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SQLTableExportedKeys[conn,table]

returns information about foreign keys that reference the primary key of table.

Details and Options
Details and Options Details and Options
Examples  
Basic Examples  
See Also
Tech Notes
Related Guides
DatabaseLink`
DatabaseLink`

SQLTableExportedKeys

SQLTableExportedKeys[conn,table]

returns information about foreign keys that reference the primary key of table.

Details and Options

  • To use SQLTableExportedKeys, you first need to load DatabaseLink using Needs["DatabaseLink`"].
  • The following options can be given:
  • "Catalog"Nonedatabase catalog to use
    "Schema"Nonedatabase schema to use
    "ShowColumnHeadings"Falsewhether to return headings with the results

Examples

Basic Examples  (1)

Wolfram Language code: Needs["DatabaseLink`"]

If you find that the examples in this section do not work as shown, you may need to install or restore the example database with the DatabaseLink`DatabaseExamples` package, as described in Using the Example Databases.

Open a connection:

Wolfram Language code: conn = OpenSQLConnection["demo"];

Create a table with a primary key:

Wolfram Language code: SQLCreateTable[conn, SQLTable["PEOPLE"], {SQLColumn["id", "DataTypeName" -> "Integer", "PrimaryKey" -> True], SQLColumn["Name", "DataTypeName" -> "VARCHAR", "DataLength" -> 255], SQLColumn["Age", "DataTypeName" -> "Integer"] }]

Create another table. The "\"\!\(\*StyleBox[\"PersonId\", \"InlineCode\"]\)\!\(\*StyleBox[\"\\\"\", \"InlineCode\"]\)" column will be used for a foreign key constraint referencing the "PEOPLE" table's primary key:

Wolfram Language code: SQLCreateTable[conn, SQLTable["EMPLOYEES"], {SQLColumn["id", "DataTypeName" -> "Integer", "PrimaryKey" -> True], SQLColumn["PersonId", "DataTypeName" -> "Integer"], SQLColumn["Department", "DataTypeName" -> "VARCHAR", "DataLength" -> 255], SQLColumn["Tenure", "DataTypeName" -> "Integer"] }]

Add the foreign key constraint:

Wolfram Language code: SQLExecute[conn, "ALTER TABLE EMPLOYEES ADD CONSTRAINT FK_PersonId FOREIGN KEY (PersonId) REFERENCES PEOPLE(id)"]

The foreign key appears as an index in the "EMPLOYEES" table:

Wolfram Language code: SQLTableIndexInformation[conn, "EMPLOYEES", "ShowColumnHeadings" -> True]//TableForm

The primary key column in the "PEOPLE" table now appears as an exported key:

Wolfram Language code: SQLTableExportedKeys[conn, "PEOPLE", "ShowColumnHeadings" -> True]//TableForm
Wolfram Language code: SQLDropTable[conn, "EMPLOYEES"]
Wolfram Language code: SQLDropTable[conn, "PEOPLE"]
Wolfram Language code: CloseSQLConnection[conn];