NexusDB V3 Manual
System Functions
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NexusDB Manual V3 > SQL Reference > SQL Functions
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The following table shows the special system functions supported in NexusDB SQL.
Syntax
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Data type
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Notes
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USER
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VARCHAR
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Returns the user name associated with the current session.
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CURRENT_USER
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VARCHAR
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Equivalent to USER.
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SESSION_USER
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VARCHAR
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Equivalent to USER.
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SYSTEM_ROW#
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DWORD
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The function can only be defined as the first select column in query specifications, and will assign a sequential (zero-based) row-id to the rows in the result set. Cannot be used inside other functions.
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NEWGUID
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GUID
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Returns a generated GUID value.
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ROWSREAD
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Returns the number of rows in the result set of a SELECT statement executed prior to calling ROWSREAD.
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ROWSAFFECTED
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Returns the number of rows affected by a data-change statement executed prior to calling ROWSAFFECTED.
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ERROR_MESSAGE
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VARCHAR
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Returns the last error message from the system. The function can only be used in the CATCH clause of the TRY statement.
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Examples
1)
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The following example selects all appointments made by the current user:
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SELECT *
FROM orders
WHERE takenBy = CURRENT_USER
2)
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The following example retrieves a unique row-id and the customer name:
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SELECT SYSTEM_ROW# AS row_id, customer_name
FROM customers
3)
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The following example uses the NEWGUID function to assign a value to the documentID column:
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INSERT INTO documents ( documentID, title )
VALUES ( NEWGUID, 'NexusDB V3 features' )
4)
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The following example shows how ERROR_MESSAGE is used in the TRY statement:
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START TRANSACTION;
TRY
DROP TABLE garbage;
COMMIT;
CATCH POSITION( 'Unable to open table' IN ERROR_MESSAGE ) <> 0
ROLLBACK;
SIGNAL ERROR_MESSAGE;
END;
Conformance
SQL:2003 standard
NexusDB extensions
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Core SQL
SYSTEM_ROW#
NEWGUID
ROWSREAD
ROWSAFFECTED
ERROR_MESSAGE
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© Nexus Database Systems Pty Ltd.
