SQL UNION 操作符的應用

union操作符用於合併兩個或多個select語句的結果集。但是要注意的是union連線的前後select語句查詢的字段要一致。

union是取不同的值,也就是不能重複的值。

2.union all

union all 可以取重複的值。

第乙個例子是查詢所有的字段，例子如下：

select a.id, a.in_out_flag, a.document_number, a.document_date, a.warehouse_id, a.bill_type, a.storeman_id, a.purpose, a.illustrate, a.type, a.counterparty_code, a.bill_number, a.agency_department, a.operator, a.create_by, a.create_time, a.update_by, a.update_time, a.remark, a.del_flag, a.confirm_flag, a.project_number, a.order_no, k.username as "storemanname", s3.user_name as "operatorname", d.dept_name as "agencydepartmentname", w.warehouse_name as "warehousename", w.warehouse_code as "warehousecode" from (select *from inv_bill union all select *from inv_bill_out ) aleft join inv_warehouse_keeper k on a.storeman_id = k.id left join sys_user s3 on a.operator = s3.user_id left join sys_dept d on a.agency_department = d.dept_id left join inv_warehouse_def w on a.warehouse_id = w.id where a.confirm_flag = '1'

and a.del_flag = '0'

第二例子根據想要的條件進行返回結果集，例子如下：

select a.id as "id", a.in_out_flag as "inoutflag", a.document_number as "documentnumber", a.document_date as "documentdate", a.bill_type as "billtype", a.username as "storemanname", a.quantity as "quantity", a.user_name as "operatorname", a.counterparty_code as "counterpartycode", a.material_code as "materialcode", a.material_name as "materialname", a.confirm_flag as "confirmflag", a.del_flag as "delflag", a.warehouse_name as "warehousename", a.warehouse_code as "warehousecode" from (select a.id, a.in_out_flag, a.document_number, a.document_date, a.bill_type, k.username, d.quantity, s3.user_name, a.counterparty_code, d.material_code, d.material_name, a.confirm_flag, a.del_flag, w.warehouse_name, w.warehouse_code from inv_bill_detail d left join inv_bill a on a.id = d.warehouse_bill_id left join inv_warehouse_keeper k on a.storeman_id = k.id left join sys_user s3 on a.operator = s3.user_id left join inv_warehouse_def w on a.warehouse_id = w.id union all select a.id, a.in_out_flag, a.document_number, a.document_date, a.bill_type, k.username, d.quantity, s3.user_name, a.counterparty_code, d.material_code, d.material_name, a.confirm_flag, a.del_flag, w.warehouse_name, w.warehouse_code from inv_bill_detail_out d left join inv_bill_out a on a.id = d.warehouse_bill_id left join inv_warehouse_keeper k on a.storeman_id = k.id left join sys_user s3 on a.operator = s3.user_id left join inv_warehouse_def w on a.warehouse_id = w.id ) awhere a.confirm_flag = '1'

and a.del_flag = '0'

SQL UNION 操作符的應用

SQL UNION 和 UNION ALL 操作符

SQL UNION 和UNION ALL 操作符

SQL UNION 和 UNION ALL 操作符

SQL UNION 操作符的應用

SQL UNION 和 UNION ALL 操作符

SQL UNION 和UNION ALL 操作符

SQL UNION 和 UNION ALL 操作符

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