1. 通过if、case语句判断值：
select if(m.status = 1, "在库" , "借出") as status from machin_tool_ledger m
select CASE m.status WHEN 1 THEN '在库' ELSE '借出' END as status from machin_tool_ledger m
select CASE m.status WHEN 1 THEN '在库' when 0 then '借出' ELSE 'more' END as status from machin_tool_ledger m