Question

如何使用sql语句，查询oracle的表注释等信息？

select comments
from USER_COL_COMMENTS
where table_name= 'student'
and column_name= 'stunum'

Answer 1

Oracle 下读取表/字段的备注信息
Oracle 通过COMMENT ON TABLE / COMMENT ON COLUMN 追加表/字段的备注。

CREATE TABLE "MR_DEPT" (
"DEPT_ID" NUMBER NOT NULL ,
"PARENT_ID" NUMBER,
"DEPT_NAME" CHAR(20) NOT NULL ,
"STATUS" NUMBER DEFAULT 1 NOT NULL ,
PRIMARY KEY ("DEPT_ID")
);

COMMENT ON TABLE "MR_DEPT" IS '部门表';
COMMENT ON COLUMN "MR_DEPT"."DEPT_ID" IS '部门编号';
COMMENT ON COLUMN "MR_DEPT"."PARENT_ID" IS '上级部门编号';
COMMENT ON COLUMN "MR_DEPT"."DEPT_NAME" IS '部门名';
COMMENT ON COLUMN "MR_DEPT"."STATUS" IS '状态';

备注加好以后，如何在查询中检索呢？

查询表的备注信息
SELECT
TABLE_NAME,
TABLE_TYPE,
COMMENTS
FROM
USER_TAB_COMMENTS
WHERE
TABLE_NAME = 'MR_DEPT;

查询字段的备注信息

SELECT
TABLE_NAME,
COLUMN_NAME,
COMMENTS
FROM
USER_COL_COMMENTS
WHERE
TABLE_NAME = 'MR_DEPT;

Answer 2

看看了网上的好多的sql查询语句，但是感觉那些都很简单，有谁能给我些高级这是我做过的几个SQL面试题，我写好了表并添加了测试数据,有兴趣的话试一

Answer 3

SELECT
a.table_name,
a.column_name,
a.data_type,
CASE WHEN a.data_precision is null THEN a.data_length ||'' else a.data_precision||','||a.data_scale END data_precision_scale,
a.column_id,b.comments
FROM all_tab_columns a,all_col_comments b
WHERE a.owner=b.owner
AND a.table_name=b.table_name
AND a.column_name=b.column_name
AND lower(a.table_name) = ''student'

Answer 4

你就直接执行这个即可
select * from user_tab_comments;

Answer 5

USER_TAB_COMMENTS