sql
1-- sgl.query(RecordLanding, execresult)
1-- sgl.query(RecordLanding, one)
2-- ?11 as sgl.param(price_per_kg, type: text)
2INSERT INTO landings (species, boxes, fish, weight_g, length_cm, on_ice, landed_at, tag, notes)
3INSERT INTO landings (species, boxes, fish, weight_g, length_cm, on_ice, landed_at, tag, notes, berth, price_per_kg)
3VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
4VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?);
4RETURNING id;
GetLandingdiffers
MySQL · db/queries/landings.sql
SQLite · db/queries/landings.sql
1-- sgl.query(GetLanding, one)
1-- sgl.query(GetLanding, one)
2SELECT id, species, boxes, fish, weight_g, length_cm, on_ice, landed_at, tag, notes, berth, price_per_kg
2SELECT id, species, boxes, fish, weight_g, length_cm, on_ice, landed_at, tag, notes
3FROM landings
3FROM landings
4WHERE id = ?;
4WHERE id = ?;

What sgl generates

RecordLandingdiffers
MySQL
SQLite
1func (queries *Queries) RecordLanding(ctx context.Context, params RecordLandingParams) (sql.Result, error)
1func (queries *Queries) RecordLanding(ctx context.Context, params RecordLandingParams) (RecordLandingRow, error)
2
2
3type RecordLandingParams struct {
3type RecordLandingParams struct {
4 Species string
4 Species string
5 Boxes int16
5 Boxes int64
6 Fish int32
6 Fish int64
7 WeightG int64
7 WeightG int64
8 LengthCm float64
8 LengthCm float64
9 OnIce bool
9 OnIce bool
10 LandedAt time.Time
10 LandedAt time.Time
11 Tag []byte
11 Tag []byte
12 Notes *string
12 Notes *string
13 Berth uint8
14 PricePerKg string
15}
13}
14
15type RecordLandingRow struct {
16 ID int64 `json:"id"`
17}
GetLandingdiffers
MySQL
SQLite
1func (queries *Queries) GetLanding(ctx context.Context, id int64) (GetLandingRow, error)
1func (queries *Queries) GetLanding(ctx context.Context, id int64) (GetLandingRow, error)
2
2
3type GetLandingRow struct {
3type GetLandingRow struct {
4 ID int64 `json:"id"`
4 ID int64 `json:"id"`
5 Species string `json:"species"`
5 Species string `json:"species"`
6 Boxes int16 `json:"boxes"`
6 Boxes int64 `json:"boxes"`
7 Fish int32 `json:"fish"`
7 Fish int64 `json:"fish"`
8 WeightG int64 `json:"weight_g"`
8 WeightG int64 `json:"weight_g"`
9 LengthCm float64 `json:"length_cm"`
9 LengthCm float64 `json:"length_cm"`
10 OnIce bool `json:"on_ice"`
10 OnIce bool `json:"on_ice"`
11 LandedAt time.Time `json:"landed_at"`
11 LandedAt time.Time `json:"landed_at"`
12 Tag []byte `json:"tag"`
12 Tag []byte `json:"tag"`
13 Notes *string `json:"notes"`
13 Notes *string `json:"notes"`
14 Berth uint8 `json:"berth"`
15 PricePerKg apd.Decimal `json:"price_per_kg"`
16}
14}

