DESCRIBE Statements

DESCRIBE statements are used to describe the schema of a table or a view.

Run a DESCRIBE statement

Java

DESCRIBE statements can be executed with the executeSql() method of the TableEnvironment. The executeSql() method returns the schema of given table for a successful DESCRIBE operation, otherwise will throw an exception.

The following examples show how to run a DESCRIBE statement in TableEnvironment.

Scala

DESCRIBE statements can be executed with the executeSql() method of the TableEnvironment. The executeSql() method returns the schema of given table for a successful DESCRIBE operation, otherwise will throw an exception.

The following examples show how to run a DESCRIBE statement in TableEnvironment.

Python

DESCRIBE statements can be executed with the execute_sql() method of the TableEnvironment. The execute_sql() method returns the schema of given table for a successful DESCRIBE operation, otherwise will throw an exception.

The following examples show how to run a DESCRIBE statement in TableEnvironment.

SQL CLI

DESCRIBE statements can be executed in SQL CLI.

The following examples show how to run a DESCRIBE statement in SQL CLI.

Java

  1. TableEnvironment tableEnv = TableEnvironment.create(...);
  3. // register a table named "Orders"
  4. tableEnv.executeSql(
  5.         "CREATE TABLE Orders (" +
  6.         " `user` BIGINT NOT NULl," +
  7.         " product VARCHAR(32)," +
  8.         " amount INT," +
  9.         " ts TIMESTAMP(3)," +
  10.         " ptime AS PROCTIME()," +
  11.         " PRIMARY KEY(`user`) NOT ENFORCED," +
  12.         " WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS" +
  13.         ") with (...)");
  15. // print the schema
  16. tableEnv.executeSql("DESCRIBE Orders").print();
  18. // print the schema
  19. tableEnv.executeSql("DESC Orders").print();

Scala

  1. val tableEnv = TableEnvironment.create(...)
  3. // register a table named "Orders"
  4.  tableEnv.executeSql(
  5.         "CREATE TABLE Orders (" +
  6.         " `user` BIGINT NOT NULl," +
  7.         " product VARCHAR(32)," +
  8.         " amount INT," +
  9.         " ts TIMESTAMP(3)," +
  10.         " ptime AS PROCTIME()," +
  11.         " PRIMARY KEY(`user`) NOT ENFORCED," +
  12.         " WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS" +
  13.         ") with (...)")
  15. // print the schema
  16. tableEnv.executeSql("DESCRIBE Orders").print()
  18. // print the schema
  19. tableEnv.executeSql("DESC Orders").print()

Python

  1. table_env = TableEnvironment.create(...)
  3. # register a table named "Orders"
  4. table_env.execute_sql( \
  5.         "CREATE TABLE Orders (" 
  6.         " `user` BIGINT NOT NULl," 
  7.         " product VARCHAR(32),"
  8.         " amount INT,"
  9.         " ts TIMESTAMP(3),"
  10.         " ptime AS PROCTIME(),"
  11.         " PRIMARY KEY(`user`) NOT ENFORCED,"
  12.         " WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS"
  13.         ") with (...)");
  15. # print the schema
  16. table_env.execute_sql("DESCRIBE Orders").print()
  18. # print the schema
  19. table_env.execute_sql("DESC Orders").print()

SQL CLI

  1. Flink SQL> CREATE TABLE Orders (
  2. >  `user` BIGINT NOT NULl,
  3. >  product VARCHAR(32),
  4. >  amount INT,
  5. >  ts TIMESTAMP(3),
  6. >  ptime AS PROCTIME(),
  7. >  PRIMARY KEY(`user`) NOT ENFORCED,
  8. >  WATERMARK FOR ts AS ts - INTERVAL '1' SECONDS
  9. > ) with (
  10. >  ...
  11. > );
  12. [INFO] Table has been created.
  14. Flink SQL> DESCRIBE Orders;
  16. Flink SQL> DESC Orders;

The result of the above example is:

Java

  2. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  3. |    name |                             type |  null |       key | computed column |                  watermark |
  4. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  5. |    user |                           BIGINT | false | PRI(user) |                 |                            |
  6. | product |                      VARCHAR(32) |  true |           |                 |                            |
  7. |  amount |                              INT |  true |           |                 |                            |
  8. |      ts |           TIMESTAMP(3) *ROWTIME* |  true |           |                 | `ts` - INTERVAL '1' SECOND |
  9. |   ptime | TIMESTAMP(3) NOT NULL *PROCTIME* | false |           |      PROCTIME() |                            |
  10. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  11. 5 rows in set

Scala

  2. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  3. |    name |                             type |  null |       key | computed column |                  watermark |
  4. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  5. |    user |                           BIGINT | false | PRI(user) |                 |                            |
  6. | product |                      VARCHAR(32) |  true |           |                 |                            |
  7. |  amount |                              INT |  true |           |                 |                            |
  8. |      ts |           TIMESTAMP(3) *ROWTIME* |  true |           |                 | `ts` - INTERVAL '1' SECOND |
  9. |   ptime | TIMESTAMP(3) NOT NULL *PROCTIME* | false |           |      PROCTIME() |                            |
  10. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  11. 5 rows in set

Python

  2. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  3. |    name |                             type |  null |       key | computed column |                  watermark |
  4. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  5. |    user |                           BIGINT | false | PRI(user) |                 |                            |
  6. | product |                      VARCHAR(32) |  true |           |                 |                            |
  7. |  amount |                              INT |  true |           |                 |                            |
  8. |      ts |           TIMESTAMP(3) *ROWTIME* |  true |           |                 | `ts` - INTERVAL '1' SECOND |
  9. |   ptime | TIMESTAMP(3) NOT NULL *PROCTIME* | false |           |      PROCTIME() |                            |
  10. +---------+----------------------------------+-------+-----------+-----------------+----------------------------+
  11. 5 rows in set

SQL CLI

  2. root
  3.  |-- user: BIGINT NOT NULL
  4.  |-- product: VARCHAR(32)
  5.  |-- amount: INT
  6.  |-- ts: TIMESTAMP(3) *ROWTIME*
  7.  |-- ptime: TIMESTAMP(3) NOT NULL *PROCTIME* AS PROCTIME()
  8.  |-- WATERMARK FOR ts AS `ts` - INTERVAL '1' SECOND
  9.  |-- CONSTRAINT PK_3599338 PRIMARY KEY (user)

Syntax

  1. { DESCRIBE | DESC } [catalog_name.][db_name.]table_name