oracle--查询表的信息 查看备注字段

SELECT A.COLUMN_NAME,   --字段名称
A.DATA_TYPE,     --字段类型
nvl(TO_char(A.DATA_LENGTH), ''),      -- 字段长度
nvl(TO_char(A.DATA_PRECISION), ''),   -- 列相关数据类型(数字类型)的具体长度(有效位数),一个十进制数(NUMBER类型),或一个二进制树(FLOAT类型)
nvl(TO_char(A.DATA_SCALE), '')        -- 小数点位数
FROM SYS.USER_TAB_COLUMNS A
WHERE 1 = 1
AND A.TABLE_NAME = '表名'

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';