你有没有碰到过有这样一种场景，就是我们需要看一下某个时间段内各种维度的汇总，比如这样：最近三年我们卖了多少货？有多少订单？平均交易价格多少？每个店铺卖了多少？交易成功的订单有多少？交易失败的订单有多少？ 等等…，假使这些数据的明细都在一个表内，该这么做呢？ 有没有简单方式？还有如何减少全表扫描以更改的拿到数据?
如果只是简单的利用聚合拿到数据可能您需要写很多sql，具体表现为每一个问题写一段sql 相互之间join起来，这样也许是个好主意，不过对于未充分优化的数据库系统，针对每一块的问题求解可能就是一个巨大的表扫描，当然还有一个问题就是重复的where条件，所以能不能把相同的where条件抽取出来以简化sql呢？让我们思考一下，也许有这样的解决办法~ （结论是有，当然有，哈哈哈~）
首先我提供下基本的表结构及测试数据
基本表结构
create table "order_info" ( "id" numeric(22) primary key , "oid" varchar(100) collate "pg_catalog"."default", -- 订单号 "shop" varchar(100) collate "pg_catalog"."default", -- 店铺 "date" date not null, --订单日期 "status" varchar(100) collate "pg_catalog"."default", -- 订单状态 "payment" numeric(18,2), -- 交易支付金额 "product" varchar(100) collate "pg_catalog"."default" -- 产品名称 );
初始化表数据
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217794', '16135476150276171', '店铺2', '2019-07-01', '交易失败', '139.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217761', '16132502190562224', '店铺2', '2020-05-01', '交易成功', '9.90', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217795', '16122384743927326', '店铺3', '2019-06-01', '交易失败', '357.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217796', '16138945194036971', '店铺2', '2019-05-01', '交易中', '59.90', '某某单品');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217797', '16131909251901209', '店铺1', '2019-04-01', '交易失败', '359.00', '某某赠品');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217798', '16135391935074761', '店铺2', '2019-03-01', '交易失败', '139.00', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217762', '16132472268456370', '店铺3', '2020-04-01', '交易成功', '79.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217763', '16122960304700879', '店铺2', '2020-03-01', '交易成功', '357.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217764', '16139491271154103', '店铺1', '2020-02-01', '交易成功', '139.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217765', '16122930818314343', '店铺2', '2020-01-01', '交易成功', '79.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217766', '12581133644786193', '店铺3', '2019-12-01', '交易成功', '79.00', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217767', '16122904539659361', '店铺2', '2019-11-01', '交易成功', '359.00', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217752', '16136227870425525', '店铺1', '2021-02-01', '交易成功', '4.90', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217753', '16139781339192958', '店铺2', '2021-01-01', '交易失败', '89.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217754', '16136217317281545', '店铺3', '2020-12-01', '交易中', '6.90', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217756', '16123091065663616', '店铺1', '2020-10-01', '交易失败', '95.00', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217757', '16123013684517817', '店铺2', '2020-09-01', '交易中', '79.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217758', '16139678011781848', '店铺3', '2020-08-01', '交易中', '59.90', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217759', '16139576187535157', '店铺2', '2020-07-01', '交易成功', '9.90', '某某单品04');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217791', '16132066938478413', '店铺4', '2019-10-01', '交易成功', '359.00', '某某单品05');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217792', '12589185047405699', '店铺5', '2019-09-01', '交易成功', '6.90', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217760', '16139601047542860', '店铺1', '2020-06-01', '交易成功', '359.00', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217837', '16138184483906283', '店铺4', '2021-03-04', '交易成功', '359.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217838', '16134581997874325', '店铺5', '2021-03-04', '交易成功', '299.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217839', '16131099658443817', '店铺3', '2021-03-04', '交易成功', '9.90', '某某单品04');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217840', '16131081649792689', '店铺2', '2021-03-04', '交易成功', '15.89', '某某单品05');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217841', '16131087729266410', '店铺1', '2021-03-04', '交易成功', '49.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217842', '16138126191679446', '店铺2', '2021-03-04', '交易成功', '6.90', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217843', '16138166422967430', '店铺3', '2021-03-04', '交易成功', '579.00', '某某单品');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217844', '16121412752067761', '店铺2', '2021-03-04', '交易成功', '359.00', '某某赠品');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217845', '12580980977280299', '店铺3', '2021-03-04', '交易成功', '359.00', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217799', '16135358470437562', '店铺2', '2019-02-01', '交易成功', '339.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217800', '16135320673129243', '店铺1', '2019-01-01', '交易成功', '299.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217801', '16131874317933316', '店铺2', '2021-03-04', '交易失败', '359.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217802', '16131792695743424', '店铺3', '2021-03-04', '交易中', '79.