chore(db): Make the query more simpler to read

Signed-off-by: Git'Fellow <[email protected]>

lib/private/DB/Adapter.php

@@ -46,11 +46,10 @@ public function fixupStatement($statement) {
 	/**
 	 * Create an exclusive read+write lock on a table
 	 *
-	 * @param string $tableName
 	 * @throws Exception
 	 * @since 9.1.0
 	 */
-	public function lockTable($tableName) {
+	public function lockTable(string $tableName): void {
 		$this->conn->beginTransaction();
 		$this->conn->executeUpdate('LOCK TABLE `' .$tableName . '` IN EXCLUSIVE MODE');
 	}
@@ -61,7 +60,7 @@ public function lockTable($tableName) {
 	 * @throws Exception
 	 * @since 9.1.0
 	 */
-	public function unlockTable() {
+	public function unlockTable(): void {
 		$this->conn->commit();
 	}
 
@@ -79,13 +78,15 @@ public function unlockTable() {
 	 * @throws Exception
 	 * @deprecated 15.0.0 - use unique index and "try { $db->insert() } catch (UniqueConstraintViolationException $e) {}" instead, because it is more reliable and does not have the risk for deadlocks - see https://github.com/nextcloud/server/pull/12371
 	 */
-	public function insertIfNotExist($table, $input, ?array $compare = null) {
-		if (empty($compare)) {
-			$compare = array_keys($input);
-		}
-		$query = 'INSERT INTO `' .$table . '` (`'
-			. implode('`,`', array_keys($input)) . '`) SELECT '
-			. str_repeat('?,', count($input) - 1).'? ' // Is there a prettier alternative?
+	public function insertIfNotExist(string $table, array $input, ?array $compare = null): int {
+		$compare = $compare ?: array_keys($input);
+
+		// Prepare column names and generate placeholders
+		$columns = '`' . implode('`,`', array_keys($input)) . '`';
+		$placeholders = implode(', ', array_fill(0, count($input), '?'));
+
+		$query = 'INSERT INTO `' . $table . '` (' . $columns . ') '
+			. 'SELECT ' . $placeholders . ' '
 			. 'FROM `' . $table . '` WHERE ';
 
 		$inserts = array_values($input);
@@ -104,10 +105,9 @@ public function insertIfNotExist($table, $input, ?array $compare = null) {
 		try {
 			return $this->conn->executeUpdate($query, $inserts);
 		} catch (UniqueConstraintViolationException $e) {
-			// if this is thrown then a concurrent insert happened between the insert and the sub-select in the insert, that should have avoided it
-			// it's fine to ignore this then
-			//
-			// more discussions about this can be found at https://github.com/nextcloud/server/pull/12315
+			// This exception indicates a concurrent insert happened between
+			// the insert and the sub-select in the insert, which is safe to ignore.
+			// More details: https://github.com/nextcloud/server/pull/12315
 			return 0;
 		}
 	}