USE Statements

USE Statements

USE statements are used to set the current database or catalog, or change the resolution order and enabled status of module.

Run a USE statement

Java

USE statements can be executed with the executeSql() method of the TableEnvironment. The executeSql() method returns ‘OK’ for a successful USE operation, otherwise will throw an exception.

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

Scala

USE statements can be executed with the executeSql() method of the TableEnvironment. The executeSql() method returns ‘OK’ for a successful USE operation, otherwise will throw an exception.

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

Python

USE statements can be executed with the execute_sql() method of the TableEnvironment. The execute_sql() method returns ‘OK’ for a successful USE operation, otherwise will throw an exception.

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

SQL CLI

USE statements can be executed in SQL CLI.

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

Java

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
StreamTableEnvironment tEnv = StreamTableEnvironment.create(env);
// create a catalog
tEnv.executeSql("CREATE CATALOG cat1 WITH (...)");
tEnv.executeSql("SHOW CATALOGS").print();
// +-----------------+
// |    catalog name |
// +-----------------+
// | default_catalog |
// | cat1            |
// +-----------------+
// change default catalog
tEnv.executeSql("USE CATALOG cat1");
tEnv.executeSql("SHOW DATABASES").print();
// databases are empty
// +---------------+
// | database name |
// +---------------+
// +---------------+
// create a database
tEnv.executeSql("CREATE DATABASE db1 WITH (...)");
tEnv.executeSql("SHOW DATABASES").print();
// +---------------+
// | database name |
// +---------------+
// |        db1    |
// +---------------+
// change default database
tEnv.executeSql("USE db1");
// change module resolution order and enabled status
tEnv.executeSql("USE MODULES hive");
tEnv.executeSql("SHOW FULL MODULES").print();
// +-------------+-------+
// | module name |  used |
// +-------------+-------+
// |        hive |  true |
// |        core | false |
// +-------------+-------+

Scala

val env = StreamExecutionEnvironment.getExecutionEnvironment()
val tEnv = StreamTableEnvironment.create(env)
// create a catalog
tEnv.executeSql("CREATE CATALOG cat1 WITH (...)")
tEnv.executeSql("SHOW CATALOGS").print()
// +-----------------+
// |    catalog name |
// +-----------------+
// | default_catalog |
// | cat1            |
// +-----------------+
// change default catalog
tEnv.executeSql("USE CATALOG cat1")
tEnv.executeSql("SHOW DATABASES").print()
// databases are empty
// +---------------+
// | database name |
// +---------------+
// +---------------+
// create a database
tEnv.executeSql("CREATE DATABASE db1 WITH (...)")
tEnv.executeSql("SHOW DATABASES").print()
// +---------------+
// | database name |
// +---------------+
// |        db1    |
// +---------------+
// change default database
tEnv.executeSql("USE db1")
// change module resolution order and enabled status
tEnv.executeSql("USE MODULES hive")
tEnv.executeSql("SHOW FULL MODULES").print()
// +-------------+-------+
// | module name |  used |
// +-------------+-------+
// |        hive |  true |
// |        core | false |
// +-------------+-------+

Python

table_env = StreamTableEnvironment.create(...)
# create a catalog
table_env.execute_sql("CREATE CATALOG cat1 WITH (...)")
table_env.execute_sql("SHOW CATALOGS").print()
# +-----------------+
# |    catalog name |
# +-----------------+
# | default_catalog |
# | cat1            |
# +-----------------+
# change default catalog
table_env.execute_sql("USE CATALOG cat1")
table_env.execute_sql("SHOW DATABASES").print()
# databases are empty
# +---------------+
# | database name |
# +---------------+
# +---------------+
# create a database
table_env.execute_sql("CREATE DATABASE db1 WITH (...)")
table_env.execute_sql("SHOW DATABASES").print()
# +---------------+
# | database name |
# +---------------+
# |           db1 |
# +---------------+
# change default database
table_env.execute_sql("USE db1")
# change module resolution order and enabled status
table_env.execute_sql("USE MODULES hive")
table_env.execute_sql("SHOW FULL MODULES").print()
# +-------------+-------+
# | module name |  used |
# +-------------+-------+
# |        hive |  true |
# |        core | false |
# +-------------+-------+

SQL CLI

Flink SQL> CREATE CATALOG cat1 WITH (...);
[INFO] Catalog has been created.
Flink SQL> SHOW CATALOGS;
default_catalog
cat1
Flink SQL> USE CATALOG cat1;
Flink SQL> SHOW DATABASES;
Flink SQL> CREATE DATABASE db1 WITH (...);
[INFO] Database has been created.
Flink SQL> SHOW DATABASES;
db1
Flink SQL> USE db1;
Flink SQL> USE MODULES hive;
[INFO] Use modules succeeded!
Flink SQL> SHOW FULL MODULES;
+-------------+-------+
| module name |  used |
+-------------+-------+
|        hive |  true |
|        core | false |
+-------------+-------+
2 rows in set

USE CATALOG

USE CATALOG catalog_name

Set the current catalog. All subsequent commands that do not explicitly specify a catalog will use this one. If the provided catalog does not exist, an exception is thrown. The default current catalog is default_catalog.

USE MODULES

USE MODULES module_name1[, module_name2, ...]

Set the enabled modules with declared order. All subsequent commands will resolve metadata(functions/user-defined types/rules, etc.) within enabled modules and follow resolution order. A module is used by default when it is loaded. Loaded modules will become disabled if not used by USE MODULES statement. The default loaded and enabled module is core.

USE

USE [catalog_name.]database_name

Set the current database. All subsequent commands that do not explicitly specify a database will use this one. If the provided database does not exist, an exception is thrown. The default current database is default_database.