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217803', '16122278134767414', '店铺2', '2021-03-04', '交易失败', '99.00', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217804', '16131790093817033', '店铺3', '2021-03-04', '交易成功', '15.89', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217805', '16135230297238674', '店铺2', '2021-03-04', '交易成功', '247.81', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217806', '16135220588746073', '店铺1', '2021-03-04', '交易成功', '25.79', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217831', '16131159355051065', '店铺3', '2021-03-04', '交易成功', '359.00', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217832', '16131196017949185', '店铺2', '2021-03-04', '交易成功', '4.90', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217833', '16131207902538323', '店铺1', '2021-03-04', '交易成功', '339.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217834', '12580998687179491', '店铺2', '2021-03-04', '交易成功', '15.89', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217835', '16138210374123403', '店铺3', '2021-03-04', '交易成功', '189.00', '某某单品11');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217836', '16138242030068870', '店铺2', '2021-03-04', '交易成功', '39.90', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217846', '16134490408511254', '店铺3', '2021-03-04', '交易成功', '238.00', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217847', '16134370276544509', '店铺2', '2021-03-04', '交易成功', '100.00', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217854', '16121202131801564', '店铺1', '2021-03-04', '交易成功', '359.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217855', '16121178732153257', '店铺2', '2021-03-04', '交易成功', '499.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217856', '16130716264223504', '店铺3', '2021-03-04', '交易成功', '9.81', '某某单品11');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217857', '16130734211002184', '店铺2', '2021-03-04', '交易成功', '9.90', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217858', '16134100289526412', '店铺5', '2021-03-04', '交易成功', '359.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217859', '16134103486626066', '店铺3', '2021-03-04', '交易成功', '189.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217860', '16121142702989101', '店铺2', '2021-03-04', '交易成功', '259.00', '某某单品04');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217861', '16137767910421049', '店铺1', '2021-03-04', '交易成功', '299.00', '某某单品05');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217862', '16121018164688502', '店铺5', '2021-03-04', '交易成功', '299.00', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217887', '16120248152353139', '店铺3', '2021-03-04', '交易成功', '9.90', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217888', '16136951424489400', '店铺2', '2021-06-07', '交易成功', '9.90', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217889', '16136924750406856', '店铺1', '2021-05-07', '交易成功', '6.90', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217916', '16119522769335722', '店铺2', '2021-02-07', '交易中', '6.90', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217917', '12588728512745597', '店铺1', '2021-01-07', '交易成功', '89.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217848', '16138039330168579', '店铺2', '2021-03-04', '交易成功', '314.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217849', '16130922810196821', '店铺3', '2021-03-04', '交易失败', '199.00', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217890', '16136941319549862', '店铺2', '2021-04-07', '交易成功', '79.00', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217793', '16135470341712568', '店铺1', '2019-08-01', '交易成功', '180.00', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217755', '16132741910343927', '店铺2', '2020-11-01', '交易成功', '6.90', '某某单品11');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217807', '16138852921447547', '店铺2', '2021-03-04', '交易成功', '238.00', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217891', '16133225738639350', '店铺1', '2021-03-07', '交易失败', '49.00', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217850', '12591040185524596', '店铺2', '2021-03-04', '交易中', '6.90', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217851', '16130856267945884', '店铺3', '2021-03-04', '交易成功', '299.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217852', '16121205784010168', '店铺2', '2021-03-04', '交易失败', '19.70', '某某单品11');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217853', '16137863356208213', '店铺1', '2021-03-04', '交易中', '19.70', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217958', '12588659047949994', '店铺2', '2019-08-07', '交易成功', '9.90', '某某单品11');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217959', '16117515001200723', '店铺3', '2019-07-07', '交易成功', '99.00', '某某单品01');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217960', '16126968285988680', '店铺2', '2019-06-07', '交易成功', '6.90', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217985', '12588376827205292', '店铺3', '2019-05-07', '交易成功', '337.