Unterschiede

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--- modul:m290:learningunits:lu09:theorie:03 [2024/11/05 13:43] – vdemir
+++ modul:m290:learningunits:lu09:theorie:03 [2024/11/05 14:51] (aktuell) – vdemir
@@ Zeile 53: / Zeile 53: @@
 {{:modul:m290:learningunits:lu09:theorie:crud_r2.png?800|C**R**UD performance in the presentation (POSTMAN) and logic layer (Node Server}}
+==== D - Deletion of one specific record ====
+If we want to delete one specific row of data, we need another method to perform that.
+  app.delete('/user/:id', (req, res) => {
+      const userId = req.params.id;
+      const deleteQuery = 'DELETE FROM users WHERE user_id = ?';
+      db.query(deleteQuery, [userId], (err, result) => {
+          if (err) {
+              res.status(500).send('Error deleting user');
+          } else if (result.affectedRows === 0) {
+              res.status(404).send('User not found');
+          } else {
+              res.send(`User with ID ${userId} deleted successfully`);
+          }
+      });
+  });
+{{:modul:m290:learningunits:lu09:theorie:crud_d.png?800|How to perform a deletion }}
+==== U - Update of one specfic row ====
+Well, if we want to update one row of data, we need the http method PUT.
+  app.put('/user/:id', (req, res) => {
+      const userId = req.params.id;
+      const { username, email } = req.query; // Get username and email from query parameters
+      // Ensure that at least one field is provided
+      if (!username && !email) {
+          return res.status(400).send('At least one field (username or email) must be provided for update.');
+      }
+      // Construct the update query
+      const updateQuery = 'UPDATE users SET username = ?, email = ? WHERE user_id = ?';
+      const values = [username || null, email || null, userId]; // Use null for any field not provided
+      db.query(updateQuery, values, (err, result) => {
+          if (err) {
+              res.status(500).send('Error updating user');
+          } else if (result.affectedRows === 0) {
+              res.status(404).send('User not found');
+          } else {
+              res.send(`User with ID ${userId} updated successfully`);
+          }
+      });
+  });
+  {{:modul:m290:learningunits:lu09:theorie:crud_u.png?800| Update of one row of data}}
+==== C - CREATE: Insert a new row into the db ====
+Finally, with the INSERT operation, we complete our CRUD requirements.
+  // insert a row
+  app.post('/user', (req, res) => {
+      const { username, email } = req.query; // Get username and email from query parameters
+      // Ensure that both fields are provided
+      if (!username || !email) {
+          return res.status(400).send('Username and email are required for insertion.');
+      }
+      // Construct the insert query
+      const insertQuery = 'INSERT INTO users (username, email) VALUES (?, ?)';
+      const values = [username, email]; // Use provided fields for insertion
+      db.query(insertQuery, values, (err, result) => {
+          if (err) {
+              console.error('Error inserting user:', err);
+              return res.status(500).send('Error inserting user');
+          }
+         // Respond with the ID of the newly created user
+          res.status(201).send(`User added with ID: ${result.insertId}`);
+      });
+  });
+{{:modul:m290:learningunits:lu09:theorie:crud_c.png?600| How to insert a row into a database table}}
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 [[https://creativecommons.org/licenses/by-nc-sa/4.0/|{{https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png}}]] Volkan Demir