How to query the primary key table in oracle

In Oracle database, the primary key of a table is an important database entity constraint, which is usually used to ensure the integrity and uniqueness of data. When we need to query a table with a primary key, there are several ways to do it.

Method 1: By querying the table structure information

We can query the system view or table structure information to obtain the primary key information of the table. The following are some commonly used query statements:

1. The primary key name of the query table

SELECT constraint_name
FROM user_constraints
WHERE table_name = 'table_name'
AND constraint_type = 'P';

Among them, user_constraints is the system view, used to query all constraint information under the current user; table_name is the name of the target table; 'P' represents the primary key constraint.

2. Query all primary key column names of the table

SELECT column_name
FROM user_cons_columns
WHERE table_name = 'table_name'
AND constraint_name = 'constraint_name';

This query statement uses the user_cons_columns system view to query the primary key column names of the target table. Among them, constraint_name is the name of the primary key constraint queried previously.

Method 2: Use Oracle Enterprise Manager

Oracle Enterprise Manager is an Oracle database management tool. It provides an intuitive user interface that can easily query primary key tables.

1. Open Oracle Enterprise Manager
2. Click the "Database" tab and select the target database instance
3. Click the "Schema" tab and find the target table
4. Click the table name to view the primary key information

Under the table, we can see the primary key column, primary key name and other information of the table.

Method 3: Using PL/SQL

We can also use PL/SQL development tools or other database management tools to query the primary key table. The following is an example stored procedure for querying the primary key table:

CREATE OR REPLACE PROCEDURE show_pk_tables
IS
  v_table_name VARCHAR2(30);
  v_pk_name VARCHAR2(30);
BEGIN
  FOR c IN (SELECT table_name FROM user_tables)
  LOOP
    BEGIN
      SELECT constraint_name INTO v_pk_name
      FROM user_constraints
      WHERE table_name = c.table_name
      AND constraint_type = 'P';

      DBMS_OUTPUT.PUT_LINE('Table Name: ' || c.table_name || ', Primary Key: ' || v_pk_name);
    END;
  END LOOP;
END;

This stored procedure will traverse all tables under the current user, query their primary key information, and finally print out the results.

To sum up, we can use query table structure information, Oracle Enterprise Manager, PL/SQL and other methods to query the primary key table. Which method to choose depends on personal habits and actual application scenarios. No matter which method is used, it can meet the query needs and help us better manage the Oracle database.

The above is the detailed content of How to query the primary key table in oracle. For more information, please follow other related articles on the PHP Chinese website!