[make cpp int = mysql row count]

I basically have a script, that let's me learn spells from an NPC, but if I am mounted, it doesn't let me learn spells

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        if (player->IsMounted())
        {
            player->GetSession()->SendAreaTriggerMessage("|cff87CEFAYou must get down of your mount.|r");
            CloseGossipMenuFor(player);
            return false;
        }

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I would like to turn the "if mounted" into a "if sql table has 30 or more rows"

I imagine it would be something like this, but I don't know the exact coding for it

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int a =  SELECT COUNT(*) FROM characters_spells

        if (int a >= 30)
        {
            player->GetSession()->SendAreaTriggerMessage("|cff87CEFAYou must get down of your mount.|r");
            CloseGossipMenuFor(player);
            return false;
        }
 

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Can anyone help out with the code for it please?