From 4c1398846c0548c9e38eebdc00f0845570a4cc61 Mon Sep 17 00:00:00 2001
From: FatttSnake <fatttsnake@gmail.com>
Date: Thu, 9 Jun 2022 12:31:27 +0800
Subject: [PATCH] Add queryCourses()

---
 .../library/database/DatabaseHelper.java      | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java b/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java
index 42cf504..e0956bb 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java
@@ -8,8 +8,12 @@ import com.cfive.classroom.library.database.util.InsertException;
 import com.cfive.classroom.library.database.util.NoConfigException;
 import com.sun.istack.internal.Nullable;
 
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.time.LocalDateTime;
+import java.util.ArrayList;
 import java.util.List;
 
 public class DatabaseHelper {
@@ -253,10 +257,21 @@ public class DatabaseHelper {
         return AttendanceOA.delete(attID);
     }
 
-    public static boolean queryCourses(long tchID) throws NoConfigException, SQLException, DependenciesNotFoundException {
+    public static List<Course> queryCourses(long tchID) throws NoConfigException, SQLException, DependenciesNotFoundException {
         if (isExistsInTeacher(tchID)) throw new DependenciesNotFoundException();
-        // TODO: Query Courses
-        return false;
+        ArrayList<Course> courses = new ArrayList<>();
+        String sql = "SELECT courID FROM course,teacher WHERE course.tchID=teacher.tchID AND course.tchID=?";
+        try (Connection connection = PoolHelper.getConnection()) {
+            try (PreparedStatement preparedStatement = connection.prepareStatement(sql)) {
+                preparedStatement.setLong(1, tchID);
+                try (ResultSet resultSet = preparedStatement.executeQuery()) {
+                    while (resultSet.next()) {
+                        courses.add(selectFromCourse(resultSet.getLong("courID")));
+                    }
+                }
+            }
+        }
+        return courses;
     }
 
     public static void close() {