英文:
Is it possible to use SQL IIF function in GORM?
问题
我有一个用于作业的表格，一个用于解决方案的表格，还有一个用于学生的表格。
我想检索所有的作业，并针对每个作业添加一个“标志”，显示当前登录的学生是否尝试了该作业。
我尝试了这个：
import ("fmt""gorm.io/gorm""encoding/json""github.com/my_organisation/myorg-repo/db")var database *gorm.DBvar solutions []db.Solutionvar listOfAsnmtIDs []uintfunc myfuncn (w http.ResponseWriter, r *http.Request){//..._ = database.Table("solutions").Where("pupil_id = ?",pupil.ID).Select("assignment_id").Find(&solutions)for _, solution := range solutions {listOfAsnmtIDs = append(listOfAsnmtIDs, solution.AssignmentID)}response := database.Table("assignments").Select(`id, created_at, IIF((id IN ?), 'attempted', 'Not attempted') as attempted`, listOfAsnmtIDs).Find(&allAssignments)if response.RowsAffected < 1 {respondToClient(w, 404, nil, "No assignments found")return}//...}
请注意，我只翻译了代码部分，其他内容不包括在内。
英文:
I have a a table for assignments, one for solutions and another for students.
I want to retrieve all assignments and against each I want to add a 'flag' showing that the currently logged-in student has attempted the assignment or not.
I have tried this:
import ("fmt""gorm.io/gorm""encoding/json""github.com/my_organisation/myorg-repo/db")var database *gorm.DBvar solutions []db.Solutionvar listOfAsnmtIDs []uintfunc myfuncn (w http.ResponseWriter, r *http.Request){//..._ = database.Table("solutions").Where("pupil_id = ?",pupil.ID).Select("assignment_id").Find(&solutions)for _, solution := range solutions {listOfAsnmtIDs = append(listOfAsnmtIDs, solution.AssignmentID)}response := database.Table("assignments").Select(`id, created_at, IIF((id IN ?), 'attempted', 'Not attempted') as attempted`, listOfAsnmtIDs).Find(&allAssignments)if response.RowsAffected < 1 {respondToClient(w, 404, nil, "No assignments found")return}//...}
答案1
得分: 0
你只需要列出参数。像这样：
var mad stringfor i, solution := range solutions {mad += strconv.FormatUint(uint64(solution.AssignmentID), 10)if i != len(solutions) {mad += ","}listOfAsnmtIDs = append(listOfAsnmtIDs, solution.AssignmentID)}response := database.Table("assignments").Select(`id, created_at, IIF((id IN ?), 'attempted', 'Not attempted') as attempted`, mad).Find(&allAssignments)
英文:
You just need to list params. Something like this
var mad stringfor i, solution := range solutions {mad += strconv.FormatUint(uint64(solution.AssignmentID), 10)if i != len(solutions) {mad += ","}listOfAsnmtIDs = append(listOfAsnmtIDs, solution.AssignmentID)}response := database.Table("assignments").Select(`id, created_at, IIF((id IN ?), 'attempted', 'Not attempted') as attempted`, mad).Find(&allAssignments)
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