CREATE TABLE [USING]

Άρθρο
12/12/2024

Applies to: check marked yes Databricks SQL Databricks Runtime

Defines a managed or external table, optionally using a data source.

Syntax

{ { [CREATE OR] REPLACE TABLE | CREATE [EXTERNAL] TABLE [ IF NOT EXISTS ] }
  table_name
  [ table_specification ]
  [ USING data_source ]
  [ table_clauses ]
  [ AS query ] }

table_specification
  ( { column_identifier column_type [ column_properties ] } [, ...]
    [ , table_constraint ] [...] )

column_properties
  { NOT NULL |
    COLLATE collation_name |
    GENERATED ALWAYS AS ( expr ) |
    GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( [ START WITH start ] [ INCREMENT BY step ] ) ] |
    DEFAULT default_expression |
    COMMENT column_comment |
    column_constraint |
    MASK clause } [ ... ]

table_clauses
  { OPTIONS clause |
    PARTITIONED BY clause |
    CLUSTER BY clause |
    clustered_by_clause |
    LOCATION path [ WITH ( CREDENTIAL credential_name ) ] |
    COMMENT table_comment |
    TBLPROPERTIES clause |
    WITH { ROW FILTER clause } } [...]

clustered_by_clause
  { CLUSTERED BY ( cluster_column [, ...] )
    [ SORTED BY ( { sort_column [ ASC | DESC ] } [, ...] ) ]
    INTO num_buckets BUCKETS }

Parameters

REPLACE

If specified, replaces the table and its content if it already exists. This clause is only supported for Delta Lake tables.

REPLACE preserves the table history.

Note

Azure Databricks strongly recommends using REPLACE instead of dropping and re-creating Delta Lake tables.
EXTERNAL

If specified, creates an external table. When creating an external table you must also provide a LOCATION clause. When an external table is dropped the files at the LOCATION will not be dropped.
IF NOT EXISTS

If specified and a table with the same name already exists, the statement is ignored.

IF NOT EXISTS cannot coexist with REPLACE, which means CREATE OR REPLACE TABLE IF NOT EXISTS is not allowed.
table_name

The name of the table to be created. The name must not include a temporal specification or options specification. If the name is not qualified the table is created in the current schema.

Tables created in hive_metastore can only contain alphanumeric ASCII characters and underscores (INVALID_SCHEMA_OR_RELATION_NAME).
table_specification

This optional clause defines the list of columns, their types, properties, descriptions, and column constraints.

If you do not define columns the table schema you must specify either AS query or LOCATION.
- column_identifier
  
  A unique name for the column.
  
  Column identifiers of Delta Lake tables without column mapping property ('delta.columnMapping.mode' = 'name') must not contain spaces or the following characters: , ; { } ( ) \n \t = .
  
  Column identifiers of AVRO table must start with an underscore (_) or a Unicode letter (including non-ASCII letters) and be followed by a combination of Unicode letters, digits, and underscores.
- column_type
  
  Specifies the data type of the column. Not all data types supported by Azure Databricks are supported by all data sources.
- NOT NULL
  
  If specified the column will not accept NULL values. This clause is only supported for Delta Lake tables.
- COLLATE collation_name
  
  Applies to: Databricks Runtime 16.1 and above
  
  For STRING column_type optionally names the collation to apply for comparison and sort operations on this column. The default collation is UTF8_BINARY.
- GENERATED ALWAYS AS ( expr )
  
  When you specify this clause the value of this column is determined by the specified expr.
  
  expr may be composed of literals, column identifiers within the table, and deterministic, built-in SQL functions or operators except:
  - Aggregate functions
  - Analytic window functions
  - Ranking window functions
  - Table valued generator functions
  Also expr must not contain any subquery.
- GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( [ START WITH start ] [ INCREMENT BY step ] ) ]
  
  Applies to: Databricks SQL Databricks Runtime 10.4 LTS and above
  
  Defines an identity column. When you write to the table, and do not provide values for the identity column, it will be automatically assigned a unique and statistically increasing (or decreasing if step is negative) value. This clause is only supported for Delta Lake tables. This clause can only be used for columns with BIGINT data type.
  
  The automatically assigned values start with start and increment by step. Assigned values are unique but are not guaranteed to be contiguous. Both parameters are optional, and the default value is 1. step cannot be 0.
  
