# swoole_table->column 内存表增加一列 ```php bool swoole_table->column(string $name, int $type, int $size = 0); ``` * $name指定字段的名称 * $type指定字段类型，支持3种类型，swoole_table::TYPE_INT, swoole_table::TYPE_FLOAT, swoole_table::TYPE_STRING * $size指定字符串字段的最大长度，单位为字节。字符串类型的字段必须指定$size > swoole_table::TYPE_INT默认为4个字节，可以设置1，2，4，8一共4种长度 > swoole_table::TYPE_STRING设置后，设置的字符串不能超过此长度 > swoole_table::TYPE_FLOAT会占用8个字节的内存 > 非x86环境需要内存对齐 ```php /* Linux raspberrypi 4.4.34-v7+ #930 SMP Wed Nov 23 15:20:41 GMT 2016 armv7l GNU/Linux gcc version 4.9.2 (Raspbian 4.9.2-10) model name : ARMv7 Processor rev 4 (v7l) BogoMIPS : 76.80 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 CPU implementer : 0x41 CPU architecture: 7 CPU variant : 0x0 CPU part : 0xd03 CPU revision : 4 */ //bad use Swoole\Table; $table = new \Swoole\Table(8); $table->column('data',Table::TYPE_STRING, 1); $table->create(); $table->set(1,[]); var_dump($table->get(1)); //result: Bus error //good use Swoole\Table; $table = new \Swoole\Table(8); $table->column('data',Table::TYPE_STRING, 1); $table->column('pad',Table::TYPE_STRING, 1); $table->create(); $table->set(1,[]); var_dump($table->get(1)); /* result array(2) { ["data"]=> string(0) "" ["pad"]=> string(0) "" } */ ```