1. When multiple database connection components are added in Yii 2.0
'components' => [
'db' => [
'class' => 'yii\db\Connection',
'dsn' => 'mysql:host=62.234.135.47;dbname=pcs_api',
'username' => 'sq_pcs',
'password' => '',
'tablePrefix' => 'pa_',
'charset' => 'utf8mb4',
'enableSchemaCache' => false,
'schemaCacheDuration' => 3600,
'schemaCache' => 'redisCache',
],
'statDb' => [
'class' => 'yii\db\Connection',
'dsn' => 'mysql:host=62.234.135.47;dbname=pcs_stat',
'username' => 'sq_pcs',
'password' => '',
'tablePrefix' => 'ps_',
'charset' => 'utf8mb4',
],
],
2. The strategy for migrating multiple databases is to store the migrations in different directories. One connection component corresponds to one directory. The directory for db: /console/migrations/. The directory for statDb: /console/migrations/stat_db/. As shown in Figure 1

3. When generating a migration file under statDb, you need to specify: –migrationPath=@console/migrations/stat_db/ , as shown in Figure 2

PS E:\wwwroot\pcs-stat> ./yii migrate/create stat_task --migrationPath=@console/migrations/stat_db/
Yii Migration Tool (based on Yii v2.0.31)
Create new migration 'E:\wwwroot\pcs-stat/console/migrations/stat_db/\m200520_064341_stat_task.php'? (yes|no) [no]:yes
New migration created successfully.
4. You can then use the following commands to apply migrations to the respective databases. The first command will apply the migrations in the /console/migrations/ directory to the db database, while the second command will apply the migrations in /console/migrations/stat_db/ to the statDb database, and so on. Only one level of directory hierarchy is supported. As shown in Figure 3

PS E:\wwwroot\pcs-stat> ./yii migrate
Yii Migration Tool (based on Yii v2.0.31)
No new migrations found. Your system is up-to-date.
PS E:\wwwroot\pcs-stat> ./yii migrate --migrationPath=@console/migrations/stat_db/ --db=statDb
Yii Migration Tool (based on Yii v2.0.31)
Creating migration history table "ps_migration"...Done.
Total 2 new migrations to be applied:
m200519_065119_stat_task
m200519_071446_stat_resource
Apply the above migrations? (yes|no) [no]:no
PS E:\wwwroot\pcs-stat> ./yii migrate --migrationPath=@console/migrations/stat_db/ --db=statDb
Yii Migration Tool (based on Yii v2.0.31)
Creating migration history table "ps_migration"...Done.
Total 2 new migrations to be applied:
m200519_065119_stat_task
m200519_071446_stat_resource
Apply the above migrations? (yes|no) [no]:yes
*** applying m200519_065119_stat_task
> create table {{%stat_task}} ... done (time: 0.666s)
> create unique index uc_group_id_code_ca on {{%stat_task}} (group_id,code,created_at) ... done (time: 0.077s)
*** applied m200519_065119_stat_task (time: 1.016s)
*** applying m200519_071446_stat_resource
> create table {{%stat_resource}} ... done (time: 0.762s)
> create unique index uc_group_id_ca on {{%stat_resource}} (group_id,created_at) ... done (time: 0.081s)
*** applied m200519_071446_stat_resource (time: 1.113s)
2 migrations were applied.
Migrated up successfully.
5. Checking the migration history in the statDb database, it matches expectations. As shown in Figure 4

