使用Dapper ORM检查记录是否存在的最简单方法是什么?
当我只想检查记录是否存在时,我真的需要为查询定义POCO对象吗?
发布于 2016-08-19 00:39:17
int id = ...
var exists = conn.ExecuteScalar<bool>("select count(1) from Table where Id=@id", new {id});
应该行得通..。
发布于 2017-04-13 06:32:16
我认为这可能会有更少的开销,因为没有函数调用或数据类型转换:
int id = ...
var exists = connection.Query<object>(
"SELECT 1 WHERE EXISTS (SELECT 1 FROM MyTable WHERE ID = @id)", new { id })
.Any();
发布于 2018-01-19 20:17:24
const string sql = "SELECT CAST(CASE WHEN EXISTS (SELECT 1 FROM MyTable WHERE Id = @Id) THEN 1 ELSE 0 END as BIT)";
bool exists = db.ExecuteScalar<bool>(sql, new { Id = 123 });
https://stackoverflow.com/questions/39006512
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