Programming Q Parameters | Accessing tables with SQL commands
10
HEIDENHAIN | TNC 620 | Conversational Programming User's Manual | 10/2017
437
SQL ROLLBACK
Example
11 SQL BIND Q881 "Tab_Example.Meas_No"
12 SQL BIND Q882 "Tab_Example.Meas_X"
13 SQL BIND Q883 "Tab_Example.Meas_Y"
14 SQL BIND Q884 "Tab_Example.Meas_Z"
. . .
20 SQL Q5 "SELECT Meas_no,Meas_X,Meas_Y, Meas_Z FROM
Tab_Example"
. . .
30 SQL FETCH Q1 HANDLE Q5 INDEX+Q2
. . .
50 SQL ROLLBACK Q1 HANDLE Q5
SQL ROLLBACK discards all of the changes and additions of a
transaction. The transaction is defined via the HANDLE to be
specified.
The function of the SQL command SQL ROLLBACK depends on the
INDEX:
Without INDEX:
All changes and additions to the transaction are discarded
A lock that was set with SELECT...FOR UPDATE is canceled.
The transaction is concluded (the HANDLE loses its validity)
With INDEX:
Only the indexed row remains in the result set (all other
rows are removed)
Any changes and additions made in the rows that are not
specified are discarded
A lock that has been set with SELECT...FOR UPDATE
remains only for indexed row (all other locks are canceled)
The specified (indexed) row becomes the new row 0 of the
result-set
The transaction is not concluded (the HANDLE keeps its
validity)
It is necessary to later concluded the transaction using SQL
ROLLBACK or SQL COMMIT
Parameter No. for result (return value for the
control):
0 successful transaction
1 successful transaction
Database: SQL access ID: Define Q parameters
for the HANDLE (for identifying the transaction)
Database: Index to SQL result: Row that
remains in the result set
Program the row number directly
Program the Q parameter containing the
index
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