Dapper Guid 数组 IN 子句 MySql

Question

我正在尝试为 MySql 查询的 Guids 数组构建一个 IN 子句。 Guid 列在 DB 中表示为 binary(16)。根据这里的文档和答案，我应该能够做类似

var arrayOfGuidsFromDb = ...;

await dbconn.ExecuteAsync<T>("UPDATE ...
SET ...
WHERE SomeGuidField IN @Ids",
new { Ids = arrayOfGuidsFromDb }

我也在用这个 Guid 转换器

class MySqlGuidTypeHandler : SqlMapper.TypeHandler<Guid>
{
    public override void SetValue(IDbDataParameter parameter, Guid guid) => parameter.Value = guid.ToByteArray();

    public override Guid Parse(object value) => new Guid((byte[])value);
}

不过，MySql 的问题是它尝试（默认情况下）通过重新排列 GUID 值的时间戳部分来优化 DB 中的 GUID 布局。我决定不改变这种行为，它适用于读/写和WHERE SomeGuidField = @SomeGuid 等条件，但对于问题中的IN 语句，它匹配 0 个结果。我可以改写这个 hack

guids.Select(guid => $"uuid_to_bin('{RotateToMatchInDbGuid(guid).ToString()}')")

我将每个 guid 转换为字符串，然后将 string.Join(','... 转换为 IN 子句，即辅助方法：

static Guid RotateToMatchInDbGuid(Guid source)
    {
        Span<byte> result = stackalloc byte[16];
        source.TryWriteBytes(result);
        Swap(result, 0, 3);
        Swap(result, 1, 2);
        Swap(result, 4, 5);
        Swap(result, 6, 7);
        return new Guid(result);
    }

这显然看起来和感觉都不对。我是做错了什么，还是缺少一些设置，我应该启用以使 Dapper 行为在 = 和 IN GUID 条件下保持一致？

完整代码：

Guid[] guids = await dbConn.QueryAsync("SELECT Id FROM SomeTable"); //returns 1 row

// query using IN clause and array param:
var usingIn = await dbConn.QueryAsync("SELECT * From SomeTable WHERE Id IN @Ids", new { Ids = guids}); // returns 0 rows, should be 1

// now query using the `=` operator and same param but as a single value
var usingEquals = await dbConn.QueryAsync("SELECT * From SomeTable WHERE Id = @Id", new { Id = guids.First() }); // returns 1 row as expected

// query using array as CSV and no params
var usingCSV = await dbConn.QueryAsync($"SELECT * From SomeTable WHERE Id IN ({BuildCsv(guids)})"); // also returns 1 row as expected

Answer 1

IN 子句的参数化需要每个 IN 值一个参数；您不会将 CSV 字符串传递给单个参数 IN 并希望它能够解决

//no
Query("SELECT * FROM person WHERE name IN @names", new { names = "John,Jane,Mary" })

//yes
Query("SELECT * FROM person WHERE name IN (@name1,@name2,@name3)", new { name1 = "John", name2="Jane", name3="Mary" })

第一种形式只会找到名字字面意思是“John,Jane,Mary”的人

您也许可以使用 FIND IN SET：

Query("SELECT * FROM person WHERE FIND_IN_SET(name, @names) > 0", new { names = "John,Jane,Mary" })

但是有点蹩脚..