Question

我使用OrmLite进行以下自定义SQL查询：

var results = db.Select<Tuple<Customer,Purchase>>(@"SELECT c.*, 0 EOT, p1.*
    FROM customer c
    JOIN purchase p1 ON (c.id = p1.customer_id)
    LEFT OUTER JOIN purchase p2 ON (c.id = p2.customer_id AND 
        (p1.date < p2.date OR p1.date = p2.date AND p1.id < p2.id))
    WHERE p2.id IS NULL;");

添加可选WHERE子句的最佳方法是，例如，当字段有值时过滤给定的客户名称字段，或者为查询添加分页？

Answer 1

如果您正在使用自定义SQL，则只需自己构建其他查询，例如：

var sql = @"SELECT c.*, 0 EOT, p1.*
    FROM customer c
    JOIN purchase p1 ON (c.id = p1.customer_id)
    LEFT OUTER JOIN purchase p2 ON (c.id = p2.customer_id AND 
        (p1.date < p2.date OR p1.date = p2.date AND p1.id < p2.id))
    WHERE p2.id IS NULL";

//string name = "Customer Name";
string name = null;
if (name != null)
{
    sql += "\nAND name = @name";
}

int? limit = 100;
if (limit != null)
{
    sql += $"\nLIMIT {limit}";
}

var results = db.Select<Tuple<Customer,Purchase>>(sql, new { name });

A Live Example of this is available on Gistlyn。

参数化ServiceStack自定义SQL查询

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