列举模式中的表

Oracle

select table_name from all_tables where owner = 'SCOTT';

MySQL

select table_namefrom information_schema.tableswhere table_schema = 'mysql';

列举字段

Oracle

select column_name, data_type, column_idfrom all_tab_columns
where owner = 'SCOTT' and table_name = 'EMP';

MySQL

select column_name, data_type, ordinal_positionfrom information_schema.columns
where table_schema = 'mysql'and table_name = 'emp';

列举索引列

Oracle

select table_name, index_name, column_name, column_positionfrom sys.all_ind_columns where table_name = 'EMP'and table_owner = 'SCOTT';

MySQL

show index from emp;

列举约束

Oracle

select a.table_name,a.constraint_name,b.column_name,a.constraint_typefrom all_constraints a,all_cons_columns bwhere a.table_name = 'EMP'and a.owner = 'SCOTT'and a.table_name = b.table_nameand a.owner = b.ownerand a.constraint_name = b.constraint_name;

MySQL

select a.table_name,a.constraint_name,b.column_name,a.constraint_typefrom information_schema.table_constraints a,information_schema.key_column_usage bwhere a.table_name = 'emp'and a.table_schema = 'mysql'and a.table_name = b.table_nameand a.table_schema = b.table_schemaand a.constraint_name = b.constraint_name;

列举非索引外键

列出含有非索引外键的表。例如，希望确认emp表的外键是否加入了索引：
Oracle

select a.table_name,a.constraint_name,a.column_name,c.index_namefrom all_cons_columns a,all_constraints b,all_ind_columns cwhere a.table_name = 'EMP'and a.owner = 'SCOTT'and b.constraint_type = 'R'and a.owner = b.ownerand a.table_name = b.table_nameand a.constraint_name = b.constraint_nameand a.owner = c.table_owner(+)and a.table_name = c.table_name (+)and a.column_name = c.column_name (+)and c.index_name is null;

描述Oracle数据字典视图

查询dictionary视图，并列出数据字典视图及其目的：

select table_name, commentsfrom dictionary
order by table_name;

查询dict_columns并找出某个数据字典视图的各列含义：

select column_name, commentsfrom dict_columns
where table_name = 'ALL_TAB_COLUMNS';

《SQL经典实例》第五章