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217986', '12588344485529392', '店铺2', '2019-04-07', '交易成功', '139.00', '某某单品04');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217987', '16125503474522303', '店铺1', '2021-03-04', '交易失败', '9.81', '某某单品05');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217988', '16129065212801070', '店铺2', '2021-03-04', '交易中', '359.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217989', '16125466354777343', '店铺3', '2021-03-04', '交易中', '49.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217918', '16136147162483080', '店铺2', '2020-12-07', '交易成功', '6.90', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217919', '12580777996543594', '店铺3', '2020-11-07', '交易成功', '299.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217926', '16135916055519587', '店铺2', '2020-04-07', '交易成功', '359.00', '某某单品04');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217927', '16128748461350415', '店铺3', '2020-03-07', '交易成功', '9.90', '某某单品05');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217952', '16130772755076508', '店铺2', '2020-02-07', '交易成功', '139.00', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217953', '16130750443205377', '店铺4', '2020-01-07', '交易成功', '4.90', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217954', '16117587731623017', '店铺5', '2019-12-07', '交易成功', '4.90', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217955', '16127065063959102', '店铺3', '2019-11-07', '交易成功', '69.00', '某某单品02');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217920', '16128970251579383', '店铺2', '2020-10-07', '交易成功', '90.00', '某某单品03');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217921', '16128964832564531', '店铺2', '2020-09-07', '交易成功', '175.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217922', '16135999993916188', '店铺3', '2020-08-07', '交易成功', '139.00', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217923', '16136051439214988', '店铺2', '2020-07-07', '交易成功', '9.90', '某某单品06');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217924', '16119347018161682', '店铺5', '2020-06-07', '交易成功', '9.90', '某某单品07');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217925', '16132344851576556', '店铺3', '2020-05-07', '交易成功', '9.90', '某某单品08');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217956', '16130631650814848', '店铺2', '2019-10-07', '交易成功', '79.00', '某某礼盒');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217957', '16130549587928221', '店铺1', '2019-09-07', '交易成功', '6.90', '某某套装');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217990', '12590493961403993', '店铺2', '2021-03-04', '交易成功', '129.00', '某某单品');
insert into "order_info"("id", "oid", "shop", "date", "status", "payment", "product") values ('051802588006217991', '16115933800269974', '店铺1', '2021-03-04', '交易成功', '79.00', '某某赠品');
准备个问题
这里我找几个基本的问题，比如： 1.我们要找最近两年（2019、2020）有多少笔交易？+ 2.交易成功的平均价格多少？ + 3.交易成功的订单有多少？ + 4.店铺1、2、3分别卖了多少？
使用filter前
对于以上同类多维度数据求解这里推荐filter,可能熟悉同学大概会记得有这么个用法，不过我们还是简单的思考下：
如果我们将条件筛选放在一个查询里面(不含子查询及表连接) , 这样会在末尾where条件内放置公共条件, 随后我们使用filter对每个结果进行特定的筛选，也许就好了
ok，来尝试使用filter解决以下问题： 找最近两年（2019、2020）有多少笔交易？
问题求解
我们上面抛出了个问题： 找最近两年（2019、2020）有多少笔交易？
很显然这个结果集框定的范围是2019年和2020年 ，所以~
select
count(1) as 交易总订单_20_and_19,
count(1) filter ( where date>=to_date('2020-01-01','yyyy-mm-dd') and date < to_date('2021-01-01','yyyy-mm-dd') ) as 交易总订单_20,
count(1) filter ( where date>=to_date('2019-01-01','yyyy-mm-dd') and date < to_date('2020-01-01','yyyy-mm-dd') ) as 交易总订单_19
from order_info
where date >= date_trunc('year',to_date('2021-07-12','yyyy-mm-dd')+interval '-2 year')::date
and date < date_trunc('year',to_date('2021-07-12','yyyy-mm-dd'))::date
运行结果：
交易总订单_20_and_19 | 交易总订单_20 | 交易总订单_19
———————-+—————+—————
45 | 24 | 21
(1 row)
如果你是首次使用filter子句，这里我简单的验证下，就验证2019年多少订单吧：
select count(1) as 交易总订单_19 from order_info where date>=to_date(‘2019-01-01′,’yyyy-mm-dd’) and date < to_date(‘2020-01-01′,’yyyy-mm-dd’) ;
交易总订单_19
—————
21
(1 row)
【注意，不论您筛选的上面什么范围内的数据，一定要考虑 where条件一定要框定当前所有结果集合最大的范围，不然sql运行的结果不及预计~ 】
最后，对于一开始的问题给出一个参考sql：
select
count(1) as 交易总订单_20_and_19,
count(1) filter ( where date>=to_date('2020-01-01','yyyy-mm-dd') and date < to_date('2021-01-01','yyyy-mm-dd') ) as 交易总订单_20,
count(1) filter ( where date>=to_date('2019-01-01','yyyy-mm-dd') and date < to_date('2020-01-01','yyyy-mm-dd') ) as 交易总订单_19,
avg(payment) filter (where status='交易成功' ) as 交易成功的均价,
count(1) filter (where status='交易成功' ) as 交易成功的订单数,
count(1) filter (where status!='交易成功' ) as 交易失败的订单数,
sum(payment) filter (where status='交易成功' and shop='店铺1' ) as 店铺1交易额,
sum(payment) filter (where status='交易成功' and shop='店铺2' ) as 店铺2交易额,
sum(payment) filter (where status='交易成功' and shop='店铺3' ) as 店铺3交易额
from order_info
where date >= date_trunc('year',to_date('2021-07-12','yyyy-mm-dd')+interval '-2 year')::date
and date < date_trunc('year',to_date('2021-07-12','yyyy-mm-dd'))::date
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