  If the automatically assigned values are beyond the range of the identity column type, the query will fail.
  
  When ALWAYS is used, you cannot provide your own values for the identity column.
  
  The following operations are not supported:
  - PARTITIONED BY an identity column
  - UPDATE an identity column
  Note
  
  Declaring an identity column on a Delta table disables concurrent transactions. Only use identity columns in use cases where concurrent writes to the target table are not required.
- DEFAULT default_expression
  
  Applies to: Databricks SQL Databricks Runtime 11.3 LTS and above
  
  Defines a DEFAULT value for the column which is used on INSERT, UPDATE, and MERGE ... INSERT when the column is not specified.
  
  If no default is specified DEFAULT NULL is applied for nullable columns.
  
  default_expression may be composed of literals, and built-in SQL functions or operators except:
  - Aggregate functions
  - Analytic window functions
  - Ranking window functions
  - Table valued generator functions
  Also default_expression must not contain any subquery.
  
  DEFAULT is supported for CSV, JSON, PARQUET, and ORC sources.
- COMMENT column_comment
  
  A string literal to describe the column.
- column_constraint
  
  Adds a primary key or foreign key constraint to the column in a Delta Lake table.
  
  Constraints are not supported for tables in the hive_metastore catalog.
  
  To add a check constraint to a Delta Lake table use ALTER TABLE.
- MASK clause
  
  Applies to: Databricks SQL Databricks Runtime 12.2 LTS and above Unity Catalog only
  
  Important
  
  This feature is in Public Preview.
  
  Adds a column mask function to anonymize sensitive data. All subsequent queries from that column receive the result of evaluating that function over the column in place of the column’s original value. This can be useful for fine-grained access control purposes where the function can inspect the identity or group memberships of the invoking user to decide whether to redact the value.
- table_constraint
  
  Adds an informational primary key or informational foreign key constraints to the Delta Lake table.
  
  Key constraints are not supported for tables in the hive_metastore catalog.
  
  To add a check constraint to a Delta Lake table use ALTER TABLE.
USING data_source

data_source can be either a file-format or a federated JDBC data source.

The file-format must be one of the following:
- AVRO
- BINARYFILE
- CSV
- DELTA
- JSON
- ORC
- PARQUET
- TEXT
For any file-format other than DELTA you must also specify a LOCATION unless the table catalog is hive_metastore.

The following federated JDBC sources are supported:
- POSTGRESQL
- SQLSERVER
- MYSQL
- BIGQUERY
- NETSUITE
- ORACLE
- REDSHIFT
- SNOWFLAKE
- SQLDW
- SYNAPSE
- SALESFORCE
- SALESFORCE_DATA_CLOUD
- TERADATA
- WORKDAY_RAAS
- MONGODB
When specifying a federated JDBC source, you must also specify the OPTIONS clause with the necessary connection information. See Query databases using JDBC for more information on querying federated data sources.

The following additional file formats to use for the table are supported in Databricks Runtime:
- JDBC
- LIBSVM
- a fully-qualified class name of a custom implementation of org.apache.spark.sql.sources.DataSourceRegister.
If USING is omitted, the default is DELTA.

The following applies to: Databricks Runtime

HIVE is supported to create a Hive SerDe table in Databricks Runtime. You can specify the Hive-specific file_format and row_format using the OPTIONS clause, which is a case-insensitive string map. The option_keys are:
- FILEFORMAT
- INPUTFORMAT
- OUTPUTFORMAT
- SERDE
- FIELDDELIM
- ESCAPEDELIM
- MAPKEYDELIM
- LINEDELIM
table_clauses

Optionally specify location, partitioning, clustering, options, comments, and user defined properties for the new table. Each sub clause may only be specified once.
- PARTITIONED BY
  
  An optional clause to partition the table by a subset of columns.
  
  Note
  
  If you don’t define a Delta table, partitioning columns are placed at the end of the table, even if they are defined earlier in the column specification. Consider using CLUSTER BY instead of PARTITIONED BY for Delta tables.
- CLUSTER BY
  
  Applies to: Databricks SQL Databricks Runtime 13.3 and later
  
  An optional clause to cluster a Delta table by a subset of columns. To cluster other tables use clustered_by_clause.
  
