To Generate A Composite Key On A Table

Oct 08, 2017  Open the design view of the table and choose the columns that you want to add composite primary key, right click and select Set Primary Key option. Then the primary key will be created on that column. You can see the key against that column as shown in the figure. Now let us discuss how to create or add composite primary key using tsql. To create a composite primary key on two or more columns (fields), in table design view hold down the Ctrl key and left click on each of the columns, being sure to click on the 'field selector' (the small square to the left of the column name). Then right click and select 'Primary Key' from the shortcut menu. Question: To Generate A Composite Key On A Table In MySQL You Would: Use The AUTO-INCREMENT COMPOSITE Constraint Use The AUTOGENCOMPOSITE Constraint Create A Surrogate Key Create A Primary Key On Multiple Columns. A composite key is a combination of two or more columns in a table that can be used to uniquely identify each row in the table when the columns are combined uniqueness is guaranteed, but when it taken individually it does not guarantee uniqueness. Sometimes more than one attributes are needed to uniquely identify an entity. Creating a primary key in an existing table requires ALTER permission on the table. Using SQL Server Management Studio To create a primary key. In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design. In Table Designer, click the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you click the row selectors for the other columns. Add or change a table’s primary key in Access. To select more than one field to create a composite key, hold down CTRL and then click the row selector for each field. On the Design tab, in the Tools group, click Primary Key. A key indicator is added to the left of the field or fields that you specify as the primary key. In this article, we will learn about composite primary keys and how to create them in SQL Server. Composite primary key. Primary keys are special types of constraint that uniquely identify all rows in a table. Usually, we choose a single column as the primary key in our table to maintain data integrity.

  1. To Generate A Composite Key On A Table Crossword
  2. To Generate A Composite Key On A Table Video
  3. Example Of Composite Key
  4. Foreign Key

When creating a composite partitioned table, you use the PARTITION and SUBPARTITION clauses of the CREATE TABLE SQL statement.

To create a composite partitioned table, you start by using the PARTITIONBY {HASHRANGE [INTERVAL] LIST} clause of a CREATE TABLE statement. Next, you specify a SUBPARTITION BY clause that follows similar syntax and rules as the PARTITION BY clause.

The following topics are discussed:

4.2.1 Creating Composite Hash-* Partitioned Tables

Composite hash-* partitioning enables hash partitioning along two dimensions.

The composite hash-hash partitioning strategy has the most business value of the composite hash-* partitioned tables. This technique is beneficial to enable partition-wise joins along two dimensions.

In the following example, the number of subpartitions is specified when creating a composite hash-hash partitioned table; however, names are not specified. System generated names are assigned to partitions and subpartitions, which are stored in the default tablespace of the table.

Live SQL:

View and run a related example on Oracle Live SQL at Oracle Live SQL: Creating a Composite Hash-Hash Partition Table.

Example 4-17 Creating a composite hash-hash partitioned table

See Also:

Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

4.2.2 Creating Composite Interval-* Partitioned Tables

The concepts of interval-* composite partitioning are similar to the concepts for range-* partitioning.

However, you extend the PARTITION BY RANGE clause to include the INTERVAL definition. You must specify at least one range partition using the PARTITION clause. The range partitioning key value determines the high value of the range partitions, which is called the transition point, and the database automatically creates interval partitions for data beyond that transition point.

The subpartitions for intervals in an interval-* partitioned table are created when the database creates the interval. You can specify the definition of future subpartitions only with a subpartition template.

The following topics show examples for the different interval-* composite partitioning methods.

See Also:

Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

4.2.2.1 Creating Composite Interval-Hash Partitioned Tables

You can create an interval-hash partitioned table with multiple hash partitions by specifying multiple hash partitions in the PARTITION clause or by using a subpartition template.

If you do not use either of these methods, then future interval partitions get only a single hash subpartition.

The following example shows the sales table, interval partitioned using monthly intervals on time_id, with hash subpartitions by cust_id. This example specifies multiple hash partitions, without any specific tablespace assignment to the individual hash partitions.

Live SQL:

View and run a related example on Oracle Live SQL at Oracle Live SQL: Creating a Composite Interval-Hash Partitioned Table.

This next example shows the same sales table, interval partitioned using monthly intervals on time_id, again with hash subpartitions by cust_id. This time, however, individual hash partitions are stored in separate tablespaces. The subpartition template is used to define the tablespace assignment for future hash subpartitions.

4.2.2.2 Creating Composite Interval-List Partitioned Tables

To define list subpartitions for future interval-list partitions, you must use the subpartition template.

If you do not use the subpartitioning template, then the only subpartition that are created for every interval partition is a DEFAULT subpartition.

Example 4-18 shows the sales table, interval partitioned using daily intervals on time_id, with list subpartitions by channel_id.

