From f89b8115dd34f61ca39e818d480062fe49aa7158 Mon Sep 17 00:00:00 2001
From: AJ ONeal <aj@therootcompany.com>
Date: Thu, 9 Apr 2026 02:14:16 -0600
Subject: [PATCH] feat(mymigrate): add MySQL/MariaDB backend for sqlmigrate

---
 database/sqlmigrate/mymigrate/go.mod       |  10 ++
 database/sqlmigrate/mymigrate/go.sum       |   6 ++
 database/sqlmigrate/mymigrate/mymigrate.go | 110 +++++++++++++++++++++
 3 files changed, 126 insertions(+)
 create mode 100644 database/sqlmigrate/mymigrate/go.mod
 create mode 100644 database/sqlmigrate/mymigrate/go.sum
 create mode 100644 database/sqlmigrate/mymigrate/mymigrate.go

diff --git a/database/sqlmigrate/mymigrate/go.mod b/database/sqlmigrate/mymigrate/go.mod
new file mode 100644
index 0000000..cbf6195
--- /dev/null
+++ b/database/sqlmigrate/mymigrate/go.mod
@@ -0,0 +1,10 @@
+module github.com/therootcompany/golib/database/sqlmigrate/mymigrate
+
+go 1.26.1
+
+require (
+	github.com/go-sql-driver/mysql v1.9.3
+	github.com/therootcompany/golib/database/sqlmigrate v1.0.1
+)
+
+require filippo.io/edwards25519 v1.1.0 // indirect
diff --git a/database/sqlmigrate/mymigrate/go.sum b/database/sqlmigrate/mymigrate/go.sum
new file mode 100644
index 0000000..97b55e2
--- /dev/null
+++ b/database/sqlmigrate/mymigrate/go.sum
@@ -0,0 +1,6 @@
+filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
+filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
+github.com/go-sql-driver/mysql v1.9.3 h1:U/N249h2WzJ3Ukj8SowVFjdtZKfu9vlLZxjPXV1aweo=
+github.com/go-sql-driver/mysql v1.9.3/go.mod h1:qn46aNg1333BRMNU69Lq93t8du/dwxI64Gl8i5p1WMU=
+github.com/therootcompany/golib/database/sqlmigrate v1.0.1 h1:yhQb4KSwSny1WSC1Y1Z6oHT7V1lznKuj1vzZkF6MqFo=
+github.com/therootcompany/golib/database/sqlmigrate v1.0.1/go.mod h1:7PQUjwT78Hx+SftcIKI2PH4zSFlrSO0V9h618PJqC38=
diff --git a/database/sqlmigrate/mymigrate/mymigrate.go b/database/sqlmigrate/mymigrate/mymigrate.go
new file mode 100644
index 0000000..507d255
--- /dev/null
+++ b/database/sqlmigrate/mymigrate/mymigrate.go
@@ -0,0 +1,110 @@
+// Package mymigrate implements sqlmigrate.Migrator for MySQL and MariaDB
+// using database/sql with github.com/go-sql-driver/mysql.
+//
+// The *sql.DB must be opened with multiStatements=true in the DSN;
+// without it, multi-statement migration files will silently execute only
+// the first statement. The multiStatements requirement is validated lazily
+// on the first ExecUp or ExecDown call:
+//
+//	db, err := sql.Open("mysql", "user:pass@tcp(host:3306)/dbname?multiStatements=true")
+//
+// MySQL and MariaDB do not support transactional DDL. Statements like
+// CREATE TABLE and ALTER TABLE cause an implicit commit, so if a migration
+// fails partway through, earlier DDL statements in that migration will
+// already be committed. DML-only migrations are fully transactional.
+package mymigrate
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"github.com/go-sql-driver/mysql"
+
+	"github.com/therootcompany/golib/database/sqlmigrate"
+)
+
+// Migrator implements sqlmigrate.Migrator using a *sql.DB with MySQL/MariaDB.
+type Migrator struct {
+	DB        *sql.DB
+	validated bool
+}
+
+// New creates a Migrator from the given database handle.
+// The multiStatements=true DSN requirement is validated lazily on the
+// first ExecUp or ExecDown call.
+func New(db *sql.DB) *Migrator {
+	return &Migrator{DB: db}
+}
+
+var _ sqlmigrate.Migrator = (*Migrator)(nil)
+
+// ExecUp runs the up migration SQL in a transaction. DDL statements
+// (CREATE, ALTER, DROP) are implicitly committed by MySQL; see package docs.
+func (m *Migrator) ExecUp(ctx context.Context, mig sqlmigrate.Migration) error {
+	return m.exec(ctx, mig.Up)
+}
+
+// ExecDown runs the down migration SQL in a transaction. DDL statements
+// (CREATE, ALTER, DROP) are implicitly committed by MySQL; see package docs.
+func (m *Migrator) ExecDown(ctx context.Context, mig sqlmigrate.Migration) error {
+	return m.exec(ctx, mig.Down)
+}
+
+func (m *Migrator) exec(ctx context.Context, sqlStr string) error {
+	if !m.validated {
+		// Probe for multi-statement support. Without it, migration files
+		// that contain more than one statement silently execute only the first.
+		if _, err := m.DB.ExecContext(ctx, "DO 1; DO 1"); err != nil {
+			return fmt.Errorf(
+				"%w: mymigrate: migration requires multiStatements=true in the MySQL DSN",
+				sqlmigrate.ErrExecFailed,
+			)
+		}
+		m.validated = true
+	}
+
+	tx, err := m.DB.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("%w: begin: %w", sqlmigrate.ErrExecFailed, err)
+	}
+	defer func() { _ = tx.Rollback() }()
+
+	if _, err := tx.ExecContext(ctx, sqlStr); err != nil {
+		return fmt.Errorf("%w: exec: %w", sqlmigrate.ErrExecFailed, err)
+	}
+
+	if err := tx.Commit(); err != nil {
+		return fmt.Errorf("%w: commit: %w", sqlmigrate.ErrExecFailed, err)
+	}
+
+	return nil
+}
+
+// Applied returns all applied migrations from the _migrations table.
+// Returns an empty slice if the table does not exist (MySQL error 1146).
+func (m *Migrator) Applied(ctx context.Context) ([]sqlmigrate.AppliedMigration, error) {
+	rows, err := m.DB.QueryContext(ctx, "SELECT id, name FROM _migrations ORDER BY name")
+	if err != nil {
+		if mysqlErr, ok := errors.AsType[*mysql.MySQLError](err); ok && mysqlErr.Number == 1146 {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("%w: %w", sqlmigrate.ErrQueryApplied, err)
+	}
+	defer rows.Close()
+
+	var applied []sqlmigrate.AppliedMigration
+	for rows.Next() {
+		var a sqlmigrate.AppliedMigration
+		if err := rows.Scan(&a.ID, &a.Name); err != nil {
+			return nil, fmt.Errorf("%w: scanning row: %w", sqlmigrate.ErrQueryApplied, err)
+		}
+		applied = append(applied, a)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("%w: reading rows: %w", sqlmigrate.ErrQueryApplied, err)
+	}
+
+	return applied, nil
+}