Add $cached param to BaseConnection::tableExists()

system/Database/BaseConnection.php

@@ -1405,10 +1405,41 @@ public function listTables(bool $constrainByPrefix = false)
 
     /**
      * Determine if a particular table exists
+     *
+     * @param bool $cached Whether to use data cache
      */
-    public function tableExists(string $tableName): bool
+    public function tableExists(string $tableName, bool $cached = true): bool
     {
-        return in_array($this->protectIdentifiers($tableName, true, false, false), $this->listTables(), true);
+        if ($cached === true) {
+            return in_array($this->protectIdentifiers($tableName, true, false, false), $this->listTables(), true);
+        }
+
+        if (false === ($sql = $this->_listTables(false, $tableName))) {
+            if ($this->DBDebug) {
+                throw new DatabaseException('This feature is not available for the database you are using.');
+            }
+
+            return false;
+        }
+
+        $tableExists = $this->query($sql)->getResultArray() !== [];
+
+        // if cache has been built already
+        if (! empty($this->dataCache['table_names'])) {
+            $key = array_search(
+                strtolower($tableName),
+                array_map('strtolower', $this->dataCache['table_names']),
+                true
+            );
+
+            // table doesn't exist but still in cache - lets reset cache, it can be rebuilt later
+            // OR if table does exist but is not found in cache
+            if (($key !== false && ! $tableExists) || ($key === false && $tableExists)) {
+                $this->resetDataCache();
+            }
+        }
+
+        return $tableExists;
     }
 
     /**
@@ -1575,9 +1606,11 @@ abstract public function insertID();
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
      *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
+     *
      * @return false|string
      */
-    abstract protected function _listTables(bool $constrainByPrefix = false);
+    abstract protected function _listTables(bool $constrainByPrefix = false, ?string $tableName = null);
 
     /**
      * Generates a platform-specific query string so that the column names can be fetched.

system/Database/Forge.php

@@ -498,7 +498,7 @@ public function createTable(string $table, bool $ifNotExists = false, array $att
         }
 
         // If table exists lets stop here
-        if ($ifNotExists === true && $this->db->tableExists($table)) {
+        if ($ifNotExists === true && $this->db->tableExists($table, false)) {
             $this->reset();
 
             return true;

system/Database/MySQLi/Connection.php

@@ -368,11 +368,17 @@ public function escapeLikeStringDirect($str)
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
      * Uses escapeLikeStringDirect().
+     *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
      */
-    protected function _listTables(bool $prefixLimit = false): string
+    protected function _listTables(bool $prefixLimit = false, ?string $tableName = null): string
     {
         $sql = 'SHOW TABLES FROM ' . $this->escapeIdentifiers($this->database);
 
+        if ($tableName !== null) {
+            return $sql . ' LIKE ' . $this->escape($tableName);
+        }
+
         if ($prefixLimit !== false && $this->DBPrefix !== '') {
             return $sql . " LIKE '" . $this->escapeLikeStringDirect($this->DBPrefix) . "%'";
         }

system/Database/OCI8/Connection.php

@@ -242,11 +242,17 @@ public function affectedRows(): int
 
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
+     *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
      */
-    protected function _listTables(bool $prefixLimit = false): string
+    protected function _listTables(bool $prefixLimit = false, ?string $tableName = null): string
     {
         $sql = 'SELECT "TABLE_NAME" FROM "USER_TABLES"';
 
+        if ($tableName !== null) {
+            return $sql . ' WHERE "TABLE_NAME" LIKE ' . $this->escape($tableName);
+        }
+
         if ($prefixLimit !== false && $this->DBPrefix !== '') {
             return $sql . ' WHERE "TABLE_NAME" LIKE \'' . $this->escapeLikeString($this->DBPrefix) . "%' "
                     . sprintf($this->likeEscapeStr, $this->likeEscapeChar);

system/Database/Postgre/Connection.php

@@ -204,11 +204,17 @@ protected function _escapeString(string $str): string
 
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
+     *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
      */
-    protected function _listTables(bool $prefixLimit = false): string
+    protected function _listTables(bool $prefixLimit = false, ?string $tableName = null): string
     {
         $sql = 'SELECT "table_name" FROM "information_schema"."tables" WHERE "table_schema" = \'' . $this->schema . "'";
 
+        if ($tableName !== null) {
+            return $sql . ' AND "table_name" LIKE ' . $this->escape($tableName);
+        }
+
         if ($prefixLimit !== false && $this->DBPrefix !== '') {
             return $sql . ' AND "table_name" LIKE \''
                 . $this->escapeLikeString($this->DBPrefix) . "%' "

system/Database/SQLSRV/Connection.php

@@ -183,14 +183,20 @@ public function insertID(): int
 
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
+     *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
      */
-    protected function _listTables(bool $prefixLimit = false): string
+    protected function _listTables(bool $prefixLimit = false, ?string $tableName = null): string
     {
         $sql = 'SELECT [TABLE_NAME] AS "name"'
             . ' FROM [INFORMATION_SCHEMA].[TABLES] '
             . ' WHERE '
             . " [TABLE_SCHEMA] = '" . $this->schema . "'    ";
 
