Test existence of row field

@param  string  $columnName   The column key.
@return boolean
490681
public function __isset($columnName)
    {
        $columnName = $this->_transformColumn($columnName);
        return array_key_exists($columnName, $this->_data);
    }
831162
protected function get_select_search_in_column($columnname) {
        global $DB;

        if ($DB->sql_regex_supported()) {
            // Database supports regex, use it for better match.
            $select = $columnname . ' ' . $DB->sql_regex() . ' ?';
            $params = ["(src|data)\ *=\ *[\\\"\']http://"];
        } else {
            // Databases without regex support should use case-insensitive LIKE.
            // This will have false positive matches and more results than we need, we'll have to filter them in php.
            $select = $DB->sql_like($columnname, '?', false);
            $params = ['%=%http://%'];
        }

        return [$select, $params];
    }
892513
public static function tableExists($tableName)
    {
        $query = "SELECT 1 FROM $tableName LIMIT 1";

        try {
            $result = Connection::db()->query($query);
        } catch (Exception $e) {
            return false;
        }

        return $result !== false;
    }
231425
public function isCustomColumn($columnName)
    {
        $columnName = str_replace('.', '_', $columnName);
        $methodName = camel_case('laratables_custom_'.$columnName);

        if (method_exists($this->class, $methodName)) {
            return $methodName;
        }

        return false;
    }
653637
public function hasField($tableName, $fieldName)
    {
        if (!$this->hasTable($tableName)) {
            return false;
        }
        $fields = $this->fieldList($tableName);
        return array_key_exists($fieldName, $fields);
    }
175968
public function tableExists($tablename)
  {
    $fromdb = "";

    if ($pos = strpos($tablename, "."))
    {
      $fromdb = "from `".substr($tablename, 0, $pos)."`";
      $tablename = substr($tablename, $pos+1);
    }

    $query = "show tables $fromdb like ".$this->quote($tablename);
    $result = $this->q($query);

    $exists = mysqli_num_rows($result) != 0;
    mysqli_free_result($result);
    return $exists;
  }
1250670
public function existTable(string $tableName): bool
    {
        [$dbName, $tableName] = $this->parseTableName($tableName);

        $sql = 'SELECT table_name
            FROM information_schema.tables
            WHERE table_schema = %s
            AND table_name = %s;';

        $sql = sprintf($sql, $dbName, $tableName);
        $row = $this->db->query($sql)->fetch(PDO::FETCH_ASSOC);

        return isset($row['table_name']);
    }
723609
protected function tableExists($tableName)
    {
        $found    = false;
        $iterator = $this->dynamoDb->getClient()->getIterator('ListTables');
        foreach ($iterator as $table) {
            if ($table === $tableName) {
                $found = true;
            }
        }

        return $found;
    }
335456
public function getColumnType($tableName, $columnName) {
        $columns = $this->getTableColumns($tableName);
        foreach ($columns as $column) {
            if ($column['Field'] != $columnName)
                continue;
            $type = explode('(', $column['Type'], 2);
            return $type[0];
        }
        throw new \Exception("Column `$columnName` not found in table `$tableName`!");
    }
341505
public function columnsAreIndexed(array $columnNames)
    {
        foreach ($this->getIndexes() as $index) {
            /** @var $index Index */
            if ($index->spansColumns($columnNames)) {
                return true;
            }
        }

        return false;
    }
1211389
function field($fieldName) {
        if ($fieldName) {
            if ($this->fields && $this->fields != '*') {
                if ($fieldName == 'SQL_CALC_FOUND_ROWS *') {
                    $this->fields = 'SQL_CALC_FOUND_ROWS' . " $this->fields";
                }
                else if ($fieldName != '*') {
                    $this->fields = $fieldName . ",$this->fields";
                }
                //else {
                //    $this->fields .= ',' . $fieldName;
                //}
            }
            else {
                $this->fields = $fieldName;
            }
        }
        return $this;
    }
450124
public function hasColumn($col, $caseInsensitive = false)
    {
        if ($col instanceof Column) {
            $col = $col->getName();
        }
        if ($caseInsensitive) {
            return array_key_exists(strtolower($col), $this->columnsByLowercaseName);
        } else {
            return array_key_exists($col, $this->columnsByName);
        }
    }
297365
protected function tableExists($tableName)
    {
        $tables = $this->connection->getSchemaManager()->listTables();

        foreach ($tables as $table) {
            if ($table->getName() == $tableName) {
                return true;
            }
        }

        return false;
    }
754406
public function getFieldInformation($tableName, $fieldName)
    {
        $columns = $this->database->metaColumns($tableName);

        foreach($columns as $column) {
            if ($column->name === $fieldName) {

                return $column;
            }
        }

        return null;
    }
1321389
private function getField($fieldname)
    {
        if (array_key_exists($fieldname, $this->colmodel)) {
            return $this->colmodel[$fieldname];
        } else {
            return false;
        }
    }
515833
public function getColumn($columnName)
    {
        $columnName = $this->normalizeIdentifier($columnName);
        if (! $this->hasColumn($columnName)) {
            throw SchemaException::columnDoesNotExist($columnName, $this->_name);
        }

        return $this->_columns[$columnName];
    }
117560
function columnExists($fieldname, $source)
    {
        if ( is_string($source) ) {  // Demand table exists
            $source = self::describe($source);
            if ( ! $source ) throw new \Exception("Could not find $source");
        }
        $column = self::describeColumn($fieldname, $source);
        return is_array($column);
    }