SQLite 检查一行是否存在
问题描述：
我正在尝试检查我的 sqlite 数据库中名为Products"的表中是否存在特定 ID.
I'm trying to check if a specific ID exists in a table named "Products" in my sqlite database.
def existsCheck( db, id )
temp = db.execute( "select exists(
select 1
from Products
where promoID = ?
) ", [id] )
end
这是我当前的代码，但它返回一个数组，这意味着我必须先处理转换，然后才能将其用作布尔值.任何想法如何更改它以使其返回值为 1 的 int?
that's my current code but that returns an array which means I have to deal with conversion before I can use it as a boolean. Any ideas how I can change it so that it returns an int with the value 1?
答
无需使用子查询:
def existsCheck( db, id )
db.execute( "select 1
from Products
where promoID = ?",
[id] ).length > 0
end
这将返回一个布尔结果.
This returns a boolean result.