Example 4-18 Creating a composite interval-list partitioned table

4.2.2.3 Creating Composite Interval-Range Partitioned Tables

To define range subpartitions for future interval-range partitions, you must use the subpartition template.

If you do not use the subpartition template, then the only subpartition that is created for every interval partition is a range subpartition with the MAXVALUE upper boundary.

Example 4-19 shows the sales table, interval partitioned using daily intervals on time_id, with range subpartitions by amount_sold.

Example 4-19 Creating a composite interval-range partitioned table

4.2.3 Creating Composite List-* Partitioned Tables

The concepts of list-hash, list-list, and list-range composite partitioning are similar to the concepts for range-hash, range-list, and range-range partitioning.

However, for list-* composite partitioning you specify PARTITION BY LIST to define the partitioning strategy.

The list partitions of a list-* composite partitioned table are similar to non-composite range partitioned tables. This organization enables optional subclauses of a PARTITION clause to specify physical and other attributes, including tablespace, specific to a partition segment. If not overridden at the partition level, then partitions inherit the attributes of their underlying table.

The subpartition descriptions, in the SUBPARTITION or SUBPARTITIONS clauses, are similar to range-* composite partitioning methods.

The following topics show examples for the different list-* composite partitioning methods.

See Also:

  • Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

  • About Creating Composite Range-Hash Partitioned Tables for more information about the subpartition definition of a list-hash composite partitioning method

  • About Creating Composite Range-List Partitioned Tables for more information about the subpartition definition of a list-list composite partitioning method

  • Creating Composite Range-Range Partitioned Tables for more information about the subpartition definition of a list-range composite partitioning method

4.2.3.1 Creating Composite List-Hash Partitioned Tables

The example in this topic shows how to create a composite list-hash partitioned table.

Example 4-20 shows an accounts table that is list partitioned by region and subpartitioned using hash by customer identifier.

Example 4-20 Creating a composite list-hash partitioned table

4.2.3.2 Creating Composite List-List Partitioned Tables

The example in this topic shows how to create a composite list-list partitioned table.

Example 4-21 shows an accounts table that is list partitioned by region and subpartitioned using list by account status.

Live SQL:

View and run a related example on Oracle Live SQL at Oracle Live SQL: Creating a Composite List-List Partitioned Table.

Example 4-21 Creating a composite list-list partitioned table

4.2.3.3 Creating Composite List-Range Partitioned Tables

The example in this topic shows how to create a composite list-range partitioned table.

Example 4-22 shows an accounts table that is list partitioned by region and subpartitioned using range by account balance, and row movement is enabled. Subpartitions for different list partitions could have different ranges specified.

Example 4-22 Creating a composite list-range partitioned table

4.2.4 Creating Composite Range-* Partitioned Tables

The methods for creating composite range-* partitioned tables are introduced in this topic.

The following topics show examples of the different range-* composite partitioning methods.

See Also:

Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

Generate

4.2.4.1 About Creating Composite Range-Hash Partitioned Tables

The partitions of a range-hash partitioned table are logical structures only, because their data is stored in the segments of their subpartitions.

As with partitions, these subpartitions share the same logical attributes. Unlike range partitions in a range-partitioned table, the subpartitions cannot have different physical attributes from the owning partition, although they are not required to reside in the same tablespace.

The following topics are discussed:

See Also:

Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

4.2.4.1.1 Creating a Composite Range-Hash Partitioned Table With the Same Tablespaces

The example in this topic shows how to create a composite range-hash partitioned table using the same tablespaces.

The statement in Example 4-23 creates a range-hash partitioned table. Four range partitions are created, each containing eight subpartitions. Because the subpartitions are not named, system generated names are assigned, but the STORE IN clause distributes them across the 4 specified tablespaces (ts1, ts2, ts3,ts4).

Example 4-23 Creating a composite range-hash partitioned table using one STORE IN clause

4.2.4.1.2 Creating a Composite Range-Hash Partitioned Table With Varying Tablespaces

The example in this topic shows how to create a composite range-hash partitioned table using varying tablespaces.

Attributes specified for a range partition apply to all subpartitions of that partition. You can specify different attributes for each range partition, and you can specify a STORE IN clause at the partition level if the list of tablespaces across which the subpartitions of that partition should be spread is different from those of other partitions. This is illustrated in the following example.

4.2.4.1.3 Creating a Local Index Across Multiple Tablespaces

The example in this topic shows how to create a local index across multiple tablespaces.

The following statement is an example of creating a local index on a table where the index segments are spread across tablespaces ts7, ts8, and ts9.

This local index is equipartitioned with the base table so that it consists of as many partitions as the base table. Each index partition consists of as many subpartitions as the corresponding base table partition. Index entries for rows in a given subpartition of the base table are stored in the corresponding subpartition of the index.

