[英]How to get column names of a hypothetical table returned by a query oracle sql
Suppose I have a complicated SQL query like 假设我有一个复杂的SQL查询,例如
select *
from mydbadmin.tablename
inner join mydbadmin.othertablename
on mydbadmin.tablename.id = mydbadmin.othertablename.id
where mydbadmin.tablename.y = 2
What query can I make to get the headers of the table running this query would return? 我可以进行什么查询来获取运行该查询的表的标题?
Notes: 笔记:
I've checked Oracle query to fetch column names , but that doesn't seem to help because I'm not trying to find the names from an existing table*. 我已经检查了Oracle查询以获取列名 ,但这似乎无济于事,因为我没有尝试从现有表中查找名称*。
*I have no ability to actually create this table, so making it and then running the ordinary query isn't an option. *我实际上无法创建此表,因此使其无法选择然后再运行普通查询是不可行的。
You may use the DESCRIBE_COLUMNS Procedure of the DBMS_SQL package 您可以使用DBMS_SQL程序包的DESCRIBE_COLUMNS过程
Here are the critical steps: open cursor, parse it and execute. 这是关键步骤:打开游标,解析并执行。 Finaly call the
describe_columns
, which returns the definition in DBMS_SQL.DESC_TAB
最后调用
describe_columns
,它返回DBMS_SQL.DESC_TAB
的定义
c := DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE(c, q'[SELECT 'x' col1, sysdate col2, 1 col3 FROM dual]', DBMS_SQL.NATIVE);
d := DBMS_SQL.EXECUTE(c);
DBMS_SQL.DESCRIBE_COLUMNS(c, col_cnt, rec_tab);
The sample output for the first column of the above query is 上面查询的第一列的示例输出是
col_type = 96
col_maxlen = 1
col_name = COL1
col_name_len = 4
col_schema_name =
col_schema_name_len = 0
col_precision = 0
col_scale = 0
col_null_ok = true
The full example see in Oracle Documentation 完整示例参见Oracle文档
As an alternative you may use JDBC resultSet.getMetaData()
method. 或者,您可以使用JDBC
resultSet.getMetaData()
方法。
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