fix: validate explicit migrations and preserve large business ids

internal/data/business/id_capacity.go

@@ -0,0 +1,62 @@
+package business
+
+import (
+	"fmt"
+	"strings"
+
+	"gorm.io/gorm"
+)
+
+func migrateBindingStatusIndex(db *gorm.DB) error {
+	const name = "idx_sys_user_bind_platform_status"
+	if !db.Migrator().HasTable(&bindingPO{}) {
+		return nil
+	}
+	if db.Migrator().HasIndex(&bindingPO{}, name) {
+		return nil
+	}
+	return db.Migrator().CreateIndex(&bindingPO{}, name)
+}
+
+// Preserve IDs and the high-water mark: lowering AUTO_INCREMENT could reuse
+// a deleted ID that still appears in historical records or external systems.
+func migratePromoteIDCapacity(db *gorm.DB) error {
+	if db.Dialector.Name() != "mysql" || !db.Migrator().HasTable("tab_promote") {
+		return nil
+	}
+	var column struct {
+		DataType, ColumnType, IsNullable, Extra, ColumnComment string
+	}
+	if err := db.Raw("SELECT data_type,column_type,is_nullable,extra,column_comment FROM information_schema.columns WHERE table_schema=DATABASE() AND table_name='tab_promote' AND column_name='id'").Scan(&column).Error; err != nil {
+		return err
+	}
+	if column.DataType == "bigint" {
+		return nil
+	}
+	if column.DataType != "int" || column.IsNullable != "NO" || column.Extra != "auto_increment" {
+		return fmt.Errorf("unexpected tab_promote.id definition; capacity migration stopped")
+	}
+	var next uint64
+	if err := db.Raw("SELECT auto_increment FROM information_schema.tables WHERE table_schema=DATABASE() AND table_name='tab_promote'").Scan(&next).Error; err != nil {
+		return err
+	}
+	typeName := "BIGINT"
+	if strings.Contains(column.ColumnType, "unsigned") {
+		typeName += " UNSIGNED"
+	}
+	// MySQL 5.7 rebuilds the table when widening an integer. Execute before
+	// starting writers and retain the original next ID and column comment.
+	return db.Connection(func(conn *gorm.DB) error {
+		var mode string
+		if err := conn.Raw("SELECT @@session.sql_mode").Scan(&mode).Error; err != nil {
+			return err
+		}
+		comment := column.ColumnComment
+		if !strings.Contains(mode, "NO_BACKSLASH_ESCAPES") {
+			comment = strings.ReplaceAll(comment, `\`, `\\`)
+		}
+		comment = "'" + strings.ReplaceAll(comment, "'", "''") + "'"
+		// MySQL does not permit a prepared-statement placeholder in COMMENT.
+		return conn.Session(&gorm.Session{NewDB: true}).Exec(fmt.Sprintf("ALTER TABLE tab_promote MODIFY COLUMN id %s NOT NULL AUTO_INCREMENT COMMENT %s, AUTO_INCREMENT=%d", typeName, comment, next)).Error
+	})
+}