  Delta Lake liquid clustering cannot be combined with PARTITIONED BY.
- clustered_by_clause
  
  Optionally cluster the table or each partition into a fixed number of hash buckets using a subset of the columns.
  
  Clustering is not supported for Delta Lake tables.
  - CLUSTERED BY
    
    Specifies the set of columns by which to cluster each partition, or the table if no partitioning is specified.
    - cluster_column
      
      An identifier referencing a column_identifier in the table. If you specify more than one column there must be no duplicates. Since a clustering operates on the partition level you must not name a partition column also as a cluster column.
  - SORTED BY
    
    Optionally maintains a sort order for rows in a bucket.
    - sort_column
      
      A column to sort the bucket by. The column must not be partition column. Sort columns must be unique.
    - ASC or DESC
      
      Optionally specifies whether sort_column is sorted in ascending (ASC) or descending (DESC) order. The default values is ASC.
  - INTO num_buckets BUCKETS
    
    An INTEGER literal specifying the number of buckets into which each partition (or the table if no partitioning is specified) is divided.
- LOCATION path [ WITH ( CREDENTIAL credential_name ) ]
  
  An optional path to the directory where table data is stored, which could be a path on distributed storage. path must be a STRING literal. If you specify no location the table is considered a managed table and Azure Databricks creates a default table location.
  
  Specifying a location makes the table an external table.
  
  For tables that do not reside in the hive_metastore catalog, the table path must be protected by an external location unless a valid storage credential is specified.
  
  You cannot create external tables in locations that overlap with the location of managed tables.
  
  For a Delta Lake table the table configuration is inherited from the LOCATION if data is present. Therefore, if any TBLPROPERTIES, table_specification, or PARTITIONED BY clauses are specified for Delta Lake tables they must exactly match the Delta Lake location data.
- OPTIONS
  
  Sets or resets one or more user defined table options.
- COMMENT table_comment
  
  A string literal to describe the table.
- TBLPROPERTIES
  
  Optionally sets one or more user defined properties.
- WITH ROW FILTER clause
  
  Applies to: Databricks SQL Databricks Runtime 12.2 LTS and above Unity Catalog only
  
  Adds a row filter function to the table. All subsequent queries from that table will receive a subset of the rows where the function evaluates to boolean TRUE. This can be useful for fine-grained access control purposes where the function can inspect the identity or group memberships of the invoking user to decide whether to filter certain rows.
AS query

This optional clause populates the table using the data from query. When you specify a query you must not also specify a table_specification. The table schema is derived from the query.

Note that Azure Databricks overwrites the underlying data source with the data of the input query, to make sure the table gets created contains exactly the same data as the input query.

Examples

-- Creates a Delta table
> CREATE TABLE student (id INT, name STRING, age INT);

-- Use data from another table
> CREATE TABLE student_copy AS SELECT * FROM student;

-- Creates a CSV table from an external directory
> CREATE TABLE student USING CSV LOCATION '/path/to/csv_files';

-- Specify table comment and properties
> CREATE TABLE student (id INT, name STRING, age INT)
    COMMENT 'this is a comment'
    TBLPROPERTIES ('foo'='bar');

-- Specify table comment and properties with different clauses order
> CREATE TABLE student (id INT, name STRING, age INT)
    TBLPROPERTIES ('foo'='bar')
    COMMENT 'this is a comment';

-- Create partitioned table
> CREATE TABLE student (id INT, name STRING, age INT)
    PARTITIONED BY (age);

-- Create a table with a generated column
> CREATE TABLE rectangles(a INT, b INT,
                          area INT GENERATED ALWAYS AS (a * b));

-- Create a table with a string column with a case-insensitive collation.
> CREATE TABLE names(name STRING COLLATE UNICODE_CI);

-- Create an external table connected to Oracle
> CREATE TABLE IF NOT EXISTS ora_tab
  USING ORACLE
  OPTIONS (
    url '<jdbc-url>',
    dbtable '<table-name>',
    user '<username>',
    password '<password>'
);

> SELECT * FROM ora_tab;

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CREATE TABLE [USING]

Syntax

Parameters

Examples

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Κοινή χρήση μέσω

CREATE TABLE [USING]

Syntax

Parameters

Examples

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