The program

example.godiffers
MySQL
SQLite
1package main
1package main
2
2
3import (
3import (
4 "context"
4 "context"
5 "database/sql"
5 "database/sql"
6 "fmt"
6 "fmt"
7 "io"
7 "io"
8 "time"
8 "time"
9
9
10 "seagull.sh/seagull/examples/mysql/005_type_mapping/internal/store"
10 "seagull.sh/seagull/examples/sqlite/005_type_mapping/internal/store"
11)
11)
12
12
13// run records a landing of fish and reads it back, printing the Go type sgl chose for
13// run records a landing of fish and reads it back, printing the Go type sgl chose for
14// each column. Seagull maps the type each column declares in db/migrations: SMALLINT, INT
14// each column. SQLite stores every value as one of five storage classes, so Seagull maps
15// and BIGINT give int16, int32 and int64, and an UNSIGNED integer gives the unsigned Go
15// the type each column declares in db/migrations. SMALLINT, INTEGER and BIGINT all have
16// type of the same width, so TINYINT UNSIGNED is uint8. DOUBLE gives float64, BOOLEAN
16// INTEGER affinity, which SQLite stores in up to eight bytes whatever width the column
17// (MySQL's TINYINT(1)) gives bool, DATETIME gives time.Time when the DSN sets
17// declares, so each gives int64, as the INTEGER PRIMARY KEY rowid does. REAL gives
18// parseTime=true, and VARBINARY gives []byte.
18// float64, and DATETIME gives time.Time, which the driver parses back from the text it
19//
19// stored. SQLite has no exact decimal type, so money is best kept as INTEGER pence; a
20// DECIMAL gives apd.Decimal from github.com/cockroachdb/apd/v3, which holds the exact
20// DECIMAL column maps to apd.Decimal from github.com/cockroachdb/apd/v3.
21// value. The insert binds the price as text instead, through sgl.param(price_per_kg,
22// type: text), and MySQL converts "4.20" to DECIMAL(6, 2) without rounding.
23//
21//
24// Takes database (*sql.DB) which is a migrated database.
22// Takes database (*sql.DB) which is a migrated database.
25// Takes output (io.Writer) which receives one line per column.
23// Takes output (io.Writer) which receives one line per column.
26//
24//
27// Returns error when a query fails.
25// Returns error when a query fails.
28func run(ctx context.Context, database *sql.DB, output io.Writer) error {
26func run(ctx context.Context, database *sql.DB, output io.Writer) error {
29 queries := store.New(database)
27 queries := store.New(database)
30
28
31 result, err := queries.RecordLanding(ctx, store.RecordLandingParams{
29 recorded, err := queries.RecordLanding(ctx, store.RecordLandingParams{
32 Species: "mackerel",
30 Species: "mackerel",
33 Boxes: 12,
31 Boxes: 12,
34 Fish: 480,
32 Fish: 480,
35 WeightG: 163_200,
33 WeightG: 163_200,
36 LengthCm: 31.5,
34 LengthCm: 31.5,
37 OnIce: true,
35 OnIce: true,
38 LandedAt: time.Date(2026, time.May, 1, 5, 30, 0, 0, time.UTC),
36 LandedAt: time.Date(2026, time.May, 1, 5, 30, 0, 0, time.UTC),
39 Tag: []byte{0x04, 0xa2, 0x19, 0xf3},
37 Tag: []byte{0x04, 0xa2, 0x19, 0xf3},
40 Notes: new("landed at Newlyn"),
38 Notes: new("landed at Newlyn"),
41 Berth: 7,
42 PricePerKg: "4.20",
43 })
39 })
44 if err != nil {
40 if err != nil {
45 return fmt.Errorf("recording a landing: %w", err)
41 return fmt.Errorf("recording a landing: %w", err)
46 }
42 }
47 id, err := result.LastInsertId()
48 if err != nil {
49 return fmt.Errorf("reading the landing's id: %w", err)
50 }
51
43
52 landing, err := queries.GetLanding(ctx, id)
44 landing, err := queries.GetLanding(ctx, recorded.ID)
53 if err != nil {
45 if err != nil {
54 return fmt.Errorf("getting landing %d: %w", id, err)
46 return fmt.Errorf("getting landing %d: %w", recorded.ID, err)
55 }
47 }
56 fmt.Fprintf(output, "id %-12T %d\n", landing.ID, landing.ID)
48 fmt.Fprintf(output, "id %-10T %d\n", landing.ID, landing.ID)
57 fmt.Fprintf(output, "species %-12T %s\n", landing.Species, landing.Species)
49 fmt.Fprintf(output, "species %-10T %s\n", landing.Species, landing.Species)
58 fmt.Fprintf(output, "boxes %-12T %d\n", landing.Boxes, landing.Boxes)
50 fmt.Fprintf(output, "boxes %-10T %d\n", landing.Boxes, landing.Boxes)
59 fmt.Fprintf(output, "fish %-12T %d\n", landing.Fish, landing.Fish)
51 fmt.Fprintf(output, "fish %-10T %d\n", landing.Fish, landing.Fish)
60 fmt.Fprintf(output, "weight_g %-12T %d\n", landing.WeightG, landing.WeightG)
52 fmt.Fprintf(output, "weight_g %-10T %d\n", landing.WeightG, landing.WeightG)
61 fmt.Fprintf(output, "length_cm %-12T %.1f\n", landing.LengthCm, landing.LengthCm)
53 fmt.Fprintf(output, "length_cm %-10T %.1f\n", landing.LengthCm, landing.LengthCm)
62 fmt.Fprintf(output, "on_ice %-12T %t\n", landing.OnIce, landing.OnIce)
54 fmt.Fprintf(output, "on_ice %-10T %t\n", landing.OnIce, landing.OnIce)
63 fmt.Fprintf(output, "landed_at %-12T %s\n", landing.LandedAt, landing.LandedAt.Format(time.RFC3339))
55 fmt.Fprintf(output, "landed_at %-10T %s\n", landing.LandedAt, landing.LandedAt.Format(time.RFC3339))
64 // %T prints []byte as []uint8, since byte is an alias for uint8.
56 // %T prints []byte as []uint8, since byte is an alias for uint8.
65 fmt.Fprintf(output, "tag %-12T % x\n", landing.Tag, landing.Tag)
57 fmt.Fprintf(output, "tag %-10T % x\n", landing.Tag, landing.Tag)
66 fmt.Fprintf(output, "notes %-12T %s\n", landing.Notes, *landing.Notes)
58 fmt.Fprintf(output, "notes %-10T %s\n", landing.Notes, *landing.Notes)
67 fmt.Fprintf(output, "berth %-12T %d\n", landing.Berth, landing.Berth)
68 fmt.Fprintf(output, "price_per_kg %-12T %s\n", landing.PricePerKg, landing.PricePerKg.String())
69 return nil
59 return nil
70}
60}

Go type differences

The same SQL types map to different Go types, because each database reports them differently.

QueryFieldMySQLSQLite
RecordLandingparameter boxesint16int64
RecordLandingparameter fishint32int64
GetLandingcolumn boxesint16int64
GetLandingcolumn fishint32int64