SQL语言系统函数如何获取数据库信息 SQL语言在元数据管理中的实用技巧

SHOW TABLES

information_schema.tables

SELECT name FROM sys.tables

SELECT tablename FROM pg_catalog.pg_tables WHERE schemaname != 'pg_catalog' AND schemaname != 'information_schema'

-- 获取当前数据库的所有表名
SELECT table_name
FROM information_schema.tables
WHERE table_schema = DATABASE();

information_schema.tables

WHERE

table_schema

DATABASE()

DATABASE()

SHOW COLUMNS FROM table_name

information_schema.columns

SELECT column_name, data_type FROM information_schema.columns WHERE table_name = 'your_table_name'

SELECT column_name, data_type FROM information_schema.columns WHERE table_name = 'your_table_name'

-- 获取指定表的列名和数据类型
SELECT column_name, data_type
FROM information_schema.columns
WHERE table_name = 'YourTableName';

YourTableName

column_name

data_type

GRANT

REVOKE

GRANT SELECT, INSERT ON table_name TO user_name

REVOKE SELECT ON table_name FROM user_name

-- 授予用户对表的SELECT权限
GRANT SELECT ON YourTable TO 'YourUser'@'localhost';

-- 撤销用户对表的SELECT权限
REVOKE SELECT ON YourTable FROM 'YourUser'@'localhost';

YourUser

localhost

YourTable

SELECT

FLUSH PRIVILEGES;

mysqldump

pg_dump

mysqldump -u YourUser -pYourPassword YourDatabase > YourDatabase_backup.sql

YourDatabase

YourDatabase_backup.sql

mysql -u YourUser -pYourPassword YourDatabase < YourDatabase_backup.sql

EXPLAIN

EXPLAIN ANALYZE

EXPLAIN

EXPLAIN SELECT * FROM YourTable WHERE YourColumn = 'YourValue';

SELECT

type

possible_keys

key

rows

Extra

type

ALL