When adding a UNIQUE index on a column (or a set of columns) which have duplicated values, an error will be produced and the statement will be stopped.
This is also true for non-transactional tables. If another connection is using the table, a metadata lock is active, and this statement will wait until the lock is released. You can also change the comment for the table and the storage engine of the | EXCHANGE PARTITION partition_name WITH TABLE tbl_nameĪLTER TABLE enables you to change the structure of an existing table.įor example, you can add or delete columns, create or destroy indexes,Ĭhange the type of existing columns, or rename columns or the table | partition_options | CONVERT TABLE normal_table TO partition_definition | CONVERT PARTITION partition_name TO TABLE tbl_name RENAME table > DESCRIBE student col_name data_type comment - name string NULL rollno int NULL age int NULL # Partition Information # col_name data_type comment age int NULL > ALTER TABLE Student RENAME TO StudentInfo - After Renaming the table > DESCRIBE StudentInfo col_name data_type comment - name string NULL rollno int NULL age int NULL # Partition Information # col_name data_type comment age int NULL - RENAME partition > SHOW PARTITIONS StudentInfo partition - age = 10 age = 11 age = 12 > ALTER TABLE default. Not all data types supported by Databricks are supported by all data sources. Specifies the data type of the column or field. When you set a default using ALTER COLUMN, existing rows are not affected by that change. If the default includes a non-deterministic function such as rand or current_timestamp the value is computed once when the ALTER TABLE is executed,Īnd applied as a constant to pre-existing rows.įor newly inserted rows, the default expression runs once per rows.
When you define the default for a newly added column, the default applies to all pre-existing rows. If no default is specified DEFAULT NULL is implied for nullable columns.ĭefault_expression may be composed of literals, built-in SQL functions, or operators except:ĭefault_expression must not contain a subquery.ĭEFAULT is supported for CSV, JSON, ORC, and PARQUET sources. For columns defined with NOT NULL you need to provide a value on every future INSERT operationĭefines a DEFAULT value for the column which is used on INSERT and MERGE. For nullable columns this is equivalent to SET DEFAULT NULL. Removes the default expression from the column. This option is only supported for identity columns on Delta Lake tables.Īpplies to: Databricks SQL SQL warehouse version 2022.35 or higher Databricks Runtime 11.2 and above After this command, the next automatically assigned identity value will start from start + (n + 1) * step, where n is the smallest value that satisfies start + n * step >= max() (for a positive step).
This option evaluates the state and updates the metadata to be consistent with the actual data. When you write your own values to an identity column, it might not comply with the metadata. Synchronize the metadata of an identity column with the actual data. This option is only supported for Delta Lake tables.ĭelta Lake will ensure the constraint is valid for all existing and new data.Īpplies to: Databricks SQL Databricks Runtime 10.3 and above This clause is only supported if table_name is a Delta table.Ĭhanges the domain of valid column values to exclude nulls SET NOT NULL, or include nulls DROP NOT NULL. Moves the column from its current position to the front ( FIRST) or immediately AFTER the identifier. The fully qualified name of the field to be altered.Īll components of the path to the nested field must exist.Ĭhanges the description of the column_name column. INSERT OVERWRITE DIRECTORY with Hive format.Privileges and securable objects in the Hive metastore.Privileges and securable objects in Unity Catalog.
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