+        if ($tableName !== null) {
+            return $sql .= ' AND [TABLE_NAME] LIKE ' . $this->escape($tableName);
+        }
+
         if ($prefixLimit === true && $this->DBPrefix !== '') {
             $sql .= " AND [TABLE_NAME] LIKE '" . $this->escapeLikeString($this->DBPrefix) . "%' "
                 . sprintf($this->likeEscapeStr, $this->likeEscapeChar);

system/Database/SQLite3/Connection.php

@@ -160,9 +160,17 @@ protected function _escapeString(string $str): string
 
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
+     *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
      */
-    protected function _listTables(bool $prefixLimit = false): string
+    protected function _listTables(bool $prefixLimit = false, ?string $tableName = null): string
     {
+        if ($tableName !== null) {
+            return 'SELECT "NAME" FROM "SQLITE_MASTER" WHERE "TYPE" = \'table\''
+                   . ' AND "NAME" NOT LIKE \'sqlite!_%\' ESCAPE \'!\''
+                   . ' AND "NAME" LIKE ' . $this->escape($tableName);
+        }
+
         return 'SELECT "NAME" FROM "SQLITE_MASTER" WHERE "TYPE" = \'table\''
                . ' AND "NAME" NOT LIKE \'sqlite!_%\' ESCAPE \'!\''
                . (($prefixLimit !== false && $this->DBPrefix !== '')

system/Test/Mock/MockConnection.php

@@ -179,8 +179,10 @@ public function insertID(): int
 
     /**
      * Generates the SQL for listing tables in a platform-dependent manner.
+     *
+     * @param string|null $tableName If $tableName is provided will return only this table if exists.
      */
-    protected function _listTables(bool $constrainByPrefix = false): string
+    protected function _listTables(bool $constrainByPrefix = false, ?string $tableName = null): string
     {
         return '';
     }

tests/system/Database/Forge/CreateTableTest.php

@@ -21,26 +21,6 @@
  */
 final class CreateTableTest extends CIUnitTestCase
 {
-    public function testCreateTableWithExists()
-    {
-        $dbMock = $this->getMockBuilder(MockConnection::class)
-            ->setConstructorArgs([[]])
-            ->onlyMethods(['listTables'])
-            ->getMock();
-        $dbMock
-            ->method('listTables')
-            ->willReturn(['foo']);
-
-        $forge                          = new class ($dbMock) extends Forge {
-            protected $createTableIfStr = false;
-        };
-
-        $forge->addField('id');
-        $actual = $forge->createTable('foo', true);
-
-        $this->assertTrue($actual);
-    }
-
     public function testCreateTableWithDefaultRawSql()
     {
         $sql = <<<'SQL'

tests/system/Database/Live/ForgeTest.php

@@ -155,6 +155,55 @@ public function testCreateTable()
         $this->forge->dropTable('forge_test_table', true);
     }
 
+    public function testCreateTableWithExists()
+    {
+        // create table so that it exists in database
+        $this->forge->addField([
+            'id'   => ['type' => 'INTEGER', 'constraint' => 3, 'auto_increment' => true],
+            'name' => ['type' => 'VARCHAR', 'constraint' => 80],
+        ])->addKey('id', true)->createTable('test_exists', true);
+
+        // table exists in cache
+        $this->assertTrue($this->forge->getConnection()->tableExists('db_test_exists', true));
+
+        // table exists without cached results
+        $this->assertTrue($this->forge->getConnection()->tableExists('db_test_exists', false));
+
+        // try creating table when table exists
+        $result = $this->forge->addField([
+            'id'   => ['type' => 'INTEGER', 'constraint' => 3, 'auto_increment' => true],
+            'name' => ['type' => 'VARCHAR', 'constraint' => 80],
+        ])->addKey('id', true)->createTable('test_exists', true);
+
+        $this->assertTrue($result);
+
+        // Delete table outside of forge. This should leave table in cache as existing.
+        $this->forge->getConnection()->query('DROP TABLE ' . $this->forge->getConnection()->protectIdentifiers('db_test_exists', true, null, false));
+
+        // table stil exists in cache
+        $this->assertTrue($this->forge->getConnection()->tableExists('db_test_exists', true));
+
+        // table does not exist without cached results - this will update the cache
+        $this->assertFalse($this->forge->getConnection()->tableExists('db_test_exists', false));
+
+        // the call above should update the cache - table should not exist in cache anymore
+        $this->assertFalse($this->forge->getConnection()->tableExists('db_test_exists', true));
+
+        // try creating table when table does not exist but still in cache
+        $result = $this->forge->addField([
+            'id'   => ['type' => 'INTEGER', 'constraint' => 3, 'auto_increment' => true],
+            'name' => ['type' => 'VARCHAR', 'constraint' => 80],
+        ])->addKey('id', true)->createTable('test_exists', true);
+
+        $this->assertTrue($result);
+
+        // check that the table does now exist without cached results
+        $this->assertTrue($this->forge->getConnection()->tableExists('db_test_exists', false));
+
+        // drop table so that it doesn't mess up other tests
+        $this->forge->dropTable('test_exists');
+    }
+
     public function testCreateTableApplyBigInt()
     {
         $this->forge->dropTable('forge_test_table', true);

user_guide_src/source/changelogs/v4.2.5.rst

@@ -12,7 +12,8 @@ Release Date: Unreleased
 BREAKING
 ********
 
-none.
+- The method signature of ``BaseConnection::tableExists()`` has been changed. A second optional parameter ``$cached`` was added. This directs whether to use cache data or not. Default is ``true``, use cache data.
+- The abstract method signature of ``BaseBuilder::_listTables()`` has been changed. A second optional parameter ``$tableName`` was added. Providing a table name will generate SQL listing only that table.
 
 Enhancements
 ************