Question

我有这个查询，它是基于条件的多个选择的并集。问题是“AND”部分仅适用于最后一个选择，但我想将它应用于整个选择（所有联盟）

select * from
(select con.id_contact as  v,substr(concat(ifnull(con.firstname,''),ifnull(con.lastname,'')),1,4) as s0,   null as s1, null as s2 from contact con, fu_rec_group_link g
where con.id_contact = g.id_rec and id_group=125801) as tbl244295 where 1=1   UNION
select * from
(select con.id_contact as v,substr(concat(ifnull(con.firstname,''),ifnull(con.lastname,'')),1,4) as s0, null as s1, null as s2 from contact con, fu_rec_group_link g where
con.id_contact = g.id_rec and id_group=125803) as tbl244296 where 1=1 UNION
select * from
(select con.id_contact as  v,substr(concat(ifnull(con.firstname,''),ifnull(con.lastname,'')),1,4) as s0,  null as s1, null as s2 from contact con, fu_rec_group_link g where
con.id_contact = g.id_rec and id_group=126270) as tbl244297 where 1=1 AND v NOT IN
(select v from (select * from (select con.id_contact as v,substr(concat(ifnull(con.firstname,''),ifnull(con.lastname,'')),1,4) as s0, null as s1, null as s2 from contact con
where id_user=11944 and unregistered is not null) as tbl244299 where 1=1) as tblMinus )

Answer 1

正如@jarlh所指出的，对原始查询的修复是将联合包装在另一个选择中并将最后一个where条件应用于此。此外，当您使用union而不使用all时，您可以消除重复项，但这种方式可能会很昂贵;最好指定union all并使用distinct或group by子句来消除重复的行。

但是......看看你的查询它似乎可以简化得很简单并简化为下面的查询，它应该呈现相同的结果但表现更好。

select distinct
    con.id_contact as v, 
    substr(concat(ifnull(con.firstname,''),ifnull(con.lastname,'')),1,4) as s0, 
    null as s1, 
    null as s2 
from contact con
join fu_rec_group_link g on con.id_contact = g.id_rec 
where id_group in (125801, 125803, 126270)
and con.id_contact not in (
    select con.id_contact as v
    from contact con
    where id_user=11944 and unregistered is not null
)

由于既没有关于表格设计的任何信息，也没有任何用我的假设进行测试的数据可能完全不正确，如果是这样，我会立即删除答案。

Answer 2

在派生表中执行WHERE，将select * from ( select ... union select ... ) dt where dt.col ...置于其外部：

"P272": [
                {
                    "id": "q24871$4721C959-0FCF-49D4-9265-E4FAC217CB6E",
                    "mainsnak": {
                        "snaktype": "value",
                        "property": "P272",
                        "datatype": "wikibase-item",
                        "datavalue": {
                            "value": {
                                "entity-type": "item",
                                "numeric-id": 775450
                            },
                            "type": "wikibase-entityid"
                        }
                    },
                    "type": "statement",
                    "rank": "normal"
                },
                {
                    "id": "q24871$31777445-1068-4C38-9B4B-96362577C442",
                    "mainsnak": {
                        "snaktype": "value",
                        "property": "P272",
                        "datatype": "wikibase-item",
                        "datavalue": {
                            "value": {
                                "entity-type": "item",
                                "numeric-id": 3041294
                            },
                            "type": "wikibase-entityid"
                        }
                    },
                    "type": "statement",
                    "rank": "normal"
                },
                {
                    "id": "q24871$08009F7A-8E54-48C3-92D9-75DEF4CF3E8D",
                    "mainsnak": {
                        "snaktype": "value",
                        "property": "P272",
                        "datatype": "wikibase-item",
                        "datavalue": {
                            "value": {
                                "entity-type": "item",
                                "numeric-id": 646968
                            },
                            "type": "wikibase-entityid"
                        }
                    },
                    "type": "statement",
                    "rank": "normal"
                },
                {
                    "id": "q24871$CA53B5EB-1041-4701-A36E-7C348FAC984E",
                    "mainsnak": {
                        "snaktype": "value",
                        "property": "P272",
                        "datatype": "wikibase-item",
                        "datavalue": {
                            "value": {
                                "entity-type": "item",
                                "numeric-id": 434841
                            },
                            "type": "wikibase-entityid"
                        }
                    },
                    "type": "statement",
                    "rank": "normal",
                    "references": [
                        {
                            "hash": "50f57a3dbac4708ce4ae4a827c0afac7fcdb4a5c",
                            "snaks": {
                                "P143": [
                                    {
                                        "snaktype": "value",
                                        "property": "P143",
                                        "datatype": "wikibase-item",
                                        "datavalue": {
                                            "value": {
                                                "entity-type": "item",
                                                "numeric-id": 11920
                                            },
                                            "type": "wikibase-entityid"
                                        }
                                    }
                                ]
                            },
                            "snaks-order": [
                                "P143"
                            ]
                        }
                    ]
                }
            ],

sql union没有条件

2 个答案: