[MySQL] Add fetch_optional, fix encode/decode for integers

tests/mysql-types.rs

@@ -0,0 +1,30 @@
+use sqlx::{Connection, MariaDb, Row};
+use std::env;
+
+macro_rules! test {
+    ($name:ident: $ty:ty: $($text:literal == $value:expr),+) => {
+        #[async_std::test]
+        async fn $name () -> sqlx::Result<()> {
+            let mut conn =
+                Connection::<MariaDb>::open(&env::var("DATABASE_URL").unwrap()).await?;
+
+            $(
+                let row = sqlx::query(&format!("SELECT {} = ?, ?", $text))
+                    .bind($value)
+                    .bind($value)
+                    .fetch_one(&mut conn)
+                    .await?;
+
+                assert_eq!(row.get::<i32>(0), 1);
+                assert!($value == row.get::<$ty>(1));
+            )+
+
+            Ok(())
+        }
+    }
+}
+
+test!(mysql_bool: bool: "false" == false, "true" == true);
+test!(mysql_long: i32: "2141512" == 2141512_i32);
+
+