How can you query columns and their data types in Oracle?
You can use the `DESCRIBE` command or query system tables in Oracle to view the columns and their data types of a table.
Option 1: Utilize the `DESCRIBE` command.
DESCRIBE 表名;
For example, to view the columns and data types of a table named ’employees’, you can perform the following action:
DESCRIBE employees;
Option 1: Method 2: Refer to the system table.
In Oracle, table metadata is stored and can be retrieved by querying system tables such as `ALL_TAB_COLUMNS` or `USER_TAB_COLUMNS` to get detailed information about columns, such as column names and data types.
SELECT COLUMN_NAME, DATA_TYPEFROM ALL_TAB_COLUMNS
WHERE TABLE_NAME = '表名';
`ALL_TAB_COLUMNS` and `USER_TAB_COLUMNS` tables store information of tables under different users. Choose the appropriate table based on the user’s permissions by replacing `’table name’` with the actual table name.
For example, to inquire about the columns and data types of the `employees` table, you can perform the following action:
SELECT COLUMN_NAME, DATA_TYPEFROM ALL_TAB_COLUMNS
WHERE TABLE_NAME = 'employees';
The above are some common methods to query the columns and their data types of tables in an Oracle database. The specific method to use depends on your needs and access permissions.
