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Unknown Column In Where Clause（16个答案）
3天前关闭。
我合并2表中的数据在查询中显示分页，但在第二个查询中的过滤器，我没有在第二个查询中的客户端名称，但当我过滤的数据第二个表中的数据出现，所以我想添加不为空，但得到未知的列错误。

(
select 
    `linguists`.`id` as `linguist_id`, 
    CONCAT(linguists.first_name," ", linguists.last_name) AS linguist_name, 
    `reps`.`id` as `rep_id`, 
    CONCAT(reps.first_name, " ", reps.last_name) AS rep_name, 
    `clients`.`id` as `client_id`, 
    `clients`.`name` as `client_name`, 
    `clients`.`type` as `client_type`, 
    `invoices`.`booking_id`, 
    NULL AS id, 
    `bookings`.`booking_date`, 
    `invoices`.`client_paid`, 
    `invoices`.`linguist_paid`, 
    `invoices`.`demand_letter_id`, 
    `invoices`.`reminder_1`, 
    `invoices`.`reminder_2`, 
    `invoices`.`reminder_3`,
    `invoices`.`reminder_4`, 
    `invoices`.`exceptional_case`, 
    bookings.source_company AS scope, 
    `bookings`.`credit_note`, 
    DATEDIFF(CURDATE(), invoices.created_at) AS days_since_invoice, 
    NULL AS start_date, 
    NULL AS end_date 
from `invoices` 
left join `bookings` on `bookings`.`id` = `invoices`.`booking_id` 
left join `clients` on `clients`.`id` = `bookings`.`client_id` 
left join `reps` on `reps`.`id` = `bookings`.`rep_id` 
left join `linguists` on `linguists`.`id` = `bookings`.`linguist_id` 
where 
    (
        `clients`.`name` like '%t%' 
    or 
        `clients`.`id` = 't'
    ) 
and `invoices`.`linguist_paid` is null 
and `invoices`.`invoice_submitted_linguist` < '2023-04-12' 
and `bookings`.`source_company` = 'UKLS'
) 

union all 
(
 select 
    `linguist_id`, 
    CONCAT(linguists.first_name, " ", linguists.last_name) AS linguist_name, 
    NULL AS rep_id, 
    NULL AS rep_name, 
    NULL AS client_id, 
    NULL AS client_name, 
    NULL AS client_type, 
    `on_demand_linguist_invoice`.`id`, 
    NULL AS booking_id, 
    NULL AS booking_date, 
    NULL AS client_paid, 
    `linguist_paid`, 
    NULL AS demand_letter_id, 
    NULL AS reminder_1, 
    NULL AS reminder_2, 
    NULL AS reminder_3, 
    NULL AS reminder_4, 
    NULL AS exceptional_case, 
    NULL AS scope, 
    NULL AS credit_note, 
    DATEDIFF(CURDATE(), on_demand_linguist_invoice.created_at) AS days_since_invoice, 
    `on_demand_linguist_invoice`.`start_date`, 
    `on_demand_linguist_invoice`.`end_date` 
from `on_demand_linguist_invoice` 
left join `linguists` on `linguists`.`id` = `on_demand_linguist_invoice`.`linguist_id` 
where 
    (
        client_name is not null
    ) 
    and `on_demand_linguist_invoice`.`linguist_paid` is null 
    and `on_demand_linguist_invoice`.`invoice_submitted_linguist` < '2023-04-12'
)

我尝试使用where client_name不为null，因此第二个表数据不会出现，因为我在select中选择了NULL作为client_name，但在“where子句”中获得了未知列“client_name”