Fixed vercel session's lack of count override (fixes #3710)

drizzle-orm/src/vercel-postgres/session.ts

@@ -15,7 +15,7 @@ import type { SelectedFieldsOrdered } from '~/pg-core/query-builders/select.type
 import type { PgQueryResultHKT, PgTransactionConfig, PreparedQueryConfig } from '~/pg-core/session.ts';
 import { PgPreparedQuery, PgSession } from '~/pg-core/session.ts';
 import type { RelationalSchemaConfig, TablesRelationalConfig } from '~/relations.ts';
-import { fillPlaceholders, type Query, sql } from '~/sql/sql.ts';
+import { fillPlaceholders, type Query, type SQL, sql } from '~/sql/sql.ts';
 import { type Assume, mapResultRow } from '~/utils.ts';
 
 export type VercelPgClient = VercelPool | VercelClient | VercelPoolClient;
@@ -181,6 +181,12 @@ export class VercelPgSession<
 		return this.client.query<T>(query, params);
 	}
 
+	override async count(sql: SQL): Promise<number> {
+		const result = await this.execute(sql);
+
+		return Number((result as any)['rows'][0]['count']);
+	}
+
 	override async transaction<T>(
 		transaction: (tx: VercelPgTransaction<TFullSchema, TSchema>) => Promise<T>,
 		config?: PgTransactionConfig | undefined,