4.2.4.2 About Creating Composite Range-List Partitioned Tables

The range partitions of a range-list composite partitioned table are described as the same for non-composite range partitioned tables.

This organization enables optional subclauses of a PARTITION clause to specify physical and other attributes, including tablespace, specific to a partition segment. If not overridden at the partition level, partitions inherit the attributes of their underlying table.

The list subpartition descriptions, in the SUBPARTITION clauses, are described as for non-composite list partitions, except the only physical attribute that can be specified is a tablespace (optional). Subpartitions inherit all other physical attributes from the partition description.

The following topics are discussed:

See Also:

Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

4.2.4.2.1 Creating a Composite Range-List Partitioned Table

The example in this topic shows how to create a composite range-list partitioned table.

Example 4-24 illustrates how range-list partitioning might be used. The example tracks sales data of products by quarters and within each quarter, groups it by specified states.

A row is mapped to a partition by checking whether the value of the partitioning column for a row falls within a specific partition range. The row is then mapped to a subpartition within that partition by identifying the subpartition whose descriptor value list contains a value matching the subpartition column value. For example, the following list describes how some sample rows are inserted.

  • (10, 4532130, '23-Jan-1999', 8934.10, 'WA') maps to subpartition q1_1999_northwest

  • (20, 5671621, '15-May-1999', 49021.21, 'OR') maps to subpartition q2_1999_northwest

  • (30, 9977612, '07-Sep-1999', 30987.90, 'FL') maps to subpartition q3_1999_southeast

  • (40, 9977612, '29-Nov-1999', 67891.45, 'TX') maps to subpartition q4_1999_southcentral

  • (40, 4532130, '5-Jan-2000', 897231.55, 'TX') does not map to any partition in the table and displays an error

  • (50, 5671621, '17-Dec-1999', 76123.35, 'CA') does not map to any subpartition in the table and displays an error

Live SQL:

View and run a related example on Oracle Live SQL at Oracle Live SQL: Creating a Composite Range-List Partitioned Table.

Example 4-24 Creating a composite range-list partitioned table

4.2.4.2.2 Creating a Composite Range-List Partitioned Table Specifying Tablespaces

The example in this topic shows how to create a composite range-list partitioned table while specifying tablespaces.

The partitions of a range-list partitioned table are logical structures only, because their data is stored in the segments of their subpartitions. The list subpartitions have the same characteristics as list partitions. You can specify a default subpartition, just as you specify a default partition for list partitioning.

The following example creates a table that specifies a tablespace at the partition and subpartition levels. The number of subpartitions within each partition varies, and default subpartitions are specified. This example results in the following subpartition descriptions:

  • All subpartitions inherit their physical attributes, other than tablespace, from tablespace level defaults. This is because the only physical attribute that has been specified for partitions or subpartitions is tablespace. There are no table level physical attributes specified, thus tablespace level defaults are inherited at all levels.

  • The first 4 subpartitions of partition q1_1999 are all contained in tbs_1, except for the subpartition q1_others, which is stored in tbs_4 and contains all rows that do not map to any of the other partitions.

  • The 6 subpartitions of partition q2_1999 are all stored in tbs_2.

  • The first 2 subpartitions of partition q3_1999 are all contained in tbs_3, except for the subpartition q3_others, which is stored in tbs_4 and contains all rows that do not map to any of the other partitions.

  • There is no subpartition description for partition q4_1999. This results in one default subpartition being created and stored in tbs_4. The subpartition name is system generated in the form SYS_SUBPn.

4.2.4.3 Creating Composite Range-Range Partitioned Tables

The range partitions of a range-range composite partitioned table are similar to non-composite range partitioned tables.

This organization enables optional subclauses of a PARTITION clause to specify physical and other attributes, including tablespace, specific to a partition segment. If not overridden at the partition level, then partitions inherit the attributes of their underlying table.

The range subpartition descriptions, in the SUBPARTITION clauses, are similar to non-composite range partitions, except the only physical attribute that can be specified is an optional tablespace. Subpartitions inherit all other physical attributes from the partition description.

The following example illustrates how range-range partitioning might be used. The example tracks shipments. The service level agreement with the customer states that every order is delivered in the calendar month after the order was placed. The following types of orders are identified:

To Generate A Composite Key On A Table Crossword

A row is mapped to a partition by checking whether the value of the partitioning column for a row falls within a specific partition range. The row is then mapped to a subpartition within that partition by identifying whether the value of the subpartitioning column falls within a specific range. For example, a shipment with an order date in September 2006 and a delivery date of October 28, 2006 falls in partition p06_oct_a.

