ORACLE中查询当前用户下的所有表，某个表的表结构

SELECT
	table_name 
FROM
	user_tables 
WHERE
	TABLESPACE_NAME = 'PROD_ENTITY' 
	AND USER = 'PROD_ENTITY' 
	AND TABLE_NAME NOT LIKE '%UDIC_%'

查看某个表的表结构，包括字段名称，字段类型，字段长度，是否为空，是否主键

SELECT
	c.*,
	d.comments column_comment 
FROM
	(
	SELECT
		a.column_name,
		a.data_type || '(' || data_length || ')' column_type,
		a.nullable is_nullable,
	CASE
			
			WHEN b.column_name IS NOT NULL THEN
			'PK' ELSE '' 
		END column_key 
FROM
	user_tab_columns a
	LEFT JOIN ( SELECT cu.* FROM user_cons_columns cu, user_constraints au WHERE cu.constraint_name = au.constraint_name AND au.constraint_type = 'P' ) b ON b.table_name = a.Table_Name 
	AND a.column_name = b.column_name 
WHERE
	a.Table_Name = 'META_FIELD' 
	) c
	LEFT JOIN user_col_comments d ON c.column_name = d.column_name 
WHERE
	d.table_name = 'META_FIELD'

加载某个库的所有表已经所有表的所有字段，类型，长度，注释等

SELECT
	c.TABLE_NAME  ,
	t.COMMENTS TABLE_COMMENTS,
	cc.COLUMN_NAME ,
	cc.COMMENTS COLUMN_COMMENTS ,
	c.DATA_TYPE,
	c.DATA_LENGTH ,
	c.DATA_SCALE,
	c.NULLABLE 
FROM
	dba_tab_columns c
	LEFT JOIN dba_col_comments cc ON c.table_name = cc.table_name 
	AND c.column_name = cc.column_name
	LEFT JOIN dba_tab_comments t ON c.table_name = t.table_name 
WHERE
	c.OWNER = 'PROD_ENTITY_ZGND' 
	-- BIN 开头的表是已经删除了的表，oracle中存在类似于回收站的东西，删除了的表就放在其中 --
	AND c.table_name NOT LIKE 'BIN$%==$0' 
ORDER BY
	c.table_name;