postgresql - go-pg UnionAll - 限制整个表达式

Question

我正在尝试在 go-pg 中使用 .UnionAll 方法golang 库。

    var model []Customer
    q0 := db.Model(&model).Where("name = ?", name0).Limit(4)
    q1 := db.Model(&model).Where("name = ?", name1).Limit(3)
    var result []Customer
    if err := q0.UnionAll(q1).Limit(1).Select(&result); !as.NoError(err) {
        return
    }

此代码生成查询:

(SELECT "customer"."id", "customer"."name" FROM customers AS "customer" WHERE (name = 'customer 1deificatory zonoid reprepare alacrify serenissime') 
LIMIT 1) 
UNION ALL 
(SELECT "customer"."id", "customer"."name" FROM customers AS "customer" WHERE (name = 'customer 2fordless ferroboron radiability dandizette smutch'
LIMIT 3)
)

但我希望它是:

(SELECT "customer"."id", "customer"."name" FROM customers AS "customer" WHERE (name = 'customer 1deificatory zonoid reprepare alacrify serenissime') 
LIMIT 4) 
UNION ALL 
(SELECT "customer"."id", "customer"."name" FROM customers AS "customer" WHERE (name = 'customer 2fordless ferroboron radiability dandizette smutch')
LIMIT 3)

LIMIT 1

那么如何使用 go-pg 获取我期望的原始 SQL 查询呢？问题是出于某种原因我无法将 Limit 1 表达式应用于整个查询。此外，我的 Limit 4 未正确应用于第一个 union all 成员。我的整个代码是 here .

Answer 1

我相信这个查询对您有用。

if err := db.Model().With("union_q", q0.UnionAll(q1)).Table("union_q").Limit(1).Select(&result); !as.NoError(err) {
    return
}

查询并不完全是您想要的，据我所知，当前版本的 go-pg 无法生成该查询。但这个查询完全符合您的要求。