To Generate A Composite Key On A Table Video

  • E (EARLY): orders that are delivered before the middle of the next month after the order was placed. These orders likely exceed customers' expectations.

  • A (AGREED): orders that are delivered in the calendar month after the order was placed (but not early orders).

  • L (LATE): orders that were only delivered starting the second calendar month after the order was placed.

See Also:

Specifying Subpartition Templates to Describe Composite Partitioned Tables to learn how using a subpartition template can simplify the specification of a composite partitioned table

4.2.5 Specifying Subpartition Templates to Describe Composite Partitioned Tables

You can create subpartitions in a composite partitioned table using a subpartition template.

A subpartition template simplifies the specification of subpartitions by not requiring that a subpartition descriptor be specified for every partition in the table. Instead, you describe subpartitions only one time in a template, then apply that subpartition template to every partition in the table. For interval-* composite partitioned tables, the subpartition template is the only way to define subpartitions for interval partitions.

The subpartition template is used whenever a subpartition descriptor is not specified for a partition. If a subpartition descriptor is specified, then it is used instead of the subpartition template for that partition. If no subpartition template is specified, and no subpartition descriptor is supplied for a partition, then a single default subpartition is created.

The following topics are discussed:

4.2.5.1 Specifying a Subpartition Template for a *-Hash Partitioned Table

For range-hash, interval-hash, and list-hash partitioned tables, the subpartition template can describe the subpartitions in detail, or it can specify just the number of hash subpartitions.

Example 4-25 creates a range-hash partitioned table using a subpartition template and displays the subpartition names and tablespaces.

The example produces a table with the following description.

  • Every partition has four subpartitions as described in the subpartition template.

  • Each subpartition has a tablespace specified. It is required that if a tablespace is specified for one subpartition in a subpartition template, then one must be specified for all.

  • The names of the subpartitions, unless you use interval-* subpartitioning, are generated by concatenating the partition name with the subpartition name in the form:

    partition name_subpartition name

    For interval-* subpartitioning, the subpartition names are system-generated in the form:

    SYS_SUBPn

Example 4-25 Creating a range-hash partitioned table with a subpartition template

4.2.5.2 Specifying a Subpartition Template for a *-List Partitioned Table

For -list partitioned tables, the subpartition template can describe the subpartitions in detail.

Example 4-26, for a range-list partitioned table, illustrates how using a subpartition template can help you stripe data across tablespaces. In this example, a table is created where the table subpartitions are vertically striped, meaning that subpartition n from every partition is in the same tablespace.

If you specified the tablespaces at the partition level (for example, tbs_1 for partition q1_1999, tbs_2 for partition q2_1999, tbs_3 for partition q3_1999, and tbs_4 for partition q4_1999) and not in the subpartition template, then the table would be horizontally striped. All subpartitions would be in the tablespace of the owning partition.

Example 4-26 Creating a range-list partitioned table with a subpartition template

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APPLIES TO: SQL Server 2016 and later Azure SQL Database Azure Synapse Analytics (SQL DW) Parallel Data Warehouse

You can define a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index, or a nonclustered index if specified as such.

Before You Begin

Limitations and Restrictions

  • A table can contain only one PRIMARY KEY constraint.

  • All columns defined within a PRIMARY KEY constraint must be defined as NOT NULL. If nullability is not specified, all columns participating in a PRIMARY KEY constraint have their nullability set to NOT NULL.

Security

Permissions

Creating a new table with a primary key requires CREATE TABLE permission in the database and ALTER permission on the schema in which the table is being created.

Generate rsa key pair for ssh. Creating a primary key in an existing table requires ALTER permission on the table.

Using SQL Server Management Studio

To create a primary key

  1. In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design.
  2. In Table Designer, click the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you click the row selectors for the other columns.
  3. Right-click the row selector for the column and select Set Primary Key.

Caution

If you want to redefine the primary key, any relationships to the existing primary key must be deleted before the new primary key can be created. A message will warn you that existing relationships will be automatically deleted as part of this process.

A primary key column is identified by a primary key symbol in its row selector.

If a primary key consists of more than one column, duplicate values are allowed in one column, but each combination of values from all the columns in the primary key must be unique.

If you define a compound key, the order of columns in the primary key matches the order of columns as shown in the table. However, you can change the order of columns after the primary key is created. For more information, see Modify Primary Keys.

Using Transact-SQL

To create a primary key in an existing table

The following example creates a primary key on the column TransactionID in the AdventureWorks database.

To create a primary key in a new table

The following example creates a table and defines a primary key on the column TransactionID in the AdventureWorks database.

To create a primary key with clustered index in a new table

Example Of Composite Key

The following example creates a table and defines a primary key on the column CustomerID and a clustered index on TransactionID in the AdventureWorks database.

Foreign Key

See Also