feat(schema): improve orm.schema.execute() to support executing bat…

…ches

When you run a batch of queries via `schema.execute()`, they are now grouped based on blank lines - a blank line between groups of statements means they will be executed separately. This is important for some queries that cannot be ran in a single batch, like when you create a database and switch to it.

packages/core/src/typings.ts

@@ -785,7 +785,7 @@ export interface ISchemaGenerator {
   updateSchema(options?: UpdateSchemaOptions): Promise<void>;
   getUpdateSchemaSQL(options?: UpdateSchemaOptions): Promise<string>;
   getUpdateSchemaMigrationSQL(options?: UpdateSchemaOptions): Promise<{ up: string; down: string }>;
-  createDatabase(name: string): Promise<void>;
+  createDatabase(name?: string): Promise<void>;
   dropDatabase(name?: string): Promise<void>;
   execute(sql: string, options?: { wrap?: boolean }): Promise<void>;
   ensureIndexes(): Promise<void>;

packages/core/src/utils/AbstractSchemaGenerator.ts

@@ -89,7 +89,7 @@ export abstract class AbstractSchemaGenerator<D extends IDatabaseDriver> impleme
   /**
    * creates new database and connects to it
    */
-  async createDatabase(name: string): Promise<void> {
+  async createDatabase(name?: string): Promise<void> {
     this.notImplemented();
   }
 

packages/knex/src/schema/SchemaHelper.ts

@@ -293,7 +293,8 @@ export abstract class SchemaHelper {
   }
 
   getCreateDatabaseSQL(name: string): string {
-    return `create database ${name}`;
+    // two line breaks to force separate execution
+    return `create database ${name};\n\nuse ${name}`;
   }
 
   getDropDatabaseSQL(name: string): string {

packages/knex/src/schema/SqlSchemaGenerator.ts

@@ -11,6 +11,7 @@ import {
   type EnsureDatabaseOptions,
   type DropSchemaOptions,
   type UpdateSchemaOptions,
+  type Transaction,
 } from '@mikro-orm/core';
 import type { CheckDef, ForeignKey, IndexDef, SchemaDifference, TableDifference } from '../typings';
 import { DatabaseSchema } from './DatabaseSchema';
@@ -536,11 +537,12 @@ export class SqlSchemaGenerator extends AbstractSchemaGenerator<AbstractSqlDrive
   /**
    * creates new database and connects to it
    */
-  override async createDatabase(name: string): Promise<void> {
+  override async createDatabase(name?: string): Promise<void> {
+    name ??= this.config.get('dbName')!;
     const sql = this.helper.getCreateDatabaseSQL('' + this.knex.ref(name));
 
     if (sql) {
-      await this.driver.execute(sql);
+      await this.execute(sql);
     }
 
     this.config.set('dbName', name);
@@ -554,21 +556,39 @@ export class SqlSchemaGenerator extends AbstractSchemaGenerator<AbstractSqlDrive
     await this.driver.execute(this.helper.getDropDatabaseSQL('' + this.knex.ref(name)));
   }
 
-  override async execute(sql: string, options: { wrap?: boolean } = {}) {
+  override async execute(sql: string, options: { wrap?: boolean; ctx?: Transaction } = {}) {
     options.wrap ??= false;
-    const lines = this.wrapSchema(sql, options).split('\n').filter(i => i.trim());
+    const lines = this.wrapSchema(sql, options).split('\n');
+    const groups: string[][] = [];
+    let i = 0;
+
+    for (const line of lines) {
+      if (line.trim() === '') {
+        if (groups[i]?.length > 0) {
+          i++;
+        }
+
+        continue;
+      }
 
-    if (lines.length === 0) {
+      groups[i] ??= [];
+      groups[i].push(line.trim());
+    }
+
+    if (groups.length === 0) {
       return;
     }
 
     if (this.platform.supportsMultipleStatements()) {
-      const query = lines.join('\n');
-      await this.driver.execute(query);
+      for (const group of groups) {
+        const query = group.join('\n');
+        await this.driver.execute(query);
+      }
+
       return;
     }
 
-    await Utils.runSerial(lines, line => this.driver.execute(line));
+    await Utils.runSerial(groups.flat(), line => this.driver.execute(line));
   }
 
   private wrapSchema(sql: string, options: { wrap?: boolean }): string {

packages/postgresql/src/PostgreSqlSchemaHelper.ts

@@ -29,6 +29,10 @@ export class PostgreSqlSchemaHelper extends SchemaHelper {
     return `set names '${charset}';\n${this.disableForeignKeysSQL()}\n\n`;
   }
 
+  override getCreateDatabaseSQL(name: string): string {
+    return `create database ${name}`;
+  }
+
   override getListTablesSQL(): string {
     return `select table_name, table_schema as schema_name, `
       + `(select pg_catalog.obj_description(c.oid) from pg_catalog.pg_class c