MySQL的 information_schema 數據庫，保存著數據庫的容量和使用信息。可查詢數據庫中每個表占用的空間、表記錄的行數。
Tables表的結構
CREATE TEMPORARY TABLE `TABLES` (
`TABLE_CATALOG` varchar(512) NOT NULL DEFAULT '',
`TABLE_SCHEMA` varchar(64) NOT NULL DEFAULT '',
`TABLE_NAME` varchar(64) NOT NULL DEFAULT '',
`TABLE_TYPE` varchar(64) NOT NULL DEFAULT '',
`ENGINE` varchar(64) DEFAULT NULL,
`VERSION` bigint(21) unsigned DEFAULT NULL,
`ROW_FORMAT` varchar(20) DEFAULT NULL,
`TABLE_ROWS` bigint(21) unsigned DEFAULT NULL,
`AVG_ROW_LENGTH` bigint(21) unsigned DEFAULT NULL,
`DATA_LENGTH` bigint(21) unsigned DEFAULT NULL,
`MAX_DATA_LENGTH` bigint(21) unsigned DEFAULT NULL,
`INDEX_LENGTH` bigint(21) unsigned DEFAULT NULL,
`DATA_FREE` bigint(21) unsigned DEFAULT NULL,
`AUTO_INCREMENT` bigint(21) unsigned DEFAULT NULL,
`CREATE_TIME` datetime DEFAULT NULL,
`UPDATE_TIME` datetime DEFAULT NULL,
`CHECK_TIME` datetime DEFAULT NULL,
`TABLE_COLLATION` varchar(32) DEFAULT NULL,
`CHECKSUM` bigint(21) unsigned DEFAULT NULL,
`CREATE_OPTIONS` varchar(255) DEFAULT NULL,
`TABLE_COMMENT` varchar(2048) NOT NULL DEFAULT ''
) ENGINE=MEMORY DEFAULT CHARSET=utf8;
- 主要字段說明
TABLE_SCHEMA : 數據庫名
TABLE_NAME：表名
ENGINE：所使用的存儲引擎
TABLE_ROWS：記錄數
DATA_LENGTH：數據大小
INDEX_LENGTH：索引大小
實例
查詢指定數據庫的所有表名稱，行數
USE information_schema;
SELECT TABLE_NAME,table_rows FROM TABLES WHERE TABLE_SCHEMA = '數據庫名字' ORDER BY table_rows DESC;
- 查詢指定庫的數據大小，索引大小
SELECT CONCAT(ROUND(SUM(DATA_LENGTH/1024/1024),2),'MB') AS total_data_size, CONCAT(ROUND(SUM(index_length)/(1024*1024), 2), ' MB') AS total_index_size FROM TABLES WHERE table_schema = '數據庫名字';
