docs: replace type mixed at Database connection.

Author: ping-yee

system/Database/BaseConnection.php

@@ -456,7 +456,7 @@ abstract protected function _close();
     /**
      * Create a persistent database connection.
      *
-     * @return mixed
+     * @return false|object|resource
      */
     public function persistentConnect()
     {
@@ -558,7 +558,7 @@ abstract protected function execute(string $sql);
      * Should automatically handle different connections for read/write
      * queries if needed.
      *
-     * @param mixed ...$binds
+     * @param array|string|null ...$binds
      *
      * @return BaseResult|bool|Query BaseResult when “read” type query, bool when “write” type query, Query when prepared query
      * @phpstan-return BaseResult<TConnection, TResult>|bool|Query
@@ -1747,7 +1747,7 @@ protected function _enableForeignKeyChecks()
     /**
      * Accessor for properties if they exist.
      *
-     * @return mixed
+     * @return array|bool|float|int|object|resource|string|null
      */
     public function __get(string $key)
     {

system/Database/ConnectionInterface.php

@@ -12,6 +12,8 @@
 namespace CodeIgniter\Database;
 
 /**
+ * @property Query $lastQuery
+ *
  * @template TConnection of object|resource
  * @template TResult of object|resource
  */
@@ -62,7 +64,7 @@ public function getConnection(?string $alias = null);
     /**
      * Select a specific database table to use.
      *
-     * @return mixed
+     * @return bool
      */
     public function setDatabase(string $databaseName);
 
@@ -98,7 +100,7 @@ public function getVersion(): string;
      * Should automatically handle different connections for read/write
      * queries if needed.
      *
-     * @param mixed ...$binds
+     * @param array|string|null ...$binds
      *
      * @return BaseResult|bool|Query
      * @phpstan-return BaseResult<TConnection, TResult>|bool|Query
@@ -127,7 +129,7 @@ public function table($tableName);
     /**
      * Returns the last query's statement object.
      *
-     * @return mixed
+     * @return Query
      */
     public function getLastQuery();
 
@@ -150,7 +152,7 @@ public function escape($str);
      *
      * @param array ...$params
      *
-     * @return mixed
+     * @return array|bool|float|int|object|resource|string|null
      */
     public function callFunction(string $functionName, ...$params);
 

system/Database/Postgre/Connection.php

@@ -533,7 +533,7 @@ protected function _transRollback(): bool
      *
      * Overrides BaseConnection::isWriteType, adding additional read query types.
      *
-     * @param mixed $sql
+     * @param string $sql
      */
     public function isWriteType($sql): bool
     {

system/Database/SQLSRV/Connection.php

@@ -44,7 +44,7 @@ class Connection extends BaseConnection
      * FALSE or SQLSRV_CURSOR_FORWARD would increase performance,
      * but would disable num_rows() (and possibly insert_id())
      *
-     * @var mixed
+     * @var bool|string
      */
     public $scrollable;
 
@@ -436,7 +436,7 @@ public function affectedRows(): int
     /**
      * Select a specific database table to use.
      *
-     * @return mixed
+     * @return bool
      */
     public function setDatabase(?string $databaseName = null)
     {
@@ -485,7 +485,7 @@ protected function execute(string $sql)
     /**
      * Returns the last error encountered by this connection.
      *
-     * @return mixed
+     * @return array<string, int|string>
      *
      * @deprecated Use `error()` instead.
      */
@@ -546,7 +546,7 @@ public function getVersion(): string
      *
      * Overrides BaseConnection::isWriteType, adding additional read query types.
      *
-     * @param mixed $sql
+     * @param string $sql
      */
     public function isWriteType($sql): bool
     {