Oracle obtains table structure information: Table Name, view or not, field name, type, length, non-empty, primary key, and oracle View

Oracle obtains table structure information: Table Name, view or not, field name, type, length, non-empty, primary key, and oracle View

select       a.TABLE_NAME as "TableName",       case when (select count(*) from user_views v where v.VIEW_NAME =a.TABLE_NAME )>0 then 'V' else 'U'end as "TableType",       a.COLUMN_NAME as "ColumnName",       A.COLUMN_ID as "ColumnIndex",       a.DATA_TYPE as "DataType",       case           when a.DATA_TYPE = 'NUMBER' then           case when a.Data_Precision is null then             a.Data_Length             else                a.Data_Precision               end          else          a.Data_Length       end as "Length",       case when a.nullable = 'N' then  '0' else '1' end as "IsNullable",       b.comments as "Description",        case          when (select count(*) from user_cons_columns c             where c.table_name=a.TABLE_NAME and c.column_name=a.COLUMN_NAME and c.constraint_name=                (select d.constraint_name from user_constraints d where d.table_name=c.table_name and d.constraint_type   ='P')                 )>0 then '1' else '0'end as "IsPK"              from USER_TAB_COLS a,       sys.user_col_comments b where a.table_name = b.table_name             and b.COLUMN_NAME = a.COLUMN_NAME              order by a.TABLE_NAME, a.COLUMN_ID

Query all the field names in the table with known table names in oracle. Check whether each field is a primary key, a foreign key, or an empty SQL statement,

Query all the columns and their attributes of a table:
Select t. *, c. COMMENTS
From user_tab_columns t, user_col_comments c
Where t. table_name = c. table_name and t. column_name = c. column_name and t. table_name = women;
Query the table's primary key:
Select cu .*
From user_cons_columns cu, user_constraints au
Where cu. constraint_name = au. constraint_name and au. constraint_type = 'p' and au. table_name = women;
Search for the table's foreign key (including the name, referenced table name, and corresponding key name. The following is a multi-step query ):
Select * from user_constraints c where c. constraint_type = 'r' and c. table_name = women
Query the names of Columns with foreign key constraints:
Select * from user_cons_columns cl where cl. constraint_name = foreign key name;
Query the column name of the key of the referenced table:
Select * from user_cons_columns cl where cl. constraint_name = foreign key reference table key name;

Obtain basic information about each column in a specified table in oracle

Method 1:
Run the following command in Oracle SQL Plus:
DESC table name;
Method 2:
Use the PLSQL Developer tool, right-click the table name, click Edit, and select columns]
Or enter the DESC table name in the PLSQL Developer command window;