[英]Subquery of select statement with Knex.js
我正在嘗試使用Knex使用子查詢創建以下查詢:
SELECT
t.*,
(SELECT COUNT(*) FROM team_users tu WHERE TeamID = t.ID) AS UserCount,
(SELECT COUNT(*) FROM team_access ta WHERE TeamID = t.ID) AS AppCount
FROM teams t WHERE OwnerUserID = _UserID;
結果應該是team表,其中包含來自不同表的UserCount和AppCount的計數聚合(team_users,team_access)
id | Name | OwnerUserID | UserCount | AppCount
-----------------------------------------------------
134| Team A | 1538 | 7 | 6
135| Team B | 1538 | 4 | 2
136| Team C | 1538 | 12 | 1
我認為是一個等效的knex實現是:
var subquery1 = Knex.knex('team_users').count('*').where('TeamID', 'teams.ID').as('UserCount');
var subquery2 = Knex.knex('team_access').count('*').where('TeamID', 'teams.ID').as('AppCount');
Knex.knex.select('*', subquery1, subquery2).from('teams').where("OwnerUserID", ownerId).asCallback(dataSetCallback);
運行它,我確實在返回的對象中得到“UserCount”和“AppCount”列但總是為零,可能是因為它沒有識別子查詢中的'teams.ID'。
我設法使用Knex.raw函數解決它:
Knex.knex('teams')
.select('*', Knex.knex.raw('(SELECT COUNT(*) FROM team_users WHERE TeamID = teams.ID) AS UserCount'), Knex.knex.raw('(SELECT COUNT(*) FROM team_access WHERE TeamID = teams.ID) AS AppCount'))
.where("OwnerUserID", ownerId)
.asCallback(dataSetCallback);
但我很想知道如何使用子查詢對象實現這一點。
您正在嘗試將teams.ID
字符串作為值傳遞。 為了能夠做.where('columnName', 'otherColumnName')
,必須使用knex.ref
將otherColumnName
作為標識符傳遞。
var teamsIdColumnIdentifier = knex.ref('teams.ID'); // <-- [1]
var subquery1 = Knex.knex('team_users').count('*')
.where('TeamID', teamsIdColumnIdentifier).as('UserCount');
var subquery2 = Knex.knex('team_access').count('*')
.where('TeamID', teamsIdColumnIdentifier).as('AppCount');
Knex.knex.select('*', subquery1, subquery2).from('teams')
.where("OwnerUserID", ownerId).asCallback(dataSetCallback);
[1]之前knex.ref
加入Knex在5月2018年 ,你不得不使用knex.raw
,像這樣;
var teamsIdColumnIdentifier = knex.raw('??', ['teams.ID']);
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