The biggest misconception with solar covers or rings is that they are meant to heat the pool. While these products may raise the pool temperature, they do so by reducing heat loss (mainly at night). Solar blankets should not be left on a pool during daylight hours, and at the very least, they should be removed for a 4-8 hours during the day for the pool to breathe.
ALTER DATABASE ... SET autocommit = 1 causes an implicit commit if the value was 0. All these statements cause an implicit commit before execution. This means that, even if the statement fails with an error, the transaction is committed. Some of them, like CREATE TABLE ... SELECT, also cause a commit immediatly after execution.
Contract promises which are not supported by consideration are generally not enforceable. In fact, the requirement of consideration is what distinguishes a contract from a mere gift. If one party merely promises goods to another party without requiring them to do something in exchange, the transaction would be a gift and not a contract.