Database Reference
In-Depth Information
Check the table contents as follows:
warehouse_db=# SELECT * FROM tab_perl;
emp_id | emp_name | emp_city
--------+----------+----------
1 | Adam | Chicago
2 | John | Miami
3 | Roger | Boston
(3 rows)
This time the operation was successful and the table is updated.
Creating triggers in PL/Tcl
We will reuse the previous example to write trigger procedures in PL/Tcl. Let's go
through the syntax for some of the trigger variables and give some information:
$TG_name : This is the name of the trigger
$TG_table_name : This is the name of the table to which the trigger is
associated
$TG_op : This is a string that can have the value INSERT , UPDATE , DELETE ,
or TRUNCATE
$NEW : This is indexed by the column name; it's an associative array that
contains new row values for INSERT , UPDATE , or empty in the case of DELETE
$OLD : This is indexed by the column name; it's an associative array that
contains old row values for UPDATE or DELETE or empty in the case of INSERT
Let's start with creating a table that contains a few rows in the following manner:
warehouse_db=# CREATE TABLE tab_tcl
(
emp_id INT NOT NULL,
emp_name VARCHAR(10),
emp_city VARCHAR(10)
);
Insert rows in the tab_tcl table using the following statement:
warehouse_db=# INSERT INTO tab_tcl VALUES (1, 'Adam', 'Chicago');
warehouse_db=# INSERT INTO tab_tcl VALUES (2, 'John', 'Miami');
 
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