Trigger


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30  
31  
32  package org.hsqldb;
33  
34  // fredt@users 20030727 - signature altered to support update triggers
35  /*
36  
37  Contents of row1[] and row2[] in each type of trigger.
38  
39  BEFORE INSERT
40   - row1[] contains single String object = "Statement-level".
41  
42  AFTER INSERT
43   - row1[] contains single String object = "Statement-level".
44  
45  BEFORE UPDATE
46   - row1[] contains single String object = "Statement-level".
47  
48  AFTER UPDATE
49   - row1[] contains single String object = "Statement-level".
50  
51  BEFORE DELETE
52   - row1[] contains single String object = "Statement-level".
53  
54  AFTER DELETE
55   - row1[] contains single String object = "Statement-level".
56  
57  BEFORE INSERT FOR EACH ROW
58   - row2[] contains data about to be inserted and this can
59  be modified within the trigger such that modified data gets written to the
60  database.
61  
62  AFTER INSERT FOR EACH ROW
63   - row2[] contains data just inserted into the table.
64  
65  BEFORE UPDATE FOR EACH ROW
66   - row1[] contains currently stored data and not the data that is about to be
67  updated.
68  
69   - row2[] contains the data that is about to be updated.
70  
71  AFTER UPDATE FOR EACH ROW
72   - row1[] contains old stored data.
73   - row2[] contains the new data.
74  
75  BEFORE DELETE FOR EACH ROW
76   - row1[] contains row data about to be deleted.
77  
78  AFTER DELETE FOR EACH ROW
79   - row1[] contains row data that has been deleted.
80  
81  List compiled by Andrew Knight (quozzbat@users)
82  */
83  
84  /**
85   * The interface an HSQLDB TRIGGER must implement. The user-supplied class that
86   * implements this must have a default constructor.
87   *
88   * @author Peter Hudson
89   * @version 1.7.2
90   * @since 1.7.0
91   */
92  public interface Trigger {
93  
94      // indexes into the triggers list
95      int INSERT_AFTER      = 0;
96      int DELETE_AFTER      = 1;
97      int UPDATE_AFTER      = 2;
98      int INSERT_BEFORE     = INSERT_AFTER + TriggerDef.NUM_TRIGGER_OPS;
99      int DELETE_BEFORE     = DELETE_AFTER + TriggerDef.NUM_TRIGGER_OPS;
100     int UPDATE_BEFORE     = UPDATE_AFTER + TriggerDef.NUM_TRIGGER_OPS;
101     int INSERT_AFTER_ROW  = INSERT_AFTER + 2 * TriggerDef.NUM_TRIGGER_OPS;
102     int DELETE_AFTER_ROW  = DELETE_AFTER + 2 * TriggerDef.NUM_TRIGGER_OPS;
103     int UPDATE_AFTER_ROW  = UPDATE_AFTER + 2 * TriggerDef.NUM_TRIGGER_OPS;
104     int INSERT_BEFORE_ROW = INSERT_BEFORE + 2 * TriggerDef.NUM_TRIGGER_OPS;
105     int DELETE_BEFORE_ROW = DELETE_BEFORE + 2 * TriggerDef.NUM_TRIGGER_OPS;
106     int UPDATE_BEFORE_ROW = UPDATE_BEFORE + 2 * TriggerDef.NUM_TRIGGER_OPS;
107 
108     /**
109      * The method invoked upon each triggered action. <p>
110      *
111      * When UPDATE triggers are fired, oldRow contains the
112      * existing values of the table row and newRow contains the
113      * new values.<p>
114      *
115      * For INSERT triggers, oldRow is null and newRow contains the
116      * table row to be inserted.
117      *
118      * For DELETE triggers, newRow is null and oldRow contains the
119      * table row to be deleted.
120      *
121      * type contains the integer index id for trigger type, e.g.
122      * TriggerDef.INSERT_AFTER (fredt@users)
123      *
124      * @param trigName the name of the trigger
125      * @param tabName the name of the table upon which the
126      *      triggered action is occuring
127      * @param oldRow the old row
128      * @param newRow the new row
129      */
130     void fire(int type, String   trigName, String   tabName, Object  [] oldRow,
131               Object  [] newRow);
132 }
133
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