tools: cleanup entries from the hardcoded skip_files list in common.v (used by v test, v test-self etc); use the new // vtest build: syntax to mark the tests instead (#23918)

examples/database/mysql.v

@@ -1,3 +1,4 @@
+// vtest build: !(macos || windows)
 import db.mysql
 
 fn main() {

examples/database/orm.v

@@ -1,3 +1,4 @@
+// vtest build: !(macos || windows)
 import os
 import db.sqlite
 import db.mysql

examples/database/psql/customer.v

@@ -1,10 +1,7 @@
+// vtest build: linux
 module main
 
-/*
 import db.pg
-*/
-
-const dash = '----------------------------------------------------------------'
 
 struct Customer {
 	id        int
@@ -13,53 +10,62 @@ struct Customer {
 	country   string
 }
 
+const dash = '----------------------------------------------------------------'
+
 fn main() {
-	/*
-	db := pg.connect(pg.Config{
-		host: 'localhost' //'127.0.0.1'
-		user: 'postgres'
+	db := pg.connect(
+		host:   'localhost' // or '127.0.0.1'
+		user:   'postgres'
 		dbname: 'customerdb'
-	}) or {
-		println('failed to connect')
-		println(err)
+	) or {
+		eprintln('failed to connect, error: ${err}')
 		return
 	}
 
-	nr_customers := db.select count from Customer
-	println('Total customers: $nr_customers')
+	nr_customers := sql db {
+		select count from Customer
+	}!
+	println('Total customers: ${nr_customers}')
 
-	// V syntax can be used to build queries
 	println(dash)
 	bg_country := 'Bulgaria'
-	bg_customers := db.select from Customer where country == bg_country  && id != 2
+	// V syntax can be used to build queries
+	bg_customers := sql db {
+		select from Customer where country == bg_country && id != 2
+	}!
 	for customer in bg_customers {
-		println('$customer.country | $customer.id - $customer.name')
+		println('${customer.country} | ${customer.id} - ${customer.name}')
 	}
 
 	println(dash)
-	ru_customers := db.select from Customer where country == 'Russia'
+	ru_customers := sql db {
+		select from Customer where country == 'Russia'
+	}!
 	for customer in ru_customers {
-		println('$customer.country | $customer.id - $customer.name')
+		println('${customer.country} | ${customer.id} - ${customer.name}')
 	}
 
 	// by adding `limit 1` we tell V that there will be only one object
 	println(dash)
-	existing := db.select from Customer where id == 1 limit 1 or { panic(err) }
-	println('Existing customer name: $existing.name')
+	existing := sql db {
+		select from Customer where id == 1 limit 1
+	}!
+	println('Existing customer name: ${existing}[0].name')
 	println('Existing customer full information:')
 	println(existing)
 
 	println(dash)
 	q := Customer{}
 	// It's easy to handle queries that don't return any data
-	if anon := db.select from Customer where id == 12345 && name == q.name &&
-			nr_orders > q.nr_orders limit 1 {
-		println('Non existing customer name: $anon.name')
-	}
+	_ := sql db {
+		select from Customer where id == 12345 && name == q.name && nr_orders > q.nr_orders limit 1
+	}!
 	// Insert a new customer
 	nc := Customer{
-		name: 'John Doe'
+		name:      'John Doe'
 		nr_orders: 10
 	}
-	db.insert(nc)*/
+	sql db {
+		insert nc into Customer
+	}!
 }